Health and Safety Executive

Analysis of ERRV trials data from ERRVA and Seacroft

Prepared by Serco Assurance for the Health and Safety Executive 2007

RR569 Research Report

Health and Safety Executive

Analysis of ERRV trials data from ERRVA and Seacroft

JK Robson Building 150 Harwell International Business Centre Didcot Oxfordshire OX11 0RA

For a number of years data have been collected by several parties recording the frequency, circumstances and prevailing conditions when ERRVs on the UKCS carried out trials with their rescue craft. Some data have been collected as part of independently witnessed validation trials whereas others, gathered as part of an industry initiative to improve standards, was recorded by the vessels' crew. In themselves the benefit of the individual records is somewhat limited but when combined with the results of other trials carried out in the same UKCS area it is possible to define trends and similarities. By introducing wind and wave data from hindcast surveys and comparing this with the season and trial location it is possible to determine the severity of conditions at the time of trial compared to the average to be expected. These factors were investigated in detail during the course of the study and results obtained for a range of activities; trials with rescue craft or mechanical recovery devices, single or multiple survivor recovery, and recovery at different ranges from the ERRV. Continued data collection and analysis in the future may be used to demonstrate enhanced capabilities of both crew and equipment.

This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author alone and do not necessarily reflect HSE policy.

HSE Books

© Crown copyright 2007

First published 2007

All rights reserved. No part of this publication may bereproduced, stored in a retrieval system, or transmitted inany form or by any means (electronic, mechanical,photocopying, recording or otherwise) without the priorwritten permission of the copyright owner.

Applications for reproduction should be made in writing to:Licensing Division, Her Majesty’s Stationery Office,St Clements House, 2-16 Colegate, Norwich NR3 1BQor by e-mail to hmsolicensing@cabinet-office.x.gsi.gov.uk

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CONTENTS

GLOSSARY iv

1 INTRODUCTION 1 1.1 PREAMBLE 1 1.2 REPORT STRUCTURE 1

2 BACKGROUND 3 2.1 EQUIPMENT DEVELOPMENT 3 2.2 PERFORMANCE STANDARDS 4 2.3 ENVIRONMENTAL FACTORS AFFECTING PERFORMANCE 4

3 METHODOLOGY 7 3.1 DATA SOURCES 7 3.2 PRE-ANALYSIS MANIPULATION 9

4 DATA ANALYSIS 13 4.1 OVERVIEW 13 4.2 DETAILED ANALYSIS 15

5 SUMMARY OF RESULTS 33

6 DISCUSSION 34

APPENDIX 1 AVERAGE PERCENTAGE EXCEEDENCE DATA FOR AREAS OF UKCS 37

APPENDIX 2 RESULTS OF DETAILED ANALYSIS 47

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GLOSSARY Throughput this report a number of acronyms have been used. Though in common use in the marine and offshore industry it will be of benefit to list and explain their meaning. BF Beaufort force CNS Central North Sea DC Daughter craft DTI Department of Trade and Industry ERRV Emergency response and rescue vessel FPSO Floating production, storage offshore FRC Fast rescue craft Hs Significant wave height IS Irish Sea MODU Mobile offshore drilling unit MRD Mechanical recovery devices NNS Northern North Sea PFEER Prevention of Fire and Explosion and Emergency Response Regulations, 1995 S Wave steepness SBV Stand-by vessel SNS Southern North Sea TP Wave period UKCS United Kingdom Continental Shelf WofS West of Shetlands

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EXECUTIVE SUMMARY Over the last several years a large body of data have been collected during trials of rescue craft and other survivor recovery equipment on the UKCS. Primarily the information was collected during the course of validation trials by independent parties, usually on behalf of duty holders, that contract ERRVs to provide offshore oil and gas installation support as part of their EER plan. More recently the ERRV themselves have begun collecting similar information, albeit not exactly the same in scope or detail, under an initiative developed by their industry association. This report concerns an assessment of the data collected by the two sources, supplements it where necessary with the results of other HSE sponsored studies, and analyses the results. Initial work required the transcription of data from paper forms followed by some manipulation of the raw datasets to remove inconsistencies in recording, standardise the style of presentation and replace information that could identify individual vessels/installations with more generic terms. Merging of supplementary information from other sources was carried out to add value to the raw data and facilitate a wider range of analyses than would otherwise be possible. At the highest level data were available from a total of 4347 trials covering DC, FRC and MRD use, although in most cases the data were placed in subsets to ensure analyses were carried out on a more like for like basis. A limited number of records were removed from the datasets prior to some analyses because of missing parameters. Though data were not gathered from all ERRV on the UKCS the dataset is believed to be representative of the practice and conditions of the whole fleet. In respect of ERRV each of the main former vessel types are represented in the dataset, i.e., former anchor handler, supply and fishing vessels as well as trials carried out on a number purpose built ERRV. The dataset also represents a wide range of equipment levels as vessels both with, and without, the constant tension facility for their rescue are included. At least some trials were carried out in each of the main areas of the UKCS though the majority occurred in the northern and central North Sea; in percentage terms there were only approximately 6% of trials in the southern North Sea, Irish Sea and west of Shetlands combined. Perhaps skewed by dataset ‘A, which was collected between February and October 2005, it is apparent that many more trials were conducted in the summer months than at other times and consequently the environmental conditions for the trials tends more towards benign than severe. Moreover, when assessing the date of trials against the Hs it can be concluded that, with the passage of time, there appears to be just the same likelihood of trials being conducted in lesser sea states in recent months than there was several years ago. With the witnessed trials this may have occurred because of the need to schedule trials some time in the future when of course the weather can not be planned; it is what it is on the day of the trial and in many cases this turned out to be ‘good’. There was found to be a little bias towards purpose built ERRV carrying out more trials than their proportion of the whole ERRV fleet would suggest. Furthermore, ERRV fitted with constant tension equipment also tended to carry out more trials than those not fitted. Incorporation of weather exceedence data to the trials data was done to assess how ‘bad’ the wind and Hs were in a particular location when trials were conducted compared to the average maximums for that area. This analysis was carried out on a number of levels; using the whole dataset of rescue craft trials at the highest level down to a detailed examination of the type of rescue equipment in each area of the UKCS. At the general level the analysis revealed that approximately 70% of all trials were conducted in wind and Hs conditions that were up to 50% of the average maximum. Further, that when weather conditions were more than 90% of the average maximum then fewer than 5% of trials were carried out. At the detailed level the situation was found to differ markedly though it is likely this occurred because of the relatively small number of trials carried out in some sea areas of the UKCS.

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Analysis of the data in respect of the time taken for rescue and recovery trials to be conducted highlighted the difficulty of attempting to make definitive judgements of how long survivor recovery will take. Even based on validated trials it is apparent that some of the results were perverse and contradict accepted wisdom, particularly in terms of the expected recovery times increasing as the weather deteriorates and as the distance from the ERRV increases. While highlighting the difficulty of providing anything other than indicative average times for survivor recovery in known weather conditions it was found to be impossible to make predictions on how long recovery may take in more adverse weather beyond the scope of the trials. Simple extrapolation of the results to higher sea states was found to be invalid and, even if the results of this had appeared satisfactory, they would fail to take into account many other factors that could influence performance such as wave steepness, modernity and fitness for purpose of equipment, and crew training and competence. Overall the trials dataset is a useful source of information and one that could become more valuable if data continue to be added. Further value could be added to the data if it were expanded slightly, perhaps to indicate the time of day that the trial was carried out.

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1 INTRODUCTION 1.1 PREAMBLE

This report has been prepared by Maritime Data Solutions LLP on behalf of the Offshore Division of the Health and Safety Executive. The report details the results of an analysis of a large body of trials data conducted with different types of equipment used in offshore rescue and the effects of adverse weather conditions on their use. The trials data includes equipment used by emergency response and rescue vessels (ERRVs), fast rescue craft (FRC), daughter craft (DC) and mechanical recovery devices. For offshore oil and gas installations on the United Kingdom Continental Shelf (UKCS), UK legislation requires those companies that are responsible for the safety of their offshore installation workers (Duty Holders) to ensure adequate arrangements are in place to secure a ‘good prospect of recovery and rescue’. In particular, the Regulation 17 of Prevention of Fire and Explosion and Emergency Response, 1995 (PFEER) states that:

“The duty holder shall ensure that effective arrangements are made which include such arrangements with suitable persons beyond the installation, for: i) Recovery of persons following their evacuation or escape from the installation and ii) Rescue of persons near the installation and iii) Taking such persons to a place of safety And for the purposes of this regulation arrangements shall be regarded as being effective if they secure a good prospect of those persons being recovered, rescued and taken to a place of safety.”

The regulations are goal setting in nature and not prescriptive. In the development of these procedures the Duty Holder must be able to show that properly trained crew are using suitable equipment and that satisfactory response times can be obtained in practice. The main aim of this research is to analyse the results from a large number of trials using various rescue equipment in use on the UKCS and highlight any trends that may be apparent. Further, to incorporate other complementary sources of information to determine the actual levels of performance being achieved in different environmental conditions and compares these with the parameters to be expected in those areas. 1.2 REPORT STRUCTURE

Section 2 provides background to the development of vessels used for standing by offshore oil and gas installations on the UKCS together with information on the type of equipment used for the rescue and recovery of survivors from the water. It also outlines a possible approach to goal setting for the environmental conditions up to which rescue craft trials could be carried out.

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A description of the data used for analysis, both the trials data from two sources and supplementary information used to add value to the trials data, are described in Section 3. This section also details the data manipulation that occurred prior to analysis. Information on data analysis is presented in Section 4 in a largely graphical manner such that the results can be readily assimilated. Explanatory text has been included as appropriate. Tables and figures of results in this section tend to be of a general nature insofar as they assess the results of trials across all areas of the UKCS. More detailed charts, at the level of specific areas and types of equipment, are presented in appendices. A brief discussion on the implications of trials data gathering and the results of the analysis are presented in Section 5.

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2 BACKGROUND 2.1 EQUIPMENT DEVELOPMENT

Since the earliest development of the UKCS in the 1960’s much of the emergency response strategy for both fixed and mobile installations has been built around the capabilities of so-called Stand-by Vessels (SBV) (more recently termed Emergency Response and Rescue Vessels (ERRV's). In the early days of UKCS operations many of the SBV were former fishing vessels, converted for their new role to a greater or lesser extent, and were possibly not entirely suited to their new purpose. As the UK offshore industry became more mature so the need to have better equipped SBV to service the growing number of installations increased. This led to the deployment of larger and more manoeuvrable vessels, many of which were converted from either platform supply or anchor handling vessels. More recently a number of the older hulls have been replaced by purpose built vessels that combine good manoeuvrability, enhanced survivor reception and medical after-care facilities, state of the art navigational/communications equipment and rescue craft capable of operating in more severe weather. Changes to the design and equipment of modern ERRV has also led to an expansion of their activities beyond providing a rescue/recovery and collision risk warning function as was the case for a number of years. Many ERRV, whether purpose built or not, now undertake in-field transfers of personnel or stores whereas some ‘multi-role’ vessels have been designed to perform other tasks such as tanker assistance or cargo transfer to/from shore in additional to their more traditional safety function. For their fast response capability many ERRV are fitted with both DC and FRC, the former being capable of a degree of autonomy from the mother vessel within the constraints of operating limits assigned by the Maritime and Coastguard Agency. In many respects the launch/recovery phases of both FRC and DC are the limiting factors to their use and especially the recovery operation when the craft may be heavier with survivors on board or having shipped water. Of particular concern is the difficulty that crew may experience when attempting to re-attach the rescue craft’s fall(s) in a seaway. The adoption of single point lifting apparatus made connection much quicker and less fraught than with double falls but even so the recovery still required a high degree of professionalism and teamwork between the craft’s crew and those operating the davit on board the ERRV. A major step in extending the operating envelope of rescue craft came with the introduction of ‘constant tension’ equipment on davits. The use of this equipment reduces the possibility of injury to rescue craft crews and damage to boats through removing the susceptibility of ‘snatch’ when a fall becomes slack and then bears the full weight as a craft is first lifted on a wave or swell peak and then falls into a trough. With constant tension engaged a fall winch pays out or heaves to keep a limited tension on the fall until ready for hoisting which can then be done quickly and seamlessly. However, in some cases the weather conditions will be too severe to launch/recover rescue craft and in these circumstances ERRV are provided with a mechanical recovery device to recover survivors directly from the sea. A number of such designs are available though the most common on ERRV on the UKCS is the Dacon Scoop. The equipment is a crane operated rescue net for recovery of casualties from the water directly on board rescue vessels.

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2.2 PERFORMANCE STANDARDS

Obviously, providing the most effective rescue and recovery equipment is only part of the overall strategy and goes hand in hand with proper and on-going training for ERRV crews. To satisfy themselves that a ‘good prospect of rescue and recovery’ can still be achieved Duty Holders require frequent drills to be carried out on their contracted ERRV and some have set performance standards in terms of the significant wave height (Hs) up to which it ought to be possible to effect successful rescue craft launch/recovery activities. Although a number of Duty Holders have adopted 3.5m Hs as their upper limit benchmark for rescue craft trials it is perhaps a less relevant measure for all areas of the UKCS because some areas, especially in the southern North Sea, infrequently experience such severe conditions and therefore it would be difficult for the ERRV to demonstrate they could achieve that standard. A more appropriate measure may be to consider using hindcast wind and wave time series data to produce wind and wave frequency distributions and from these percentage exceedence tables to determine the proportion of time the wind speed or wave height exceeded any given value. Armed with data on the average ‘worst’ weather in a particular area it would then be possible to deduce a percentage value up to which it ought to be possible to carry out drills. This approach would be more focused to distinct areas and based on pertinent historical data rather than the somewhat arbitrary and ‘one size fits all’ regime currently in use. Regardless of the severity of the weather conditions in which trials are carried out, even if they are consistently up to 100% of the worst expected, there is always the possibility that a rescue craft may be called upon in even worse weather. In these circumstances the ‘theoretical’ maximum launch conditions have to be relied upon which, may be subjective at best and guesswork at worst. When operating in conditions beyond which regular trials and drills have been carried out those involved begin to have to rely on good luck to achieve a successful outcome. Previous HSE sponsored studies1,2 have assessed rescue craft limits of operability in ‘rough weather’ from a largely theoretical perspective and should be consulted for further information as such activities are beyond the scope of this trials data analysis. In the context of their work rough weather is taken to mean the conditions in which training and practice for an emergency situation are not normally carried out for safety reasons. 2.3 ENVIRONMENTAL FACTORS AFFECTING PERFORMANCE

Weather conditions experienced on the UKCS can be some the most hostile in the world. In general the predominant wind direction is from the south-westerly quadrant with the winter season experiencing more severe weather conditions than the summer, although it is possible for adverse weather to be experienced at any time of year and from any direction. Several studies have attempted to quantify the operational limits for FRC/DC operations and concluded that definitive levels are extremely difficult to determine and depend on several circumstances, the greatest of which are the Hs and wave steepness. Although wind speed is also a measure which is often cited when assessing launch capability, in reality it is of much less a consideration than Hs. However, what these factors do, to one extent or another, is to offer a quantifiable measure of how ‘bad’ conditions are at a particular location.

1 “Rough Weather Rescue”, WS Atkins Consultants Ltd., OTO01089, 2002 2 “Effect of Weather on Performance and Response Times in Offshore Rescue, WS Atkins Consultants Ltd., OTO99006, 1999

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The nature of the UKCS, with large areas to the north-west and south-west being exposed to oceanic wave spectra, with other areas to the east of the Britain and between Britain and Ireland being more sheltered and with wide variations in water depth, causes profound differences in the type of sea conditions. In the southern North Sea the significant wave height is composed mainly of wind driven waves whereas in the northern North Sea and to the west of the Shetlands it is likely to be swell waves. This casts further doubt on the possibility of using a single parameter to state with certainty whether rescue craft operations should be possible in all areas. 2.3.1 Significant wave height Significant wave height is the most popular and widely used parameter in attempting to determine the minimum operational limits for rescue craft activities. It is defined as the mean height of the highest one third of waves and is a measure of the total energy in the wave spectrum. The total wave can be considered to come from two sources; wind waves and the swell. Wind waves are locally generated waves that can have a wide range of directions and can cause a highly irregular sea surface. Swell is formed as a result of wind elsewhere and can have originated a great distance away. The swell wavelength is much longer than that of wind waves and the period is also greater. In general, swell wavelength and period increase with time and with the distance from their source. Although the wind and wave components of the Hs will be a factor in all sea areas of the UKCS, the relative size of these components will differ from place to place. In the southern North Sea for example, the wind waves are likely to produce most of the Hs because there is little fetch and hence swell (except possibly from the north), whereas to the west of Shetlands the Hs could be made up primarily of swell unless there are local storm conditions to produce wind waves. 2.3.2 Wave steepness Although Hs is the common performance measure when considering whether it ought to be possible to carry out rescue craft operations, a better indication may well be the wave steepness (S). While it is possible to represent this in a number of scientific ways such as relating it to the water depth, in simple terms this is the ratio between the wave height and the wavelength. although it can also be determined from the wave period (TP), such that:

S = 2πHs/gTP2 (where g = 9.81ms-2) 2.3.3 Wind speed Wind, whether local or at some distance away, is responsible for the generation of surface wind waves and swell. Factors that affect wave development are the wind speed, the distance over which the wind has blown, the time that the wind has been blowing, the water depth and the relative direction of tidal stream and current to the wind. 2.3.4 Effect of wind and waves The sub-sections above present an overview of typical weather conditions on the UKCS. In practical terms the result of these may be described with the following simple effects: • Generally, the operation of rescue craft is likely to be affected more by wind waves than by

swell; • Wind speed alone, although easy to determine by rescue vessel crews, is not a reliable

indicator of likely conditions to be experienced. Further, wind speed has less of an effect on the operation of rescue craft, especially FRC, than the effects of waves and swell;

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• Wave steepness is likely to be more location specific than simply considering wave height. Differences in wave steepness could enable a successful launch/recovery in one area whereas it could be prevented in another even though both have the same wave height;

• Conflicting current and wind directions will cause a steepening of the seas.

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3 www.dbd-data.co.uk/bb2001/book

3 METHODOLOGY 3.1 DATA SOURCES

This report describes the results of analysis of two separate sources of rescue equipment trials, as described below in sub-sections 3.1.1 and 3.1.2. Unfortunately, during detailed analysis of both sources it became apparent that the scope of the results may be somewhat limited by the level of detail in some areas. In some respects this is an understandable shortcoming insofar as minimising the reporting burden on ERRV officers should take precedence over the possibility of the crew’s perception of gathering information just for the sake of it. On balance these conflicting priorities appear to have been treated sympathetically although in future those involved in organising the data gathering may wish to consider slightly altering the question set away from the hardware involved and replacing it with more on the location and circumstances of the trial. In particular some information on the time of day when trials are commenced could be beneficial to any further analysis as would details of their duration, the number and range from which targets were recovered and the method by which this was achieved. Notwithstanding a lack of some data fields that could yield valuable insights into the conduct of rescue drills, it was found to be possible as well as desirable to combine the two trials data sets with information from other sources to supplement and add value, as described in sub-sections 3.1.3 to 3.1.5. 3.1.1 Dataset ‘A’ An initiative to promote and raise standards within the ERRV industry led to the gathering of information from vessels about rescue craft operations. Over the period from 30 January 2005 to 11 October 2005 a large quantity of hard copy data were collected by deck officers from a number of vessels in most areas of the UKCS. A total of 203 reports, each containing multiple records, was collated centrally within the UK and passed to Serco Assurance for entry into an electronic database. 3.1.2 Dataset ‘B’ As part of some Duty Holders’ quality management systems some trials involving ERRV rescue equipment are independently witnessed and verified by surveyors usually appointed by either the Duty Holder of ERRV operator. The results of the trials are then analysed to verify that an adequate level of performance is being achieved and are sometimes used as a basis for extrapolation to more severe conditions such as those beyond normal experience. Over the period from January 1999 to June 2004 a large number of such trials were witnessed and the results used to compile dataset ‘B’. On the whole the data were found to be extremely pertinent, broad in scope and in sufficient detail to enable a wide range of analyses to be carried out. 3.1.3 ERRV Database - ProMarine Under a HSE research contract in 2001 Promarine, Aberdeen produced a database of the ERRV in use on the UKCS; their technical specification, types and location. The outcome of the study yielded a database of 151 ERRV, all of which carried FRC, 43 additionally carried DC, 148 were fitted with a Dacon Scoop and 3 vessels carried a Sealift Basket. 3.1.4 “Development of UK Oil and Gas Resources 2001”3 (ISBN 0-11-515479-5) Field name and geographical information in terms of block and sub-block numbers were drawn

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4 “Wind and Wave Frequency Distributions for Sites Around the British Isles, Fugro GEOS, OTO01030, 2001

from this Department of Trade and Industry (DTI) publication, also known as the “Brown Book” and then assigned to a geographical area of the UKCS, i.e., West of Shetlands (WofS), Irish Sea (IS) and either northern, central or southern North Sea, respectively, (NNS), (CNS) or (SNS), to facilitate comparison with the weather exceedence data described in sub-section 3.1.5. 3.1.5 Fugro GEOS (OTO010304) The report from this project presents various wind and wave frequency information for 28 sites around the British Isles. The results were produced using hindcast wind and wave time series data from the NEXT model by combining periods from January 1977 to December 1979 and January 1989 to December 1994. Although the report contains much valid and useful information, of particular relevance to the analysis of ERRV data is the average monthly and average annual percentage exceedence distributions of mean wind speed and Hs. By utilising the average of the results, which may have been presented for up to 8 points, of a particular area of the UKCS it was possible to assess these against data recorded in datasets ‘A’ and ‘B’ to indicate ‘how bad’ the wind and Hs were at the time of trial compared with the ‘normal’. Table 1 presents information on the NEXT data points used for this study. To place the table in context Figure 1, overleaf, graphically represents the location of the data points on the UKCS.

Table 1 NEXT data points

NEXT data point

Area Latitude Longitude NEXT data point

Area Latitude Longitude

14212 NNS 61° 30.42’N 0° 56.52’E 15143 CNS 55° 33.90’N 2° 15.00’E 14376 NNS 60° 30.78’N 0° 51.78’E 15321 CNS 55° 23.46’N 0° 15.78’E 14651 NNS 59° 23.34’N 0° 42.78’W 15327 SNS 54° 26.28’N 2° 30.78’E 14541 NNS 59° 21.72’N 1° 13.50’E 15447 SNS 54° 19.92’N 1° 13.74’E 14594 NNS 59° 18.00’N 0° 28.50’E 15571 SNS 53° 35.22’N 1° 25.32’E 14773 NNS 58° 28.38’N 0° 00.48’W 15631 SNS 53° 31.74’N 0° 47.82’E 14832 NNS 58° 24.24’N 0° 43.98’W 15512 SNS 53° 28.80’N 2° 24.30’E 14715 NNS 58° 22.68’N 1° 08.52’E 15697 SNS 52° 31.68’N 2° 18.24’E 14897 CNS 57° 23.88’N 1° 03.84’E 15920 IS 53° 44.46’N 3° 48.30’W 14956 CNS 57° 20.16’N 0° 21.72’E 16230 IS 52° 30.18’N 5° 31.44’W 15194 CNS 56° 44.88’N 1° 34.98’W 14318 WofS 61° 22.38’N 0° 40.20’W 15138 CNS 56° 21.66’N 0° 18.66’E 14533 WofS 60° 36.24’N 2° 24.00’W 15021 CNS 56° 19.14’N 2° 03.84’E 14703 WofS 60° 11.46’N 4° 13.56’W 15318 CNS 55° 51.00’N 0° 54.66W 14824 WofS 59° 34.74’N 4° 18.90’W

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Figure 1 NEXT data points on the UKCS

3.2 PRE-ANALYSIS MANIPULATION

3.2.1 Dataset ‘A’ On receipt by Maritime Data Solutions the data were standardised to remove inconsistencies, i.e., where wind and wave directions were reported by quadrant they were converted to three digit angular measure clockwise from North, and transferred to spreadsheets for ease of analysis. Several fields within the dataset were further rationalised by incorporating a series of

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‘bins’ and assigning the data in the record into one of the bins, for example wind speeds were grouped into <10 knots, 10 - <20 knots, 20 - 30 knots and >30 knots. Data ‘binning’ was necessary to facilitate data analysis and also occurred in the following data fields:

Table 2 Binning of dataset ‘A’

Bin 1 2 3 4

Significant wave height (m) <1 1 - <2 2 - 3.5 >3.5 Wave period (secs.) <5 5 - 10 >10 - Swell height (m) <1 1 - <2 2 - 3.5 >3.5

A field within the dataset entitled ‘Visual Max Sea Height and Period’, apparently as a measure of wave steepness, appeared to be somewhat misunderstood by those completing the forms because there was a wide disparity in the information provided in this field. However, it was possible to calculate the same information using the Hs and wave period (TP), using the formula described in sub-section 2.3.2. By cross-referencing information in the ERRV Database (described in sub-section 3.1.3) and the Brown Book (sub-section 3.1.4) with dataset A, it was possible to easily build up the level of detail in the dataset ‘A’ so as to be similar to that in the dataset ‘B’. Although the dataset contains information about the ERRV involved and the installation which it guarded these details were not used as they were felt to be too specific. Instead, ERRV were each assigned a unique numerical identifier and were grouped according to their former type, i.e., former anchor handler, fishing, supply or purpose built, and the fixed installations grouped according to their location, i.e., WofS, NNS, CNS, SNS, IS. It should be noted that in the absence of location information for mobile offshore drilling unit (MODU) is was not possible to assign the records to an area where the installation guarded was of this type. In addition to binning the Hs to facilitate analysis it was also found necessary to ‘round up’ to the nearest half metre to concur with the data extracted from OTO01030. On the whole it was found that the majority of Hs details had already been recorded in 0.5m increments but that a small number had not. So as not to artificially diminish the conditions under which trials had been conducted it was decided that where a precise figure of Hs had been recorded rather than a whole or half metre then these would always be amended to the next higher category, i.e., 1.1m to 1.5m and 2.6m to 3.0m, etc. 3.2.2 Dataset ‘B’ Data ‘binning’ occurred in several fields:

Table 3 Binning of dataset ‘A’

Bin 1 2 3 4 5 6 7 8 9 10 Significant wave height (m) <1 1-<2 2-3.5 >3.5

Distance to casualty (miles) <1

1 - 1.99

2 - 2.99

3 - 3.99

4 - 4.99

5 - 5.99

6 - 6.99

7 - 7.99

8 - 8.99 >=9

Rounding up of Hs was carried to concur with data presented in OTO01030 as described above.

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3.2.3 Fugro GEOS (OTO01030) Data were extracted from the appendices of OTO01030. In particular, data from the tables of percentage exceedence distributions for mean wind speed and Hs for each of the data points detailed in Table 1 were imported into a spreadsheet for analysis. As explained in the report (page 13), the data present “…. a cumulative distribution of occurrences. The results are expressed as percentages, that is the percentage exceedence of the given speed or height. The percentage exceedence table may therefore be used to determine the proportion of time the wind speed or wave height exceeded any given value.” Initial analysis took the form averaging, for each data point in a particular UKCS area, the percentage exceedence figure for each 0.5m Hs interval during the relevant month. This approach was found to be necessary because the data recorded in dataset ‘B’ refers only to the geographical area and not individual installations. Although dataset ‘A’ has been supplemented by block and sub-block numbers derived from the installation name and therefore does lend itself to comparison with the closest NEXT data point listed in Table 1, to concur with the method used for dataset ‘B’ an average of the whole area was used. In essence, averaging the data contained in the individual Hs tables for each area of the UKCS produces a single table that can be considered representative of that area as a whole. Obviously this approach may lead to slight discrepancies if the data points contained in OTO01030 are not representative of the whole area, or if some of the trials were carried out in areas that were atypical. This is the case in dataset ‘B’ trials conducted close to Aberdeen that were classed as CNS. Nonetheless, this approach is considered to have yielded the most accurate results consistent with raw data accuracy and robustness. A similar approach to that described for averaging the Hs was used to deal with the mean wind speed and produced a single table of percentage exceedence distribution of mean wind speed for each area of the UKCS. However, because the wind data in OTO01030 were based on the Beaufort force (BF) rather than in knots as datasets ‘A’ and ‘B’ both were, it would be unwarranted and less accurate to amend the majority of the trials data to concur with the BF. In these circumstances it was decided to incorporate new rows in the wind exceedence tables at 1 knot intervals between the existing figures and for these to be populated with data based on a linear interpolation between those originals. For example, in the NNS during January the average percentage exceedence data for BF5 (17 knots) is 79.10% and for BF6 (22 knots) is 59.44%; interpolating between these figures produces:

Knots BF Percentage exceedence17 5 79.10 18 - 75.17 19 - 71.23 20 - 67.30 21 - 63.37 22 6 59.44

Similar data interpolation occurred to produce a wind exceedence table for each area of the UKCS between 0 -–64 knots at 1 knot intervals. Tables of the ‘average’ percentage exceedence data for mean wind speed and Hs for each area of the UKCS, data that were used as the basis for a number of analyses, are presented in Appendix 1.

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4 DATA ANALYSIS 4.1 OVERVIEW

4.1.1 Dataset ‘A’ The dataset contains a total 2819 records made up of reports from 55 vessels (one vessel changed name during the study and reported under two different names) composed thus:

former Anchor handler 7 (12.7%) former Fishing 8 (14.5%) Purpose built 15 (27.3%) former Supply 25 (45.5%)

In terms of geographical location across the UKCS the distribution was:

Northern North Sea 642 records (22.8%) Central North Sea 1030 records (36.5%) Southern North Sea 26 records (0.9%) Irish Sea 75 records (2.7%) West of Shetlands 51 records (1.8%) Not Recorded 995 records (35.3%)

There was found to be wide disparity between the number of records from different vessels. The vessel conducting the most trials had done so by a margin of over 37% above that with the second highest number. On average each vessel had carried out slightly over 50 trials, a figure that was slightly above the median value (48.5).

Table 4 Number of dataset ‘A’ trials carried out by each ERRV

ERRV identifier No. of trials

ERRV identifier No. of trials

ERRV identifier No. of trials

3 132 48 59 6 34 45 96 15 58 35 32 17 95 34 57 20 31 52 91 30 56 28 31 7 91 19 52 47 31

31 86 40 52 12 29 14 85 23 51 26 28 49 85 Average 50.3 43 28 51 85 39 50 25 26 22 77 13 49 16 25 46 77 55 48 11 23 27 75 33 47 53 22 54 70 32 44 50 20 36 69 42 43 1 18 41 65 37 39 Not Recorded 16 44 65 21 37 18 15 38 60 29 37 10 13 9 60 5 36 2 12 4 59 8 35 24 12

The reporting ERRV were in attendance at 43 fixed installations/FPSO (1819 records) and 19

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MODU (582 records). This information was not provided on the data reported by 14 vessels (418 records). It should be noted that some vessels rotate among a number of installations/MODU and therefore some have reported as guarding more than one. Trials were conducted using FRC on 2283 occasions and with DC on 520 occasions. It was not possible to determine this information on 16 records. NB: Although it would have been theoretically possible to incorporate data from ProMarine of which ERRV may be fitted with constant tension equipment for their rescue craft it was decided not to pursue this. This is because even though a vessel may not been have been so equipped in 2001, in the interim it could have been retrofitted and the results would have been misleading. 4.1.2 Dataset ‘B’ The dataset contains a total of 1528 anonymous records comprising 6 different trials categories within a series of spreadsheets:

355 trials using “mechanical recovery devices” (MRD) to rescue up to 21 targets per incident. 635 trials involving “rescue craft” to recover single or small (generally less than 5) numbers of targets. 207 trials when responding to mass targets (generally 15 or more) from a “helicopter incident” using MRD. 163 trials under “mass escape” conditions using MRD where generally 20 or more targets were involved. 87 trials involving up to 2 “rescue craft” to recover between 12 and 21 targets from a “helicopter incident”. 81 trials involving up to 2 “rescue craft” to recover between 10 and 30 targets from a “mass escape”.

For the purposes of data analysis the dataset involving rescue craft (803 records) was separated from trials involving MRD (725 records) as it is felt the latter were likely to have been used in more severe sea conditions. Their inclusion in the whole dataset may well have skewed the results. From the data it was not possible to determine whether the “rescue craft” involved in individual trials was either FRC or DC as no distinction was made between the two craft types. The ERRV fleet data contains information on the type, capacity and whether constant tension equipment is fitted for 98 vessels. However, trials were not carried out on 18 vessels and therefore the dataset is compiled from trials on 80 ERRV, composed thus:

former Anchor handler 21 (26.3%) former Fishing 11 (13.7%) Purpose built 22 (27.5%) former Supply 26 (32.5%)

A number of ERRV are known to be fitted with constant tension equipment to aid in launch and recovery operations although in almost all occurrences on the UKCS such facilities are used in conjunction with DC operations rather than with FRC. Of the foregoing the breakdown of vessels fitted with constant tension equipment are: Fitted Not Fitted Not Recorded

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former Anchor handler 8 (38.1%) 9 (42.9%) 4 (19.0%) former Fishing 0 (0%) 8 (72.3%) 3 (27.3%) Purpose built 7 (31.8%) 9 (40.9%) 6 (27.3%) former Supply 1 (3.8%) 21 (80.8%) 4 (15.4%)

Trials were conducted at the following locations on the UKCS:

Northern North Sea 499 records (32.7%) Central North Sea 930 records (60.8%) Southern North Sea 67 records (4.4%) West of Shetlands 32 records (2.1%)

Once again there was a wide disparity between the number of records from different vessels. On average each vessel had carried out slightly over 19 trials although the median values were much less; 4 for MRD trials, 2 for rescue craft trials and 6 overall.

Table 5 Number of dataset ‘B’ trials carried out by each ERRV

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MRD trials

Craft trials

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MRD trials

Craft trials

TOTAL ERRV identifier

MRD trials

Craft trials

TOTAL

54 46 128 174 17 9 0 9 86 3 1 4 47 69 74 143 43 5 4 9 18 3 0 3 57 67 67 134 58 7 2 9 25 2 1 3 29 44 56 100 74 7 2 9 39 1 2 3 79 47 44 91 13 6 2 8 60 2 1 3 45 45 42 87 85 6 2 8 66 2 1 3 42 38 45 83 40 4 3 7 92 3 0 3 50 28 46 74 49 4 3 7 93 1 2 3 37 32 34 66 71 7 0 7 95 2 1 3 82 15 49 64 77 0 7 7 6 2 0 2 48 7 33 40 81 3 4 7 9 2 0 2 84 16 13 29 89 4 3 7 21 2 0 2 53 6 22 28 97 7 0 7 33 0 2 2 5 6 17 23 51 4 2 6 61 2 0 2

91 12 9 21 59 4 2 6 65 0 2 2 Average 9.1 10.0 19.1 63 4 2 6 69 0 2 2

52 13 5 18 88 4 2 6 78 2 0 2 4 5 12 17 90 0 6 6 2 1 0 1

16 17 0 17 8 4 1 5 62 1 0 1 55 11 4 15 10 3 2 5 67 1 0 1 34 10 4 14 14 3 2 5 70 0 1 1 7 11 0 11 15 4 1 5 72 0 1 1

12 5 6 11 26 3 2 5 73 1 0 1 19 8 3 11 68 2 3 5 75 0 1 1 23 7 3 10 41 1 3 4 76 1 0 1 31 6 4 10 46 2 2 4 80 1 0 1 83 9 1 10 64 3 1 4 87 0 1 1

4.2 DETAILED ANALYSIS

After pre-analysis manipulation datasets ‘A’ and ‘B’ were both subjected to a wide array of tests to determine whether any trends existed. In most cases it was possible to subject both datasets to

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the same tests although this was not the case with assessing the recovery of ‘targets’ in dataset ‘A’ as this information had not been gathered. This section of the report presents the results of analyses in a broad sense and refers to the various appendices where much of the detail is presented. Supporting contextual information as appropriate is highlighted in the relevant sub-sections below. 4.2.1 Trials by season and Hs An indication of the time of year and prevailing Hs conditions when trials were conducted. The analysis split the dataset into the month of the trial and further categorised each trial according to the Hs. Figure 2 results from combining all records in datasets ‘A’ and ‘B’; a total of 4200 trials where the information was available.

Figure 2 Trials by month and Hs It is clearly demonstrated that many more trials have been carried out during the summer months that in the rest of the year although it is highly likely that the figures are skewed in this manner because the majority of dataset ‘A’ trials were carried out during these months. The chart also shows, as would be expected during summer, that most trials were conducted in the relatively benign conditions of less than 2.0m Hs. These analyses were also performed separately on dataset ‘B’ for rescue craft and MRD and on dataset ‘A’ for FRC and DC. The results are presented in Appendix 2, Section 1 and highlight that dataset ‘B’ MRD trials are carried out fairly consistently across the year whereas those involving rescue craft tend to occur during the summer months.

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The same information can be also presented in a different manner to demonstrate the actual Hs conditions (i.e., not ‘binned) and date. Figure 3 shows a reasonably consistent level of Hs severity during trials over the course of several years; data points prior to June 2004 indicating dataset ‘B’ trials whereas those after this date represent dataset ‘A’.

Figure 3 Trials by date and Hs It can be concluded from this that trials were just as likely to be carried out in lesser sea states more recently as they were several years ago and that there was no gradual worsening of trial conditions to demonstrate improved capability. Such a situation would have been demonstrated by an increasing number of data points towards the middle and top of the chart the further from the left axis. Of course it is quite probable that the decision to conduct supervised and validated trials is made some time earlier without regard to the likely severity of weather and the conditions on the day are merely happenstance. Data points post-June 2004 are predominantly clustered towards the bottom of the chart indicating a preponderance of trials having been undertaken in less severe sea conditions though no other discernible trends were apparent because of the relatively short period during which data were collected. A similar analysis to that in Figure 3 was also performed separately for rescue craft and MRD trials of dataset ‘B’ and on FRC and DC trials of dataset ‘A’. The results are presented in Appendix 2, Section 1 though the conclusions from the charts are broadly similar to those of the whole dataset. 4.2.2 Trials on former vessel types by Hs Analysis was carried out based on the former vessel type together with the prevailing Hs conditions when trials were conducted. The investigation split the dataset into the four former vessel types and further categorised each trial according to the Hs.

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The results of this analysis are presented in Figure 4 and come from combining all records in both datasets ‘A’ and ‘B’ where the information was available; a total of 4184 trials.

Figure 4 Trials by former vessel types and Hs The chart indicates there is no particular bias towards trials being carried out more on one former vessel type than another with worsening Hs conditions. For example, although it may be expected that former fishing vessels may have proportionally not undertaken as many trials in higher Hs conditions than purpose built vessels because of perceptions that the latter may be better equipped, this was not the case. Overall, less trials were conducted in Hs = 2m – 3.5m than in Hs = 1m – 2m but this was due to a proportionate reduction in the number of trials on each of the four former vessel types rather than it being accounted for in only one or two types. These analyses were also performed separately on rescue craft and MRD trials of dataset ‘B’ and for FRC and DC of dataset ‘A’ with broadly similar results as described above. The results are presented in Appendix 2, Section 2. To further explore whether vessel type and equipment levels had any influence on the Hs conditions under which trials had been conducted a separate analysis was made using information on the fitment of constant tension equipment. As previously described in sub-section 4.1.1, it was necessary to exclude dataset ‘A’ records from this analysis as information from ProMarine had not been merged in respect of constant tension. Figure 5 presents a breakdown of the former types of the 62 ERRV comprising the dataset ‘B’ and further identifies the proportion of each type, a) fitted with constant tension equipment, b) not fitted, and c) where fitment is unknown. It should be noted that although the dataset ‘B’ contains trials results from 80 ERRV only 62 vessels were recorded with rescue craft trials and therefore are of interest to this analysis. The remaining 18 had only carried out MRD trials.

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Figure 5 ERRV fleet former types and constant tension equipment fitment

Figure 6 Trials by former types and constant tension equipment utilisation Figure 6 presents a breakdown of the proportion of the 803 rescue craft trials as carried out by

Supply vessel with C/T0.5%

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Anchor handlerwith C/TAnchor handlerwithout C/TFishing vesselwith C/TFishing vesselwithout C/TPurpose builtwith C/TPurpose builtwithout C/TSupply vesselwith C/TSupply vesselwithout C/T

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Anchor handlerwith C/TAnchor handlerwithout C/TAnchor handlerwhere C/T N/RFishing vesselwith C/TFishing vesselwithout C/TFishing vesselwhere C/T N/RPurpose builtwith C/TPurpose builtwithout C/TPurpose builtwhere C/T N/RSupply vesselwith C/TSupply vesselwithout C/TSupply vesselwhere C/T N/R

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the former types of ERRV and whether they were fitted with constant tension equipment, or not, or whether this information had not been recorded. A comparison of Figures 5 and 6 clearly indicates that although the 62 ERRV of dataset ‘B’ are made up of 31% of purpose built vessels, these vessels were responsible for 40.6% of the trials. Conversely, the other three former types of ERRV all carried out a lesser proportion of the trials than their population would suggest although in some cases the difference is minimal. Particularly significant is the proportion of trials (35.5%) carried out on purpose built ERRV fitted with constant tension suggesting that better equipped ERRV are likely to conduct more trials than those fitted with more basic equipment. 4.2.3 Trials in prevailing conditions against those likely This section deals with the number of trials carried out where the prevailing wind and Hs data is compared with that extracted from OTO01030. However, to place the resulting analysis in context it is beneficial to demonstrate the areas of the UKCS where trials were conducted along with the broad categories of Hs (i.e., ‘binned’ data) under which they occurred. Figure 7 results from combining all records in dataset ‘A’ (1722 trials) along with the rescue craft trials from dataset ‘B’ (803 trials). To concur with the methodology for comparing exceedence data, described below, it was decided to exclude the MRD data from dataset ‘B’ from this analysis.

Figure 7 Rescue craft trials by UKCS area and Hs To be noted from Figure 7 is the preponderance of trials carried out in the CNS compared to the fewer trials in other areas. This factor will become more significant when the exceedence data is included insofar as the area where the majority of trials occurred is more likely to experience lesser maximum Hs than the NNS or WofS, for example. Under such circumstances if like for like trials have been conducted in different areas of the UKCS they will yield different exceedence figures and this should be borne in mind. In terms of wind speeds trials in different UKCS areas are less significant than with Hs because the difference in wind speeds between

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areas is much less than with Hs. This is due to the reduced fetch caused by intervening land. Manipulation of the wind and wave exceedence data in OTO01030 into separate ‘average’ tables according to the UKCS area and month (as described in sub-section 3.2.3), produced the tables in Appendix 1. For example, the first table presents percentage exceedence distributions for the NNS which for January (31 days x 24 hours = 744 hours) shows that for 13.26% of the month, (that is 744 x (13.26/100) = 98.65 hours), the mean wind speed was on average greater than or equal to 17.2 m/s (or 34 knots, or Beaufort Force 8). Similarly, in the second table of Appendix 1 the data shows that the Hs was on average greater than or equal to 5.5m for 1.52% of April (720 x (1.52/100) = 10.94 hours). Thereafter, wind speed and Hs data from individual trials from both datasets ‘A’ and ‘B’ were then merged into and compared with data from the relevant exceedence table according to UKCS area and month. By matching the wind speed and Hs of each trial record with that from the relevant exceedence table, a percentage exceedence figure was extracted for that trial. For example, if a trial was conducted in the NNS during September when the prevailing Hs was recorded as 1.5m, the corresponding figure extracted from the table in Appendix 1 was 63.29%. This means that at the time of the trial the prevailing Hs or less could be expected to occur for almost two-thirds of the time during the month. For the whole dataset the individual results obtained in this fashion were then grouped (rounded up or down) at 1% exceedence intervals and counted to deduce the number and percentage of trials carried out at 1% intervals of the average maximum Hs and wind speed. The results of this analysis are presented in Figure 8 and come from combining all records in dataset ‘A’ where the necessary information was available (1689 trials) along with the rescue craft trials from dataset ‘B’ (796 trials). It was decided to exclude the MRD trials from this analysis to avoid skewing the results although the MRD trials were assessed separately with the results presented in Appendix 2, Section 3.1.

Figure 8 Percentage of all rescue craft trials carried out in percentage of average maximum wind speeds

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To aid interpretation of the chart it should be remembered that the chart refers to ‘exceedences’, the ‘y’ axis increases from 0% (i.e., zero craft trials) up to 100% (all craft trials) whereas the ‘x’ axis refers to the percentage of the average maximum wind speed, so if the average maximum wind speed for a given area was 50 knots then 10% would be 5 knots, 60% at 30 knots and so on. In practice it is less cumbersome to refer to percentages of the maximum rather than to an absolute wind speed or Hs value especially where the data refer to multiple UKCS areas or months. By drawing a vertical line from any point on the ‘x’ axis to where it crosses the data point line, then a horizontal line to the ‘y’ axis it is possible to determine the percentage of trials carried out at less than or equal to the chosen percentage of the average maximum wind speed. In respect of Figure 8 that data indicates that approximately 30% of all trials occurred when the wind speed was up to 50% of the average maximum whereas only 10% were conducted when the wind speed was up to 76% of the maximum. Conversely, an alternative representation demonstrates that approximately 2.5% of all rescue craft trials were carried in wind speeds that exceeded 90% of the average maximum. To provide an indication of the number of trials carried out at each 1% exceedence interval Figure 9, presents the results of a count of records at each 1% figure. The chart is overlaid with a logarithmic trend line.

Figure 9 Count of all rescue craft trials carried out at each 1% exceedence of average maximum wind speeds

A similar analysis to that described above was carried out comparing the Hs. The results are presented in Figures 10 and 11 and are composed of all records in dataset ‘A’ (1722 trials) along with the rescue craft trials from dataset ‘B’ (796 trials). Once again the MRD trials were excluded though they are presented separately in Appendix 2, Section 3.1.

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Figure 10 Percentage of all rescue craft trials carried out in percentage of average maximum significant wave height

Figure 11 Count of all rescue craft trials carried out at each 1% exceedence of average maximum significant wave height

On the whole Figures 8 and 10 indicate a steady decline in the number of trials carried out in both worsening wind and Hs conditions although the gradient tends to be steeper up to

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approximately 15% exceedence. This indicates a greater proportion of trials having been conducted under more benign conditions. For explanation, had the graph shown a ‘flatter’ appearance it would have indicated a more even spread of weather conditions. In both Figures 8 and 10 it is important to note that the line terminates above the baseline at 100% indicating that some trials were carried out in conditions that were worse in terms of wind and Hs than the average of the worst conditions that had been recorded. Figures 9 and 11 demonstrate that trials have been conducted across the entire range of wind and Hs exceedences although the trend lines indicate, as is to be expected, the numbers become fewer as the conditions become more severe. However, basing the charts on the whole dataset means it is not possible to determine whether the trials in more severe weather were conducted only by a small group of ERRV, perhaps those fitted with better equipment, or by a wide range of vessels. Figures 8 to 11 present the results of exceedence data comparisons from an overview perspective insofar as all areas of the UKCS and all rescue craft trials have been included as a single data source. To gauge the influence of such factors as the UKCS area and the type of equipment, charts for individual areas and type of equipment are presented in Appendix 2, Section 3.1 for dataset ‘B’ and Appendix 2, Section 3.2 for dataset ‘A’. The detailed charts have been arranged as follows:

Appendix 2, Section 3.1 (based on dataset ‘B’) All rescue craft trials against average maximum wind speeds in all UKCS areas (796 trials) All rescue craft trials against average maximum wind speeds in NNS (303 trials) All rescue craft trials against average maximum wind speeds in CNS (455 trials) All rescue craft trials against average maximum wind speeds in SNS (28 trials) All rescue craft trials against average maximum wind speeds WofS (10 trials) All rescue craft trials against average maximum Hs in all UKCS areas (796 trials) All rescue craft trials against average maximum Hs in NNS (303 trials) All rescue craft trials against average maximum Hs in CNS (455 trials) All rescue craft trials against average maximum Hs in SNS (28 trials) All rescue craft trials against average maximum Hs WofS (10 trials) All MRD trials against average maximum wind speeds in all UKCS areas (715 trials) All MRD trials against average maximum wind speeds in NNS (192 trials) All MRD trials against average maximum wind speeds in CNS (462 trials) All MRD trials against average maximum wind speeds in SNS (39 trials) All MRD trials against average maximum wind speeds WofS (22 trials) All MRD trials against average maximum Hs in all UKCS areas (719 trials) All MRD trials against average maximum Hs in NNS (192 trials) All MRD trials against average maximum Hs in CNS (466 trials) All MRD trials against average maximum Hs in SNS (39 trials) All MRD trials against average maximum Hs WofS (22 trials)

Appendix 2, Section 3.2 (based on dataset ‘A’) All FRC trials against average maximum wind speeds in all UKCS areas (1267 trials) All FRC trials against average maximum wind speeds in NNS (404 trials) All FRC trials against average maximum wind speeds in CNS (748 trials) All FRC trials against average maximum wind speeds in SNS (18 trials) All FRC trials against average maximum wind speeds in IS (67 trials) All FRC trials against average maximum wind speeds WofS (30 trials) All FRC trials against average maximum Hs in all UKCS areas (1294 trials) All FRC trials against average maximum Hs in NNS (389 trials)

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All FRC trials against average maximum Hs in CNS (776 trials) All FRC trials against average maximum Hs in SNS (18 trials) All FRC trials against average maximum Hs in IS (66 trials) All FRC trials against average maximum Hs WofS (45 trials) All DC trials against average maximum wind speeds in all UKCS areas (422 trials) All DC trials against average maximum wind speeds in NNS (208 trials) All DC trials against average maximum wind speeds in CNS (192 trials) All DC trials against average maximum wind speeds in SNS (8 trials) All DC trials against average maximum wind speeds in IS (8 trials) All DC trials against average maximum wind speeds WofS (6 trials) All DC trials against average maximum Hs in all UKCS areas (428 trials) All DC trials against average maximum Hs in NNS (200 trials) All DC trials against average maximum Hs in CNS (206 trials) All DC trials against average maximum Hs in SNS (8 trials) All DC trials against average maximum Hs in IS (8 trials) All DC trials against average maximum Hs WofS (6 trials)

It is apparent from a review of the detailed charts of wind and Hs exceedence data that a number of conclusions can be drawn: Dataset ‘B’ rescue craft data and wind speed

Overall, 76% of dataset ‘B’ rescue craft trials were carried out in less than 50% of the average maximum wind speed. In the NNS the data shows that 3% of trials occurred in greater than 80% of average maximum wind and less than 1% of trials in greater than 90% of maximum wind. 2% of rescue craft trials in the CNS and 14% in the SNS were carried out when the wind speed was greater than 90% of the average maximum. To the WofS all trials were carried out in less than 81% of the average maximum wind.

Dataset ‘B’ rescue craft data and Hs

As with the wind speed, 70% of the rescue craft trials of dataset ‘B’ were carried out in less than 50% of the average maximum Hs, whereas in the NNS and CNS 3% of trials occurred in greater than 90% of maximum Hs. This is particularly noteworthy given the higher Hs in the NNS than in other areas of the UKCS. In the SNS, where the average maximum Hs is less than in other areas, 18% of trials were conducted in greater than 90% of the average maximum. Conversely, to the WofS where the average Hs is greater than other areas only 10% (1 trial) occurred at 90% of maximum Hs.

Dataset ‘B’ MRD data and wind speed

Perhaps as expected, a much larger proportion of MRD trials are carried out in more severe weather. Of dataset ‘B’ 11% of MRD trials were carried out in greater than 90% of the average maximum wind conditions. However, a major difference of the results from the MRD with those of the rescue crafts, is that approximately 11% of trials were carried out in greater than 90% of the average maximum wind in all areas of the UKCS (except WofS where it was 5%) rather than there being a higher percentage in the CNS and SNS and less in the NNS.

Dataset ‘B’ MRD data and Hs

In respect of Hs about 10% of trials occurred in greater than 90% of the average maximum though these tended to have taken place in the CNS and SNS.

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Dataset ‘A’ FRC data and wind speed Results from analysis of dataset ‘A’ are broadly similar to those of dataset ‘B’:

68% of dataset ‘A’ FRC trials were carried out in less than 50% of the average maximum wind speed. In the NNS the data shows that 3% of trials occurred in greater than 80% of average maximum wind and less than 1% of trials in greater than 90% of maximum wind. 4% of FRC trials in the CNS and 1% in the IS were carried out when the wind speed was greater than 90% of the average maximum. In the SNS and to the WofS all FRC trials were carried out in less than 85% of the average maximum wind.

Dataset ‘A’ FRC data and Hs

As with the wind speed, 67% of dataset ‘A’ FRC trials were carried out in less than 50% of the average maximum Hs. More surprisingly, in the NNS 8% of trials and 22% to the WofS occurred in greater than 90% of maximum Hs, whereas other areas of the UKCS where the Hs is generally less, carried out fewer trials in more severe weather conditions. In the SNS, where the average maximum Hs is less than in other areas, 18% of trials were conducted in greater than 90% of the average maximum. Conversely, to the WofS where the average Hs is greater than other areas only 10% (1 trial) occurred at 90% of maximum Hs.

Dataset ‘A’ DC data and wind speed Dataset ‘A’ is smaller (422 trials for wind speed and 438 for Hs) and therefore it becomes less valid to draw conclusions. However, for the whole dataset trials were more evenly spread across the full range of average wind speeds, i.e., 60% of trials were carried out in up to 50% of the maximum average wind speeds and 40% above this figure. Analysis by area demonstrates that in the NNS and WofS there were more DC trials in lesser wind conditions with the trials in more severe weather being carried out only in the CNS. In respect of Hs DC trials were only carried out in greater than 90% of the average maximum in the NNS and CNS whereas in all other areas no trials were carried out under such conditions. 4.2.4 Target recovery times A feature of dataset ‘B’ is the recording of the time taken for exercises, whether they were carried out by one or more rescue craft or by MRD, the number of ‘targets’ (presumably mannequins) recovered and the range from the ERRV. Using this information an analysis was undertaken to determine whether any broad conclusions could be drawn to support the widely held belief that recovery takes longer in worsening weather and the greater the distance from the ERRV. Furthermore, to investigate whether a review of recovery times could be used as a basis for predicting how long survivor might take in more severe conditions. For the sake of data presentation the parameters considered for the recovery times are the Hs and distance from the installation. Although the rescue craft trials contained a mixture of data in which either 1, 2 or 3 craft had been used this was rationalised to remove those records where more than 1 craft was involved. This was done to provide a like for like basis for analysis and resulted in a total of 171 records being deleted (170 records involving 2 rescue craft and 1 trial using 3 craft). In total 632 records were subjected to this analysis. From each trial where the number of targets recovered, distance from the ERRV (binned into 1 nautical mile ranges) and Hs (binned into 1 of 4 groups) were the same, an average was taken of the total times recorded in dataset ‘B’. This approach was used regardless of whether constant

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tension equipment was fitted or not. From the ‘time taken’ averages a chart was produced illustrating, for a given number of targets at a given range and given Hs, how long recovery may take. Obviously, because the chart indicates ‘average times’, it is reasonable to argue that on some vessels, perhaps depending on the levels of equipment and crew training, the times could be considerably less. Moreover, because some of the data points on the charts are the average times from a small number of the trials, the accuracy and confidence that one may wish to assume could be quite low, i.e., small sample groups of three or less trials may be statistically invalid. Under these circumstances it is inevitable that a large margin of error could exist. To assist in interpretation of the performance charts the sample size for each data point is tabulated, as is the average recovery time for each data point. By way of explanation it should be noted that where there were no target recovery trials at a given range and Hs then the line joining data points becomes discontinuous, as is the case for Hs bin = 2 (1.0m - <2.0m) between range bin 5 and 7 in Figure 12 because there were no trials carried out at range bin 6. In other cases there may be a single data point on a chart as for Hs bin 2 at range bin 9 on Figure 13 because no trials were conducted at either range bin 8 or 10 at that Hs. Inspection of the data indicated that the majority of rescue craft trials involved the recovery of 1 target whereas most trials of MRD recovered 20 targets and therefore Figures 12 and 13 graphically present the results of the average recovery times for these scenarios. Other charts and tables are presented in Appendix 2, Section 4.1 (for rescue craft) and Appendix 2, Section 4.2 for (MRD). Although the trials have been carried out in ‘controlled circumstances’ to some extent insofar as they were reportedly independently witnessed and verified, there will inevitably be a number of variables that may lead to erroneous assumptions being drawn. Caution should be exercised in reading too fine a level of detail in individual charts though the trends may be sufficiently accurate in broad terms.

Table 6 Number of rescue craft trials involving one target

Number of rescue craft recovery trials involving 1 target (total = 506 trials) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 72 7 5 6 4 3 2 0 0 0 2 168 30 24 14 15 0 2 2 0 0 3 102 20 6 9 9 3 0 0 0 0 4 3 0 0 0 0 0 0 0 0 0

Table 7 Average times of rescue craft trials involving one target

Average rescue craft recovery times for 1 target (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10

27

1 6.0 8.2 11.8 14.6 19.3 20.5 27.0 - - - 2 6.3 9.7 11.8 16.1 20.7 - 15.0 37.0 - - 3 6.0 9.6 11.6 15.7 19.7 18.0 - - - - 4 5.0 - - - - - - - - -

Figure 12 Average time to recover 1 target by rescue craft at various ranges

Table 8 Number of MRD trials involving twenty targets

Number of MRD trials involving 20 targets (total = 398 trials) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 19 15 11 12 5 0 5 0 0 0 2 51 31 18 20 12 7 3 0 4 0 3 57 34 23 19 13 3 9 7 9 0 4 8 3 0 0 0 0 0 0 0 0

Table 9 Average times of MRD trials involving twenty targets

Average MRD times for 20 targets (mins.)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 49.6 49.6 60.2 53.6 57.0 - 65.6 - - - 2 58.1 54.3 50.5 64.7 69.6 54.1 65.0 - 74.0 - 3 63.5 68.9 65.6 64.3 73.6 57.5 79.5 89.1 96.0 - 4 46.6 43.5 - - - - - - - -

0

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40

1 2 3 4 5 6 7 8 9 10

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Ave

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Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

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28

Figure 13 Average time to recover 20 targets by MRD at various ranges It is fair to assume that rescue times could be almost halved if there are two rescue craft in use provided they are properly organised and don’t both return to the mother vessel at the same time for survivor transfer also that there are sufficient crew on board the mother vessel to handle both previously rescued survivors and those transferred later, i.e., that everyone isn’t involved in survivor care and that some are available for survivor transfer. However, this assumption is based on the exclusion of survivor location and dispersal; if rescue craft have difficulty in first finding survivors before recovering them then the times can be extended considerably. Similarly, if survivors are spread over a large area, albeit at approximately the same range recovery times will also be increased. Particularly striking in Figure 12 is the apparently limited effect that increasing Hs has on rescue craft performance up to 5 miles from the mother vessel. As is to be expected the time taken to recover a single target increases almost linearly with increasing distance but the average time is broadly similar regardless of sea state up to 3.5m Hs. Beyond 5 miles distance from the mother vessel the average single target recovery times become more uncertain though it is highly likely the results were affected by the small sample sizes on which they were based. The results of MRD trials in Figure 13 are more difficult to explain as they appear to show that while worsening sea states tend to extend the target recovery process, the distance of targets from the rescue vessel appears to be less of a factor, certainly for trials conducted up to 5 miles distant. This may be because when using MRD the ERRV only needs to steam the distance between it’s alarm point position and the targets once whereas for a rescue craft recovery an ‘out and back’ journey is required albeit, shorter on the return leg as the ERRV is likely to be steaming towards the rescue craft. What is apparent from even a cursory review of the detailed performance charts in Appendix 2, Section 4 is the somewhat perverse information they contain; on some charts the average time for target recovery reduces even though either the survivors are further away from the ERRV, or the weather conditions are more severe, or both. When adopting conventional wisdom both of these factors would normally increase recovery time although the results presented in Figures 12

0

20

40

60

80

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120

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Ave

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Hs = 1.0m - <2.0m

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29

and 13 demonstrate that such wisdom is perhaps not as clear cut as previously believed. In reality the results are a somewhat ‘blunt instrument’ as it is likely that the level and type of equipment may have an impact on performance. However, it is probably more likely that crew competence will have an even greater effect on performance. Crews that frequently practice with rescue craft or mechanical recovery devices in well thought out and meaningful exercises are more likely to become very proficient in their use than those where trials are conducted in less realistic conditions. Furthermore, a preponderance of exercises in benign weather conditions will do little to engender trust among the participants that a) the system will work if called upon in more severe weather and, b) their colleagues will be able to act professionally and efficiently if unforeseen circumstances arise. Overall, what the detailed charts indicate is that the results could be used as a guide to performance under certain conditions rather than as an absolute. As many of the trials have been carried out by a small percentage of the vessels (many only have a few trials to their name) it is possible the figures could have been skewed if the vessels that have carried out the majority of the trials are either very efficient or poor. If they are particularly efficient (which may well be the case if they have had so much experience and training compared to some others), then their times for recovery of survivors will artificially lower the average of all trials. Conversely, if they are poor then the average time will be driven upwards. Taken as a complete set the performance charts may be useful in providing an indicative measure of what is possible offshore, always being mindful that some charts are based on somewhat scanty information and therefore the potential margin for error is likely to increase. In and of themselves the results do not take into account many of the factors that can influence the speed and success of a survivor recovery operation, factors such as wave steepness, modernity and fitness for purpose of equipment and crew training and competence. Perhaps more importantly, the results also highlight the difficulty of predicting what future performance may be in more severe conditions. 4.2.5 ‘Exemplar’ performance It is very difficult, and probably not valid, to make trial by trial comparisons between different vessels of, for instance, the time taken to carry out similar target recovery exercises or the prevailing conditions when trials were conducted. Analysing comparative performance between ERRV would not be particularly helpful as the results would be based on data comprising only some of the many variables that affect the speed and success of a trial. While factors such as Hs, wind, tide, weather, number of casualties, distance to casualties and equipment type, etc., are recorded and could be compared, there are others such as crew familiarity with the equipment, the vessel’s training regime and the operators management philosophy that are not recorded but which could have a marked effect on the success of a trial. While the notion of producing league tables to indicate enhanced performance was dismissed, it is apparent from reviewing datasets ‘A’ and ‘B’ that wide disparity exists between different ERRV nonetheless. Some ERRV consistently trial in more severe conditions than others and it is felt to be beneficial to highlight average wind and Hs conditions when trials were consistently carried out in adverse weather. Initially all rescue craft trials of datasets ‘A’ and ‘B’ were combined, a total of 2500 records, and compared with exceedence data from OTO01030; this was accomplished in the same manner as described in sub-sections 3.2.3 and 4.2.3. The results of incorporating exceedence data were then grouped according to the unique but anonymising ERRV identifier. As previously presented in Tables 4 and 5 there is a wide range in the number of trials carried out

30

by individual ERRVs and therefore to avoid potentially skewing of the results because of some vessels having carried out only a small number of trials, it was necessary to set a threshold to disregard ERRV about which little data was available. The threshold was set at a minimum of 20 trials and yielded 42 ERRV that had exceeded this number. Data from the 42 ERRV to be included in this analysis were then arranged so that an average was deduced from the percentage wind exceedence of each trial they had carried out. The process was then repeated to indicate the average percentage Hs exceedence. From this approach a single vessel was identified that had consistently carried out trials in more adverse conditions. All records from datasets ‘A’ and ‘B’ from the ERRV identified through this procedure were then extracted to produce Figures 14 and 15, overleaf. Figure 14 indicates that on the particular ERRV from which the records were drawn, trials were carried out across the full range of conditions experienced in the relevant UKCS area and approximately 15% were carried out in greater than 90% of the average maximum Hs conditions. Figure 15 presents the same information from a different perspective insofar as the majority of trials occurred in Hs conditions of greater than 80% of the average maximum.

NB: Chart based on 46 trials Figure 14 Percentage of rescue craft trials carried out on ERRV in

percentage of average maximum significant wave height

0%

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Percentage of average maximum significant wave height

Perc

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Figure 15 Count of rescue craft trials carried out on ERRV at each 1% exceedence of average maximum significant wave height

In overview the results presented in Figures 14 and 15 confirm that some vessels are able to achieve high levels of competency in moderate and severe weather conditions up to and including the maximum to be expected in the area of operation for the relevant season. On a cautionary note the time of year should also be taken into account as the data presented above refers only to trials conducted during the summer months when wind and Hs tend to be less severe than at other times of the year. Working with a limited dataset highlights the shortcomings of extrapolation of trials data to all seasons and all areas but, nonetheless, bodes well for demonstrating that a good prospect of success in rescue and recovery operations via rescue craft can be expected. Having concluded that some vessels, and the ERRV singled out above is by no means unique, can achieve high levels of performance it is incumbent on all vessels to demonstrate similar levels of performance during their drills.

0

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0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Percentage of average maximum significant wave height

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V

5 SUMMARY OF RESULTS During the course of this research a number of factors affecting the conduct of rescue craft trials on the UKCS have manifested themselves. Although many of the important factors that became apparent are presented in some detail at various points in the report it is felt worthwhile that they be reiterated here:

Figure 2 (sub-section 4.2.1) shows a comparison of the month when trials were carried out compared to their number and demonstrates a good correlation with the length of daylight. There are several possible explanations for more trials having been carried out during some months:

(i) Crews possibly took advantage of longer days by carrying out more trials per day than during winter months; (ii) The majority of dataset ‘A’ trials were carried out during the summer months of 2005 and, because of the size of this dataset compared to the number of records in dataset ‘B’, the results have been somewhat skewed; (iii) ERRV crews may be more inclined to carry out rescue craft trials when the prevailing wind and Hs conditions are more favourable, i.e., during summer months.

In an ideal world where improvements in rescue equipment and crew training are an on-going process it is fair to hope there will be a consistent and continual improvement in the outcomes from rescue trials. While there may be an expectation of enhanced rescue and recovery capability based on anecdotal evidence and the implementation of changes to the training regime more recently compared to several years ago, the data presented in Figure 3 does not completely bear this out. In particular, when comparing the date of trials and the prevailing Hs it is apparent that just as many trials were recently carried out in lesser sea states than was the case when data were first collected. To some extent Figure 3 can be misleading in this respect because the data covered only a short period of predominantly summer months when it can be argued that more benign conditions are likely to have been experienced.

Notwithstanding the assertion that the majority of trials were carried out in lesser wind and sea states, the data contained examples of trials having been consistently and successfully carried out on several ERRVs in relatively severe weather conditions. Figure 14 (sub-section 4.2.5) highlights the activities of one such vessel and perhaps could be used as a benchmark for others to strive towards.

One of the factors that appears to be of note in determining the number of trials carried out by individual vessels, and to a lesser extent the severity of wind and Hs when the trials were conducted, is the former history of the vessel before conversion to an ERRV. By extension the level of vessel equipment is also important and when comparing the breakdown of the UKCS ERRV fleet with the number of trials carried out by each vessel type (Figures 5 and 6), it indicates the benefit in using constant tension equipment for rescue craft recovery. Crews appear to be more motivated and undertake a larger proportion of trials than the number of such vessels suggest.

On the face of it the dataset, large though it may be, does not appear to lend itself to extrapolation for determining likely rescue craft performance in conditions beyond those actually experienced. What is clear in this respect is that many factors over and above those contained in the dataset need to be considered as well as the need for some form of external validation to ensure confidence in the results.

•

•

•

•

•

33

6 DISCUSSION Notwithstanding the possibility for erroneous data based on small sample sizes, the charts in Section 4.2.4 and Appendix 2, Section 4 do give a guide to the sort of performance that ought to be expected. It is important to note, however, that because they are an average some ERRV may perform better and some worse based on several factors such as equipment type and crew competence. Obviously a larger dataset, particularly of trials carried out in greater sea states, would be of benefit to enhance the accuracy of the results. What is less clear is whether it is valid to make predictions of performance in severe conditions, i.e., where the Hs is greater than 5.5m, based on extrapolations of existing data. On balance it is believed that predicting rescue craft performance is an extremely complex process and one that can not be adequately addressed through merely extrapolating the results of trials in less severe conditions. Unless the many variables that go to make up a successful trial are taken into account and properly considered it is suggested that the results of such extrapolation may be difficult to justify. Rather than only the extrapolation of trials data it may be that mathematical modelling also has a part to play. Data collected from full scale trials under rigidly controlled conditions, or from tank testing of scale models, may be used as a basis for finite element analysis of different makes and models of craft. However, while it is noted that the results of such analysis may give an indication of the theoretical maximum conditions under which a rescue craft rescue could be effected, it does little to address any of the human factors issues. For this there probably will need to be some input from actual trials, possibly trials carried out using benchmark conditions to feed into a mathematical model, to ascertain the ceiling level of performance for a particular craft/crew combination. The trials data used for this study proved to be an extremely valuable resource. However, it is suggested that those in charge of data gathering may wish to consider slightly modifying their data collection protocol to further add value. In particular some information on the time of day when trials are carried out could be beneficial to any further analysis.

34

APPENDIX 1 AVERAGE PERCENTAGE EXCEEDENCE DATA FOR AREAS OF UKCS

Northern North SeaMean Wind Speed – Percentage Exceedence Distribution

m/s knots BF Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 0 0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.3 1 1 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.002 100.00 100.00 100.00 99.98 99.96 99.98 99.97 99.99 99.99 99.99 100.00 100.00 99.993 100.00 100.00 100.00 99.96 99.93 99.97 99.93 99.98 99.98 99.99 99.99 99.99 99.97

1.6 4 2 100.00 99.99 100.00 99.94 99.89 99.95 99.90 99.96 99.96 99.98 99.99 99.99 99.965 99.41 99.14 99.33 98.68 96.81 97.28 96.72 96.83 98.69 98.74 99.27 99.17 98.336 98.83 98.28 98.67 97.42 93.73 94.61 93.55 93.69 97.42 97.50 98.54 98.35 96.70

3.4 7 3 98.25 97.43 98.01 96.17 90.66 91.94 90.37 90.56 96.15 96.27 97.82 97.54 95.078 96.81 95.25 96.04 92.85 85.47 86.81 84.62 85.47 92.75 93.51 95.79 95.64 91.729 95.38 93.07 94.06 89.54 80.29 81.69 78.87 80.37 89.35 90.76 93.77 93.74 88.3710 93.94 90.89 92.09 86.22 75.10 76.56 73.12 75.28 85.94 88.01 91.74 91.85 85.01

5.5 11 4 92.51 88.71 90.12 82.91 69.92 71.43 67.38 70.19 82.54 85.26 89.71 89.95 81.6612 90.27 86.17 87.47 78.75 65.29 66.26 61.86 65.30 78.56 82.13 86.91 87.64 77.9913 88.04 83.63 84.82 74.59 60.67 61.09 56.35 60.42 74.58 79.00 84.11 85.32 74.3214 85.80 81.09 82.17 70.43 56.04 55.92 50.84 55.53 70.60 75.87 81.31 83.01 70.6515 83.57 78.55 79.52 66.27 51.42 50.74 45.33 50.65 66.62 72.74 78.51 80.70 66.9816 81.33 76.02 76.88 62.11 46.80 45.57 39.82 45.76 62.63 69.61 75.71 78.39 63.31

8 17 5 79.10 73.48 74.23 57.95 42.17 40.40 34.31 40.88 58.65 66.48 72.91 76.07 59.6418 75.17 69.09 69.58 52.30 37.22 34.83 29.49 35.78 53.13 61.34 68.28 71.64 54.7419 71.23 64.71 64.94 46.65 32.27 29.26 24.67 30.68 47.61 56.20 63.64 67.22 49.8420 67.30 60.32 60.29 41.00 27.32 23.69 19.86 25.58 42.09 51.06 59.01 62.79 44.9421 63.37 55.94 55.64 35.35 22.37 18.11 15.04 20.48 36.56 45.93 54.37 58.36 40.05

10.8 22 6 59.44 51.55 51.00 29.70 17.42 12.54 10.23 15.38 31.04 40.79 49.74 53.93 35.1523 55.42 47.76 46.68 26.38 15.00 10.80 8.73 13.28 27.85 37.02 45.50 49.62 31.9324 51.41 43.98 42.36 23.07 12.57 9.06 7.22 11.18 24.67 33.26 41.27 45.31 28.7025 47.39 40.19 38.04 19.75 10.14 7.32 5.72 9.08 21.48 29.49 37.04 41.00 25.4826 43.38 36.40 33.73 16.44 7.71 5.58 4.22 6.97 18.29 25.73 32.81 36.69 22.2627 39.37 32.61 29.41 13.12 5.29 3.83 2.72 4.87 15.10 21.96 28.58 32.37 19.04

13.9 28 7 35.35 28.83 25.09 9.81 2.86 2.09 1.21 2.77 11.91 18.20 24.35 28.06 15.8229 31.67 25.75 21.98 8.48 2.44 1.77 1.03 2.34 10.48 16.11 21.55 25.02 14.0030 27.99 22.67 18.88 7.16 2.02 1.45 0.84 1.92 9.06 14.02 18.75 21.97 12.1831 24.31 19.59 15.77 5.83 1.60 1.12 0.65 1.49 7.63 11.93 15.94 18.92 10.3632 20.63 16.51 12.66 4.51 1.18 0.80 0.46 1.07 6.20 9.85 13.14 15.88 8.5433 16.94 13.43 9.55 3.18 0.75 0.48 0.27 0.64 4.77 7.76 10.34 12.83 6.72

17.2 34 8 13.26 10.35 6.45 1.86 0.33 0.15 0.08 0.22 3.34 5.67 7.54 9.78 4.9035 11.74 9.09 5.64 1.62 0.29 0.13 0.07 0.19 2.97 5.04 6.65 8.80 4.3336 10.22 7.84 4.84 1.38 0.25 0.11 0.06 0.16 2.60 4.40 5.75 7.81 3.7737 8.70 6.58 4.03 1.14 0.21 0.09 0.05 0.12 2.23 3.77 4.86 6.82 3.2038 7.18 5.32 3.23 0.90 0.17 0.07 0.03 0.09 1.85 3.14 3.97 5.83 2.6439 5.66 4.06 2.43 0.66 0.13 0.04 0.02 0.06 1.48 2.51 3.08 4.85 2.0740 4.14 2.80 1.62 0.42 0.08 0.02 0.01 0.03 1.11 1.87 2.18 3.86 1.51

20.8 41 9 2.63 1.55 0.82 0.18 0.04 0.00 0.00 0.00 0.74 1.24 1.29 2.87 0.9542 2.29 1.34 0.71 0.16 0.04 0.00 0.00 0.00 0.64 1.10 1.13 2.53 0.8343 1.96 1.13 0.61 0.13 0.03 0.00 0.00 0.00 0.55 0.97 0.96 2.19 0.7144 1.62 0.93 0.50 0.11 0.02 0.00 0.00 0.00 0.46 0.83 0.80 1.85 0.5945 1.29 0.72 0.40 0.09 0.02 0.00 0.00 0.00 0.37 0.69 0.63 1.50 0.4846 0.96 0.52 0.30 0.06 0.01 0.00 0.00 0.00 0.27 0.56 0.47 1.16 0.3647 0.62 0.31 0.19 0.04 0.01 0.00 0.00 0.00 0.18 0.42 0.31 0.82 0.24

24.5 48 10 0.29 0.11 0.09 0.01 0.00 0.00 0.00 0.00 0.09 0.28 0.14 0.48 0.1349 0.26 0.10 0.08 0.01 0.00 0.00 0.00 0.00 0.08 0.25 0.13 0.43 0.1150 0.23 0.09 0.07 0.01 0.00 0.00 0.00 0.00 0.07 0.21 0.11 0.37 0.1051 0.20 0.08 0.06 0.01 0.00 0.00 0.00 0.00 0.06 0.18 0.09 0.32 0.0852 0.17 0.07 0.04 0.01 0.00 0.00 0.00 0.00 0.05 0.14 0.07 0.27 0.0753 0.14 0.06 0.03 0.01 0.00 0.00 0.00 0.00 0.04 0.11 0.06 0.22 0.0654 0.10 0.05 0.02 0.00 0.00 0.00 0.00 0.00 0.03 0.07 0.04 0.16 0.0455 0.07 0.04 0.01 0.00 0.00 0.00 0.00 0.00 0.02 0.04 0.02 0.11 0.03

28.5 56 11 0.04 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.06 0.0257 0.04 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.05 0.0158 0.03 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.04 0.0159 0.03 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.04 0.0160 0.03 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.03 0.0161 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.0162 0.02 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.0063 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00

32.7 64 12 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0012.05 11.19 10.96 9.02 7.55 7.37 7.01 7.45 9.22 10.08 10.90 11.39 -Mean WS

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36

Northern North SeaSignificant Wave Height – Percentage Exceedence Distribution

m Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.5 99.94 99.96 100.00 99.68 97.82 97.11 96.76 98.75 99.66 99.94 99.94 99.75 99.101 98.35 95.99 97.39 90.96 70.71 71.63 59.82 68.68 86.84 94.19 96.55 97.22 85.60

1.5 93.27 86.01 89.75 68.47 43.20 35.95 29.88 38.36 63.29 76.65 85.21 89.96 66.552 82.66 73.05 75.64 47.26 24.68 15.66 13.14 19.69 42.53 57.02 68.84 77.78 49.71

2.5 69.64 57.46 59.74 30.69 13.91 7.12 5.18 9.23 28.59 39.98 52.34 63.41 36.353 56.38 44.74 44.88 18.40 6.86 3.18 1.79 3.75 19.22 28.46 38.36 48.99 26.18

3.5 42.65 34.42 31.55 10.91 3.74 1.36 0.63 1.62 12.49 20.36 27.41 36.05 18.534 32.00 25.91 21.03 6.22 2.15 0.44 0.27 0.73 8.06 14.46 18.93 25.57 12.93

4.5 23.38 19.20 13.42 3.79 1.06 0.13 0.10 0.27 5.24 10.12 12.55 17.88 8.895 16.49 13.19 8.10 2.37 0.56 0.04 0.04 0.11 3.48 6.81 8.39 12.63 5.99

5.5 11.24 8.81 5.09 1.52 0.28 0.01 0.00 0.05 2.51 4.57 5.29 9.01 4.016 7.66 5.45 3.05 1.02 0.10 0.00 0.00 0.02 1.83 3.06 3.44 6.62 2.68

6.5 5.72 3.72 1.96 0.81 0.06 0.00 0.00 0.01 1.36 2.23 2.66 5.29 1.987 4.80 2.72 1.54 0.71 0.04 0.00 0.00 0.00 1.23 1.78 2.24 4.38 1.62

7.5 5.07 2.81 2.08 0.72 0.04 0.00 0.00 0.00 1.27 1.76 2.20 3.98 1.668 3.76 1.89 1.59 0.47 0.02 0.00 0.00 0.00 1.07 1.44 1.70 2.89 1.23

8.5 3.57 1.98 1.54 0.42 0.00 0.00 0.00 0.00 0.94 1.20 1.40 2.14 1.1011.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0012 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

12.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0013 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

13.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0015.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Mean HSIG 3.50 3.12 3.03 2.17 1.58 1.41 1.28 1.46 2.14 2.57 2.87 3.27 -

37

Central North SeaMean Wind Speed – Average Percentage Exceedence Distribution

m/s knots BF Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 0 0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.3 1 1 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.002 100.00 99.99 100.00 100.00 99.98 99.94 99.98 99.99 100.00 100.00 100.00 100.00 99.993 100.00 99.99 100.00 99.99 99.97 99.89 99.95 99.97 99.99 100.00 99.99 99.99 99.98

1.6 4 2 100.00 99.98 100.00 99.99 99.95 99.83 99.93 99.96 99.99 99.99 99.99 99.99 99.965 99.05 98.85 99.23 98.58 96.44 96.02 96.55 97.13 98.86 99.13 99.37 99.27 98.206 98.10 97.72 98.45 97.17 92.93 92.21 93.17 94.31 97.73 98.26 98.74 98.54 96.43

3.4 7 3 97.15 96.59 97.68 95.76 89.43 88.41 89.79 91.48 96.60 97.39 98.12 97.82 94.678 95.13 94.03 95.62 92.08 83.31 82.50 83.02 86.49 92.60 94.39 95.84 95.24 90.839 93.12 91.48 93.57 88.39 77.19 76.59 76.25 81.49 88.60 91.39 93.55 92.67 86.9910 91.10 88.92 91.51 84.70 71.08 70.68 69.48 76.49 84.61 88.39 91.27 90.09 83.15

5.5 11 4 89.09 86.37 89.45 81.01 64.96 64.77 62.71 71.50 80.61 85.39 88.98 87.51 79.3112 86.61 83.41 86.29 76.41 59.88 59.22 57.25 65.83 76.22 81.04 85.91 84.39 75.1513 84.13 80.46 83.12 71.82 54.79 53.68 51.79 60.17 71.83 76.70 82.85 81.27 70.9914 81.65 77.50 79.95 67.22 49.70 48.13 46.34 54.51 67.44 72.36 79.78 78.15 66.8215 79.17 74.55 76.79 62.62 44.62 42.58 40.88 48.85 63.05 68.02 76.71 75.03 62.6616 76.69 71.59 73.62 58.02 39.53 37.04 35.42 43.18 58.66 63.68 73.65 71.91 58.50

8 17 5 74.21 68.64 70.45 53.43 34.45 31.49 29.96 37.52 54.27 59.33 70.58 68.79 54.3418 69.90 64.15 65.45 47.66 29.67 26.81 25.47 32.55 48.82 53.35 65.67 64.09 49.3719 65.60 59.67 60.45 41.88 24.90 22.13 20.98 27.59 43.37 47.37 60.76 59.39 44.4120 61.30 55.19 55.45 36.11 20.12 17.46 16.49 22.62 37.91 41.38 55.85 54.69 39.4521 57.00 50.70 50.45 30.34 15.35 12.78 12.01 17.65 32.46 35.40 50.94 49.99 34.49

10.8 22 6 52.70 46.22 45.45 24.57 10.58 8.10 7.52 12.68 27.01 29.41 46.03 45.29 29.5323 48.64 42.41 41.30 21.58 8.96 6.89 6.40 10.93 24.04 26.13 41.49 41.40 26.5924 44.58 38.60 37.15 18.60 7.35 5.68 5.28 9.17 21.07 22.84 36.95 37.50 23.6525 40.51 34.79 33.00 15.61 5.74 4.47 4.16 7.42 18.11 19.55 32.41 33.60 20.7026 36.45 30.98 28.84 12.62 4.13 3.26 3.04 5.66 15.14 16.26 27.87 29.70 17.7627 32.39 27.16 24.69 9.64 2.52 2.05 1.91 3.91 12.17 12.98 23.33 25.81 14.82

13.9 28 7 28.33 23.35 20.54 6.65 0.91 0.84 0.79 2.15 9.21 9.69 18.80 21.91 11.8729 25.38 20.81 17.91 5.71 0.76 0.71 0.66 1.81 8.03 8.50 16.38 19.38 10.4530 22.44 18.26 15.28 4.77 0.61 0.57 0.53 1.46 6.86 7.32 13.96 16.85 9.0331 19.50 15.71 12.65 3.83 0.46 0.43 0.40 1.11 5.69 6.14 11.54 14.32 7.6132 16.55 13.17 10.03 2.89 0.31 0.30 0.27 0.77 4.52 4.95 9.12 11.79 6.1933 13.61 10.62 7.40 1.95 0.15 0.16 0.14 0.42 3.34 3.77 6.70 9.26 4.77

17.2 34 8 10.67 8.07 4.77 1.01 0.00 0.02 0.01 0.07 2.17 2.59 4.28 6.73 3.3535 9.43 7.09 4.12 0.87 0.00 0.02 0.01 0.06 1.91 2.32 3.76 5.95 2.9436 8.19 6.12 3.48 0.73 0.00 0.02 0.01 0.05 1.65 2.05 3.24 5.17 2.5437 6.95 5.14 2.84 0.59 0.00 0.01 0.01 0.04 1.38 1.77 2.71 4.39 2.1438 5.72 4.16 2.20 0.45 0.00 0.01 0.00 0.03 1.12 1.50 2.19 3.61 1.7439 4.48 3.18 1.56 0.31 0.00 0.01 0.00 0.02 0.86 1.23 1.67 2.83 1.3440 3.24 2.20 0.92 0.17 0.00 0.00 0.00 0.01 0.59 0.96 1.14 2.05 0.94

20.8 41 9 2.01 1.23 0.27 0.03 0.00 0.00 0.00 0.00 0.33 0.69 0.62 1.27 0.5342 1.74 1.07 0.23 0.02 0.00 0.00 0.00 0.00 0.28 0.61 0.54 1.09 0.4643 1.47 0.91 0.20 0.02 0.00 0.00 0.00 0.00 0.24 0.53 0.46 0.92 0.3944 1.21 0.75 0.16 0.02 0.00 0.00 0.00 0.00 0.19 0.45 0.38 0.75 0.3245 0.94 0.59 0.12 0.01 0.00 0.00 0.00 0.00 0.15 0.37 0.30 0.58 0.2546 0.67 0.44 0.08 0.01 0.00 0.00 0.00 0.00 0.10 0.29 0.22 0.41 0.1847 0.41 0.28 0.04 0.00 0.00 0.00 0.00 0.00 0.05 0.20 0.14 0.24 0.11

24.5 48 10 0.14 0.12 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.12 0.06 0.07 0.0449 0.12 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.11 0.05 0.06 0.0450 0.11 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.09 0.04 0.05 0.0351 0.09 0.08 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.08 0.03 0.04 0.0352 0.07 0.07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.03 0.03 0.0253 0.05 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.02 0.02 0.0254 0.04 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.01 0.02 0.0155 0.02 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.01 0.01 0.01

28.5 56 11 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0057 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0058 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0059 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0060 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0061 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0062 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0063 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

32.7 64 12 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0011.25 10.57 10.45 8.57 6.94 6.75 6.68 7.31 8.79 9.18 10.40 10.51 -Mean WS

Central North SeaSignificant Wave Height – Average Percentage Exceedence Distribution

m Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year

0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.000.5 99.10 99.65 99.74 97.87 92.61 89.42 89.07 92.76 96.86 99.40 99.64 99.18 96.251 91.20 90.31 91.49 79.45 59.47 55.89 49.62 58.14 76.04 85.36 90.18 88.72 76.22

1.5 78.30 72.16 73.32 53.19 32.93 26.52 22.60 30.22 50.78 60.80 70.43 74.15 53.682 62.02 53.80 54.53 31.96 16.57 10.98 9.97 14.77 31.57 39.72 51.64 58.03 36.21

2.5 45.85 39.93 38.23 19.54 7.13 4.84 4.19 7.45 19.45 24.76 36.76 42.93 24.183 33.11 28.56 25.51 11.61 2.69 1.93 1.78 3.50 11.80 15.22 24.77 30.27 15.83

3.5 23.53 20.37 16.61 7.00 1.04 0.64 0.76 1.59 7.17 9.27 15.50 20.93 10.324 16.03 14.29 10.14 4.24 0.22 0.22 0.21 0.68 4.31 5.76 9.15 14.00 6.57

4.5 10.71 9.54 5.71 2.59 0.06 0.06 0.02 0.22 2.73 3.78 5.06 9.08 4.105 8.07 7.41 2.98 1.72 0.04 0.01 0.00 0.01 1.85 2.64 3.58 6.27 2.86

5.5 5.76 5.21 1.45 1.09 0.03 0.00 0.00 0.00 1.46 1.95 2.49 4.48 1.986 4.45 3.83 0.65 0.82 0.02 0.00 0.00 0.00 1.18 1.43 1.91 4.12 1.52

6.5 3.45 3.05 0.28 0.66 0.03 0.00 0.00 0.00 1.06 1.22 1.57 3.55 1.237.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.008.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.009.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

10.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0011.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Mean HSIG 2.58 2.42 2.29 1.74 1.25 1.14 1.08 1.23 1.71 1.95 2.24 2.46 -

38

Southern North SeaMean Wind Speed – Average Percentage Exceedence Distribution

m/s knots BF Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 0 0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.3 1 1 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.002 100.00 99.99 100.00 99.98 99.94 99.87 99.93 99.96 99.99 100.00 99.99 99.99 99.973 99.99 99.98 99.99 99.95 99.88 99.74 99.87 99.91 99.98 99.99 99.98 99.99 99.94

1.6 4 2 99.99 99.98 99.99 99.93 99.82 99.62 99.80 99.87 99.97 99.99 99.97 99.98 99.915 98.64 98.30 98.58 98.01 95.74 95.32 95.59 96.77 98.05 98.58 99.08 98.89 97.626 97.29 96.62 97.18 96.09 91.67 91.03 91.38 93.66 96.13 97.17 98.20 97.80 95.34

3.4 7 3 95.95 94.94 95.78 94.17 87.60 86.74 87.17 90.56 94.22 95.76 97.31 96.71 93.068 93.20 91.60 92.76 89.71 81.03 79.76 80.28 84.16 89.52 92.48 94.60 93.28 88.519 90.45 88.25 89.75 85.25 74.46 72.79 73.38 77.76 84.83 89.21 91.90 89.85 83.9610 87.71 84.90 86.73 80.80 67.89 65.82 66.49 71.36 80.14 85.93 89.19 86.42 79.41

5.5 11 4 84.96 81.55 83.71 76.34 61.32 58.84 59.60 64.96 75.44 82.66 86.49 83.00 74.8612 81.32 77.47 79.61 70.82 55.88 53.17 53.66 59.32 70.82 77.98 82.85 79.62 70.1613 77.67 73.38 75.50 65.31 50.43 47.50 47.72 53.68 66.20 73.31 79.21 76.23 65.4614 74.02 69.30 71.40 59.80 44.99 41.82 41.78 48.05 61.57 68.64 75.57 72.85 60.7615 70.37 65.21 67.29 54.28 39.54 36.15 35.84 42.41 56.95 63.97 71.93 69.47 56.0616 66.73 61.13 63.18 48.77 34.10 30.48 29.90 36.77 52.33 59.30 68.29 66.09 51.36

8 17 5 63.08 57.04 59.08 43.26 28.65 24.80 23.96 31.13 47.70 54.63 64.65 62.71 46.6618 58.20 51.96 53.29 37.78 24.33 20.69 19.96 26.94 42.19 48.71 59.34 58.19 41.7419 53.33 46.88 47.51 32.31 20.00 16.59 15.96 22.76 36.68 42.79 54.02 53.66 36.8220 48.45 41.80 41.72 26.84 15.67 12.48 11.96 18.57 31.17 36.87 48.70 49.14 31.8921 43.57 36.72 35.94 21.36 11.35 8.37 7.96 14.38 25.66 30.95 43.39 44.62 26.97

10.8 22 6 38.70 31.64 30.16 15.89 7.02 4.27 3.96 10.19 20.15 25.03 38.07 40.10 22.0523 35.22 28.42 26.72 13.81 5.90 3.60 3.34 8.74 17.60 21.94 33.99 36.30 19.5924 31.74 25.21 23.28 11.74 4.79 2.92 2.72 7.29 15.05 18.85 29.91 32.51 17.1325 28.26 21.99 19.84 9.66 3.67 2.25 2.10 5.84 12.50 15.76 25.83 28.72 14.6726 24.78 18.78 16.40 7.58 2.55 1.58 1.48 4.39 9.95 12.67 21.75 24.92 12.2127 21.30 15.56 12.97 5.51 1.44 0.91 0.86 2.94 7.40 9.58 17.67 21.13 9.75

13.9 28 7 17.82 12.35 9.53 3.43 0.32 0.24 0.24 1.49 4.85 6.49 13.58 17.33 7.2929 15.70 10.94 8.12 2.91 0.27 0.21 0.20 1.25 4.12 5.65 11.86 15.21 6.3530 13.58 9.53 6.71 2.38 0.21 0.18 0.16 1.01 3.40 4.81 10.14 13.09 5.4231 11.45 8.12 5.29 1.86 0.16 0.14 0.12 0.78 2.67 3.98 8.41 10.97 4.4832 9.33 6.71 3.88 1.33 0.11 0.11 0.08 0.54 1.94 3.14 6.69 8.85 3.5533 7.21 5.30 2.47 0.80 0.05 0.08 0.04 0.30 1.22 2.31 4.97 6.73 2.61

17.2 34 8 5.09 3.90 1.06 0.28 0.00 0.05 0.00 0.06 0.49 1.47 3.24 4.61 1.6835 4.48 3.44 0.91 0.24 0.00 0.04 0.00 0.05 0.42 1.30 2.81 4.06 1.4736 3.87 2.99 0.77 0.20 0.00 0.03 0.00 0.04 0.35 1.12 2.39 3.51 1.2737 3.26 2.53 0.62 0.16 0.00 0.03 0.00 0.03 0.28 0.95 1.96 2.96 1.0638 2.66 2.08 0.48 0.12 0.00 0.02 0.00 0.02 0.21 0.78 1.53 2.42 0.8539 2.05 1.62 0.33 0.08 0.00 0.01 0.00 0.02 0.14 0.60 1.10 1.87 0.6540 1.44 1.17 0.18 0.04 0.00 0.01 0.00 0.01 0.07 0.43 0.67 1.32 0.44

20.8 41 9 0.84 0.71 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.26 0.24 0.78 0.2442 0.73 0.62 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.23 0.21 0.68 0.2143 0.62 0.52 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.19 0.17 0.59 0.1844 0.52 0.43 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.16 0.14 0.50 0.1545 0.41 0.34 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.13 0.10 0.41 0.1246 0.31 0.25 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.10 0.07 0.32 0.0947 0.20 0.15 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.07 0.03 0.23 0.06

24.5 48 10 0.10 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.00 0.13 0.0349 0.09 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 0.00 0.12 0.0250 0.07 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.10 0.0251 0.06 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00 0.08 0.0252 0.05 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.07 0.0153 0.04 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.05 0.0154 0.03 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.03 0.0155 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.02 0.00

28.5 56 11 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0057 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0058 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0059 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0060 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0061 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0062 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0063 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

32.7 64 12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.009.84 9.16 9.02 7.77 6.52 6.27 6.27 6.87 8.04 8.66 9.73 9.83 -Mean WS

39

40

Southern North SeaSignificant Wave Height – Average Percentage Exceedence Distribution

m Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.5 95.56 96.63 96.17 93.62 84.21 82.47 83.39 82.56 91.33 94.89 97.26 95.98 91.131 72.63 67.37 68.59 55.91 40.15 34.23 31.89 37.64 57.45 65.70 72.72 73.55 56.41

1.5 47.95 40.59 39.53 26.47 15.32 9.80 8.39 16.27 28.54 35.49 47.84 50.36 30.492 30.24 24.10 22.20 11.66 4.50 2.68 2.26 6.59 13.69 18.83 28.71 32.37 16.45

2.5 18.41 14.16 11.28 5.37 0.86 0.63 0.69 2.09 6.03 8.77 15.92 18.73 8.553 10.27 8.55 5.58 2.77 0.10 0.13 0.15 0.48 2.79 3.98 7.81 10.36 4.40

3.5 5.93 5.53 2.63 1.36 0.00 0.06 0.05 0.09 1.47 2.38 4.58 6.18 2.514 4.46 4.00 1.42 0.62 0.00 0.00 0.00 0.00 0.98 1.88 3.25 3.93 1.70

4.5 3.12 3.94 1.22 0.29 0.00 0.00 0.00 0.00 0.68 1.40 2.19 2.88 1.306 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

6.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.007 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

7.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.008 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

8.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Mean HSIG 1.68 1.56 1.49 1.24 0.98 0.90 0.89 0.98 1.26 1.41 1.64 1.71 -

41

Irish Sea

Mean Wind Speed – Average Percentage Exceedence Distributionm/s knots BF Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 0 0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.3 1 1 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.002 99.96 100.00 99.99 99.95 99.97 99.89 99.91 99.88 99.96 99.99 100.00 100.00 99.963 99.93 99.99 99.99 99.90 99.95 99.78 99.81 99.77 99.91 99.99 100.00 100.00 99.92

1.6 4 2 99.89 99.99 99.98 99.85 99.92 99.68 99.72 99.65 99.87 99.98 100.00 100.00 99.885 97.51 98.53 98.37 97.02 93.55 92.54 93.74 94.79 96.81 97.91 98.80 98.42 96.496 95.14 97.07 96.77 94.19 87.19 85.41 87.76 89.94 93.76 95.84 97.60 96.85 93.10

3.4 7 3 92.76 95.61 95.16 91.36 80.82 78.28 81.79 85.08 90.71 93.78 96.41 95.28 89.718 89.38 91.94 92.11 86.26 72.33 71.38 74.60 78.45 85.08 90.12 93.27 91.82 84.689 86.00 88.28 89.06 81.16 63.84 64.49 67.42 71.83 79.46 86.47 90.13 88.35 79.6510 82.61 84.62 86.01 76.06 55.35 57.59 60.24 65.20 73.83 82.81 86.99 84.89 74.62

5.5 11 4 79.23 80.96 82.96 70.96 46.86 50.70 53.06 58.58 68.21 79.16 83.85 81.42 69.5912 76.01 77.04 79.26 65.96 42.45 45.85 48.21 53.63 63.71 74.32 80.18 77.72 65.2913 72.78 73.13 75.56 60.97 38.04 41.00 43.36 48.69 59.22 69.47 76.52 74.02 60.9914 69.56 69.21 71.87 55.97 33.63 36.15 38.52 43.75 54.72 64.63 72.85 70.32 56.6915 66.34 65.30 68.17 50.98 29.23 31.31 33.67 38.81 50.23 59.78 69.19 66.62 52.3916 63.11 61.38 64.48 45.98 24.82 26.46 28.82 33.87 45.73 54.94 65.52 62.92 48.09

8 17 5 59.89 57.47 60.78 40.99 20.41 21.61 23.98 28.93 41.24 50.09 61.86 59.22 43.7918 55.32 52.58 55.36 36.01 17.24 18.22 20.25 24.65 36.70 44.43 56.48 55.08 39.2819 50.75 47.70 49.93 31.04 14.07 14.83 16.53 20.37 32.17 38.77 51.10 50.94 34.7820 46.17 42.82 44.51 26.07 10.91 11.45 12.81 16.09 27.64 33.10 45.71 46.80 30.2721 41.60 37.93 39.09 21.10 7.74 8.06 9.08 11.81 23.11 27.44 40.33 42.66 25.76

10.8 22 6 37.03 33.05 33.67 16.13 4.57 4.67 5.36 7.54 18.58 21.78 34.95 38.52 21.2623 33.53 29.59 29.76 13.99 3.86 3.97 4.52 6.42 16.41 19.13 31.09 35.07 18.8924 30.03 26.13 25.86 11.85 3.15 3.26 3.68 5.30 14.25 16.48 27.24 31.62 16.5225 26.53 22.66 21.95 9.72 2.44 2.56 2.84 4.19 12.09 13.84 23.38 28.18 14.1626 23.03 19.20 18.05 7.58 1.73 1.86 2.00 3.07 9.93 11.19 19.53 24.73 11.7927 19.53 15.74 14.14 5.44 1.02 1.15 1.16 1.95 7.77 8.54 15.67 21.28 9.42

13.9 28 7 16.04 12.28 10.24 3.30 0.31 0.45 0.32 0.84 5.61 5.89 11.82 17.83 7.0629 13.99 10.84 8.77 2.80 0.26 0.38 0.27 0.71 4.83 5.10 10.20 15.55 6.1230 11.95 9.40 7.30 2.30 0.21 0.30 0.21 0.58 4.05 4.31 8.58 13.27 5.1931 9.91 7.96 5.83 1.80 0.16 0.23 0.16 0.46 3.27 3.51 6.96 10.99 4.2632 7.87 6.52 4.35 1.29 0.11 0.15 0.11 0.33 2.49 2.72 5.34 8.71 3.3233 5.82 5.08 2.88 0.79 0.06 0.08 0.05 0.21 1.71 1.93 3.72 6.43 2.39

17.2 34 8 3.78 3.65 1.41 0.29 0.01 0.00 0.00 0.08 0.93 1.14 2.11 4.16 1.4635 3.33 3.23 1.22 0.25 0.00 0.00 0.00 0.07 0.82 1.01 1.84 3.62 1.2836 2.89 2.82 1.03 0.21 0.00 0.00 0.00 0.06 0.70 0.89 1.58 3.09 1.1037 2.44 2.41 0.84 0.17 0.00 0.00 0.00 0.05 0.59 0.76 1.31 2.56 0.9238 2.00 2.00 0.65 0.13 0.00 0.00 0.00 0.03 0.47 0.64 1.05 2.03 0.7439 1.55 1.58 0.46 0.09 0.00 0.00 0.00 0.02 0.36 0.51 0.78 1.49 0.5740 1.11 1.17 0.27 0.05 0.00 0.00 0.00 0.01 0.24 0.39 0.51 0.96 0.39

20.8 41 9 0.66 0.76 0.09 0.01 0.00 0.00 0.00 0.00 0.13 0.26 0.25 0.43 0.2142 0.58 0.67 0.07 0.01 0.00 0.00 0.00 0.00 0.11 0.23 0.21 0.38 0.1843 0.50 0.58 0.06 0.01 0.00 0.00 0.00 0.00 0.09 0.19 0.18 0.33 0.1644 0.42 0.49 0.05 0.01 0.00 0.00 0.00 0.00 0.07 0.16 0.14 0.28 0.1345 0.33 0.40 0.04 0.00 0.00 0.00 0.00 0.00 0.05 0.12 0.11 0.22 0.1046 0.25 0.31 0.02 0.00 0.00 0.00 0.00 0.00 0.04 0.09 0.07 0.17 0.0847 0.17 0.22 0.01 0.00 0.00 0.00 0.00 0.00 0.02 0.05 0.04 0.12 0.05

24.5 48 10 0.09 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.07 0.0349 0.08 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.06 0.0250 0.07 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.06 0.0251 0.06 0.08 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.05 0.0252 0.05 0.07 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.05 0.0153 0.03 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.04 0.0154 0.02 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.03 0.0155 0.01 0.02 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.00

28.5 56 11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.0057 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.0058 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.0059 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.0060 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.0061 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.0062 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.0063 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

32.7 64 12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.009.44 9.24 9.21 7.53 5.77 5.86 6.03 6.45 7.64 8.32 9.39 9.63 -Mean WS

42

Irish SeaSignificant Wave Height – Average Percentage Exceedence Distribution

m Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.5 91.18 93.66 91.95 83.02 63.35 66.17 66.18 71.60 78.57 87.39 92.13 90.14 81.201 69.98 69.49 71.91 48.06 24.76 26.28 27.47 32.24 46.31 55.17 70.83 67.80 50.74

1.5 51.44 49.02 51.36 24.34 8.48 8.50 8.49 12.27 25.27 32.90 48.74 51.47 30.932 35.96 30.55 30.86 11.83 2.06 2.51 2.37 4.28 12.72 17.12 29.63 36.99 18.02

2.5 23.42 18.78 15.08 5.71 0.66 0.71 0.49 1.54 6.09 7.82 15.01 24.58 9.963 13.77 10.89 7.56 2.51 0.22 0.25 0.11 0.46 2.86 3.49 7.84 15.56 5.44

3.5 13.84 11.15 7.23 2.22 0.09 0.00 0.00 0.54 1.64 3.21 7.18 15.91 5.234 8.11 6.80 3.59 1.33 0.00 0.00 0.00 0.03 0.73 1.87 4.09 9.50 2.99

4.5 4.50 5.01 2.03 0.51 0.00 0.00 0.00 0.00 0.37 0.58 1.70 4.75 1.606.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.008 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Mean HSIG 1.76 1.70 1.63 1.14 0.75 0.77 0.78 0.87 1.12 1.29 1.61 1.78 -

43

West of ShetlandsMean Wind Speed – Average Percentage Exceedence Distribution

m/s knots BF Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 0 0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.3 1 1 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.002 100.00 100.00 100.00 100.00 100.00 99.99 99.96 99.99 100.00 100.00 100.00 100.00 99.993 100.00 100.00 100.00 99.99 99.99 99.97 99.93 99.97 99.99 99.99 100.00 100.00 99.99

1.6 4 2 100.00 100.00 100.00 99.99 99.99 99.96 99.89 99.96 99.99 99.99 100.00 100.00 99.985 99.55 98.82 99.18 98.90 97.51 97.93 97.15 97.79 98.82 99.06 99.44 99.70 98.656 99.10 97.65 98.35 97.81 95.03 95.91 94.41 95.63 97.64 98.12 98.89 99.40 97.32

3.4 7 3 98.65 96.48 97.53 96.72 92.55 93.89 91.67 93.47 96.47 97.19 98.33 99.10 95.998 97.54 94.65 96.01 93.33 86.77 89.15 85.67 88.54 93.03 94.50 96.75 97.96 92.819 96.44 92.82 94.50 89.94 81.00 84.41 79.67 83.61 89.58 91.82 95.17 96.82 89.62

10 95.34 90.98 92.98 86.55 75.23 79.67 73.66 78.68 86.14 89.13 93.58 95.67 86.435.5 11 4 94.23 89.15 91.47 83.16 69.46 74.93 67.66 73.75 82.70 86.45 92.00 94.53 83.25

12 92.04 86.62 88.78 78.92 64.58 68.85 62.25 68.18 78.12 82.89 88.96 92.21 79.3213 89.85 84.09 86.10 74.67 59.70 62.77 56.83 62.62 73.54 79.33 85.92 89.89 75.3914 87.65 81.56 83.42 70.42 54.82 56.69 51.41 57.05 68.96 75.77 82.88 87.57 71.4615 85.46 79.03 80.74 66.17 49.94 50.62 45.99 51.49 64.37 72.21 79.84 85.25 67.5316 83.27 76.50 78.06 61.93 45.06 44.54 40.58 45.92 59.79 68.65 76.80 82.93 63.60

8 17 5 81.08 73.97 75.38 57.68 40.19 38.46 35.16 40.36 55.21 65.09 73.76 80.61 59.6718 76.84 69.45 70.61 52.10 35.30 32.96 30.10 35.20 49.86 59.66 68.59 75.60 54.6219 72.61 64.93 65.85 46.52 30.41 27.45 25.04 30.04 44.52 54.24 63.42 70.60 49.5620 68.38 60.40 61.08 40.94 25.53 21.95 19.98 24.89 39.17 48.82 58.25 65.59 44.5121 64.15 55.88 56.31 35.36 20.64 16.44 14.92 19.73 33.83 43.39 53.08 60.59 39.45

10.8 22 6 59.92 51.36 51.55 29.78 15.76 10.94 9.86 14.58 28.48 37.97 47.91 55.59 34.4023 55.74 47.43 47.04 26.11 13.68 9.38 8.39 12.62 25.62 34.21 43.59 50.90 31.1524 51.57 43.50 42.54 22.45 11.60 7.82 6.93 10.66 22.75 30.44 39.26 46.21 27.9125 47.40 39.57 38.04 18.79 9.52 6.26 5.47 8.69 19.89 26.68 34.93 41.53 24.6726 43.23 35.64 33.53 15.12 7.44 4.70 4.01 6.73 17.02 22.92 30.60 36.84 21.4227 39.05 31.71 29.03 11.46 5.36 3.14 2.55 4.77 14.16 19.15 26.28 32.15 18.18

13.9 28 7 34.88 27.78 24.53 7.80 3.28 1.58 1.09 2.81 11.29 15.39 21.95 27.47 14.9329 31.31 24.74 21.63 6.67 2.77 1.33 0.91 2.40 10.00 13.45 19.39 24.38 13.2030 27.73 21.69 18.73 5.54 2.26 1.09 0.74 2.00 8.70 11.51 16.83 21.30 11.4731 24.16 18.65 15.83 4.41 1.76 0.84 0.57 1.59 7.41 9.57 14.27 18.21 9.7432 20.59 15.60 12.93 3.28 1.25 0.59 0.39 1.18 6.11 7.63 11.71 15.13 8.0033 17.02 12.56 10.03 2.15 0.74 0.34 0.22 0.77 4.82 5.70 9.15 12.04 6.27

17.2 34 8 13.44 9.51 7.13 1.02 0.24 0.10 0.05 0.37 3.53 3.76 6.59 8.96 4.5435 11.99 8.36 6.20 0.88 0.20 0.08 0.04 0.32 3.13 3.32 5.74 7.91 4.0036 10.53 7.20 5.28 0.75 0.17 0.07 0.03 0.27 2.73 2.88 4.89 6.87 3.4637 9.08 6.05 4.35 0.61 0.14 0.05 0.03 0.22 2.33 2.45 4.04 5.82 2.9238 7.62 4.89 3.43 0.48 0.10 0.04 0.02 0.17 1.93 2.01 3.19 4.78 2.3839 6.17 3.74 2.50 0.35 0.07 0.03 0.01 0.12 1.53 1.57 2.34 3.73 1.8440 4.71 2.58 1.58 0.21 0.04 0.01 0.01 0.07 1.13 1.14 1.49 2.69 1.30

20.8 41 9 3.26 1.43 0.65 0.08 0.01 0.00 0.00 0.02 0.73 0.70 0.64 1.65 0.7642 2.86 1.25 0.57 0.07 0.00 0.00 0.00 0.02 0.64 0.61 0.55 1.44 0.6743 2.47 1.08 0.50 0.06 0.00 0.00 0.00 0.01 0.56 0.52 0.46 1.23 0.5744 2.08 0.90 0.42 0.05 0.00 0.00 0.00 0.01 0.47 0.43 0.37 1.02 0.4845 1.68 0.72 0.35 0.03 0.00 0.00 0.00 0.01 0.38 0.34 0.28 0.82 0.3846 1.29 0.55 0.27 0.02 0.00 0.00 0.00 0.01 0.29 0.25 0.19 0.61 0.2947 0.90 0.37 0.20 0.01 0.00 0.00 0.00 0.00 0.21 0.16 0.10 0.40 0.19

24.5 48 10 0.50 0.19 0.12 0.00 0.00 0.00 0.00 0.00 0.12 0.07 0.01 0.20 0.1049 0.45 0.17 0.11 0.00 0.00 0.00 0.00 0.00 0.10 0.06 0.01 0.18 0.0950 0.40 0.14 0.09 0.00 0.00 0.00 0.00 0.00 0.09 0.05 0.01 0.16 0.0851 0.35 0.12 0.08 0.00 0.00 0.00 0.00 0.00 0.08 0.04 0.01 0.14 0.0752 0.29 0.10 0.07 0.00 0.00 0.00 0.00 0.00 0.07 0.03 0.01 0.12 0.0653 0.24 0.07 0.05 0.00 0.00 0.00 0.00 0.00 0.05 0.03 0.00 0.11 0.0554 0.19 0.05 0.04 0.00 0.00 0.00 0.00 0.00 0.04 0.02 0.00 0.09 0.0355 0.14 0.02 0.03 0.00 0.00 0.00 0.00 0.00 0.03 0.01 0.00 0.07 0.02

28.5 56 11 0.09 0.00 0.02 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.05 0.0157 0.08 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.05 0.0158 0.08 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.04 0.0159 0.07 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.04 0.0160 0.07 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.03 0.0161 0.06 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.03 0.0162 0.06 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.0163 0.06 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.01

32.7 64 12 0.05 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.0112.17 11.13 11.04 8.94 7.49 7.39 7.03 7.56 9.05 9.83 10.80 11.59 -Mean WS

44

West of Shetlands

Significant Wave Height – Average Percentage Exceedence Distributionm Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year0 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00

0.5 100.00 100.00 100.00 99.95 99.89 100.00 99.81 100.00 100.00 100.00 100.00 100.00 99.971 99.92 98.96 98.74 97.74 87.27 89.12 79.19 85.79 94.04 99.34 99.61 100.00 94.10

1.5 99.49 92.87 96.95 84.01 55.64 51.89 45.32 52.15 75.58 86.39 94.97 99.76 77.812 96.45 85.21 90.84 61.47 33.06 24.63 21.12 28.77 55.06 68.02 84.56 94.30 61.83

2.5 85.37 74.20 78.61 43.14 18.85 10.94 9.46 15.73 39.20 50.89 69.22 81.53 47.973 71.92 59.98 65.20 28.40 10.34 5.03 3.72 7.91 26.63 35.57 53.28 65.70 36.04

3.5 59.37 46.85 50.68 17.66 5.95 1.99 1.38 3.51 17.94 24.57 39.21 50.00 26.514 48.65 36.66 38.01 10.23 3.87 0.51 0.35 1.63 12.20 16.73 27.67 36.78 19.38

4.5 37.97 27.41 28.82 6.52 2.61 0.07 0.07 0.66 8.60 11.44 18.80 27.38 14.165 29.05 20.59 20.81 4.22 1.63 0.00 0.01 0.25 5.98 7.73 12.52 19.09 10.12

5.5 22.34 15.61 14.42 2.57 0.96 0.00 0.00 0.17 3.85 5.00 8.01 13.05 7.146 16.98 11.57 9.35 1.51 0.50 0.00 0.00 0.12 2.54 3.24 5.24 8.91 4.97

6.5 13.31 8.78 6.24 0.90 0.14 0.00 0.00 0.08 1.88 2.41 3.54 6.16 3.607 10.47 6.53 3.98 0.52 0.06 0.00 0.00 0.03 1.60 1.92 2.51 4.34 2.65

7.5 8.27 4.66 2.67 0.37 0.02 0.00 0.00 0.00 1.36 1.44 1.86 3.13 1.978 6.50 3.32 1.92 0.22 0.01 0.00 0.00 0.00 1.09 1.14 1.33 2.26 1.48

8.5 4.99 2.53 1.35 0.18 0.00 0.00 0.00 0.00 0.90 0.91 0.99 1.77 1.1314.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.0015 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

15.5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Mean HSIG 4.36 3.75 3.80 2.55 1.85 1.67 1.56 1.74 2.50 2.84 3.37 3.83 -

45

APPENDIX 2 RESULTS OF DETAILED ANALYSIS 1 TRIALS BY SEASON AND Hs

Dataset ‘B’ rescue craft trials

Dataset ‘B’ MRD trials

0

10

20

30

40

50

60

70

80

90

100

January February March April May June July August September October November December N/R

M onth

Num

ber o

f res

cue

craf

t tria

ls

Hs = >3.5mHs = 2.0m - 3.5mHs = 1.0m - <2.0mHs = <1.0m

0

20

40

60

80

100

120

January February March April May June July August September October November December N/R

M onth

Num

ber o

f MR

D tr

ials

Hs = >3.5mHs = 2.0m - 3.5mHs = 1.0m - <2.0mHs = <1.0m

46

Dataset ‘A’ FRC trials

Dataset ‘A’ DC trials

0

100

200

300

400

500

600

January February March April May June July August September October November December N/R

M onth

Num

ber o

f FR

C tr

ials

Hs = >3.5mHs = 2.0m - 3.5mHs = 1.0m - <2.0mHs = <1.0m

0

50

100

150

200

250

January February March April May June July August September October November December N/R

M onth

Num

ber o

f DC

tria

ls

Hs = >3.5mHs = 2.0m - 3.5mHs = 1.0m - <2.0mHs = <1.0m

47

Dataset ‘B’ rescue craft trials

Dataset ‘B’ MRD trials

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Jan-99 Jun-99 Dec-99 Jun-00 Dec-00 Jun-01 Dec-01 Jun-02 Dec-02 Jun-03 Dec-03

Date

Sign

ifica

nt w

ave

heig

ht (m

)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Jan-99 Jun-99 Dec-99 Jun-00 Dec-00 Jun-01 Dec-01 Jun-02 Dec-02 Jun-03 Dec-03

Date

Sign

ifica

nt w

ave

heig

ht (m

)

48

Dataset ‘A’ FRC trials

Dataset ‘A’ DC trials

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

01-Jan-05 02-Mar-05 01-May-05 30-Jun-05 29-Aug-05

Date

Sign

ifica

nt w

ave

heig

ht (m

)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

01-Jan-05 02-Mar-05 01-May-05 30-Jun-05 29-Aug-05

Date

Sign

ifica

nt w

ave

heig

ht (m

)

49

2 TRIALS ON FORMER VESSEL TYPES BY Hs

Dataset ‘B’ rescue craft trials

Dataset ‘B’ MRD trials

0

50

100

150

200

250

300

350

400

<1m 1m - <2m 2m - 3.5m >3.5m

Significant wave height (m)

Num

ber

of re

scue

cra

ft tr

ials

Supply vesselPurpose builtFishing vesselAnchor handler

0

50

100

150

200

250

300

350

400

<1m 1m - <2m 2m - 3.5m >3.5m

Significant wave height (m)

Num

ber o

f MR

D tr

ials

Supply vesselPurpose builtFishing vesselAnchor handler

50

Dataset ‘A’ FRC trials

Dataset ‘A’ DC trials

0

100

200

300

400

500

600

700

800

900

1000

<1m 1m - <2m 2m - 3.5m >3.5m

Significant wave height (m)

Num

ber

of F

RC

tria

ls

Supply vessel

Purpose builtFishing vessel

Anchor handler

0

50

100

150

200

250

<1m 1m - <2m 2m - 3.5m >3.5m

Significant wave height (m)

Num

ber

of D

C tr

ials

Supply vesselPurpose built

Fishing vesselAnchor handler

51

3 TRIALS IN PREVAILING CONDITIONS AGAINST EXCEEDENCE DATA 3.1 Trials based on dataset ‘B’

Rescue craft trials by UKCS area and Hs

MRD trials by UKCS area and Hs

0

50

100

150

200

250

300

350

400

<1m 1m - <2m 2m - 3.5m >3.5m

Significant wave height (m)

Num

ber

of r

escu

e cr

aft t

rial

s

West of ShetlandsNorthern North SeaCentral North SeaSouthern North Sea

0

50

100

150

200

250

300

350

400

<1m 1m - <2m 2m - 3.5m >3.5m

Significant wave height (m)

Num

ber

of M

RD

tria

ls

West of ShetlandsNorthern North SeaCentral North SeaSouthern North Sea

52

NB: Chart based on 796 trials Percentage of all dataset ‘B’ rescue craft trials carried out in

percentage of average maximum wind speeds

Count of all dataset ‘B’ rescue craft trials carried out at each 1% exceedence of average maximum wind speeds

0%

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Percentage of average maximum wind speeds

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Percentage of average maximum wind speeds

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53

NB: Chart based on 303 trials Percentage of NNS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum wind speeds

Count of NNS dataset ‘B’ rescue craft trials carried out at each

1% exceedence of average maximum wind speeds

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Percentage of average maximum wind speeds

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Percentage of average maximum wind speeds

Num

ber o

f FR

C tr

ials

in N

NS

54

NB: Chart based on 455 trials Percentage of CNS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum wind speeds

Count of CNS dataset ‘B’ rescue craft trials carried out at each

1% exceedence of average maximum wind speeds

0%

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Percentage of average maximum wind speeds

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CN

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Percentage of average maximum wind speeds

Num

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ials

in C

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55

NB: Chart based on 28 trials Percentage of SNS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum wind speeds

Count of SNS dataset ‘B’ rescue craft trials carried out at each

1% exceedence of average maximum wind speeds

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Percentage of average maximum wind speeds

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Percentage of average maximum wind speeds

Num

ber

of F

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ials

in S

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56

NB: Chart based on 10 trials Percentage of WofS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum wind speeds

Count of WofS dataset ‘B’ rescue craft trials carried out at each

1% exceedence of average maximum wind speeds

0%

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Percentage of average maximum wind speeds

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ofS

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Percentage of average maximum wind speeds

Num

ber

of F

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57

NB: Chart based on 796 trials Percentage of all dataset ‘B’ rescue craft trials carried out in

percentage of average maximum significant wave height

Count of all dataset ‘B’ rescue craft trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

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Percentage of average maximum significant wave height

Num

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58

NB: Chart based on 303 trials Percentage of NNS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum significant wave height

Count of NNS dataset ‘B’ rescue craft trials carried out at each 1% exceedence of average maximum significant wave height

0%

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Percentage of average maximum significant wave height

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Percentage of average maximum significant wave height

Num

ber

of F

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ials

in N

NS

59

NB: Chart based on 455 trials Percentage of CNS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum significant wave height

Count of CNS dataset ‘B’ rescue craft trials carried out at each 1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

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CN

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Percentage of average maximum significant wave he ight

Num

ber o

f FR

C tr

ials

in C

NS

60

NB: Chart based on 28 trials Percentage of SNS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum significant wave height

Count of SNS dataset ‘B’ rescue craft trials carried out at each 1% exceedence of average maximum significant wave height

0%

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Percentage of average maximum significant wave height

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0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Percentage of average maximum significant wave height

Num

ber

of F

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ls in

SN

S

61

NB: Chart based on 10 trials Percentage of WofS dataset ‘B’ rescue craft trials carried out in

percentage of average maximum significant wave height

Count of WofS dataset ‘B’ rescue craft trials carried out at each 1% exceedence of average maximum significant wave height

0%

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Percentage of average maximum significant wave height

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0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Percentage of average maximum significant wave height

Num

ber o

f FR

C tr

ials

Wof

S

62

NB: Chart based on 715 trials Percentage of all dataset ‘B’ MRD trials carried out in

percentage of average maximum wind speeds

Count of all dataset ‘B’ MRD trials carried out at each 1% exceedence of average maximum wind speeds

0%

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Percentage of average maximum wind speeds

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Percentage of average maximum wind speeds

Num

ber

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RD

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ls

63

NB: Chart based on 192 trials Percentage of NNS dataset ‘B’ MRD trials carried out in

percentage of average maximum wind speeds

Count of NNS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

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in N

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Percentage of average maximum wind speeds

Num

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f MRD

tria

ls in

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S

64

NB: Chart based on 462 trials Percentage of CNS dataset ‘B’ MRD trials carried out in

percentage of average maximum wind speeds

Count of CNS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum wind speeds

0%

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Percentage of average maximum wind speeds

Num

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65

NB: Chart based on 39 trials Percentage of SNS dataset ‘B’ MRD trials carried out in

percentage of average maximum wind speeds

Count of SNS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum wind speeds

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Percentage of average maximum wind speeds

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in

SNS

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Percentage of average maximum wind speeds

Num

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ls in

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66

NB: Chart based on 22 trials Percentage of WofS dataset ‘B’ MRD trials carried out in

percentage of average maximum wind speeds

Count of WofS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum wind speeds

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Percentage of average maximum wind speeds

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Percentage of average maximum wind speeds

Num

ber o

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67

NB: Chart based on 719 trials Percentage of all dataset ‘B’ MRD trials carried out in

percentage of average maximum significant wave height

Count of all dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum significant wave height

0%

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Percentage of average maximum significant wave height

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Percentage of average maximum significant wave height

Num

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68

NB: Chart based on 192 trials Percentage of NNS dataset ‘B’ MRD trials carried out in percentage of average maximum significant wave height

Count of NNS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum significant wave height

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Percentage of average maximum significant wave height

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in N

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Percentage of average maximum significant wave height

Num

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69

NB: Chart based on 466 trials Percentage of CNS dataset ‘B’ MRD trials carried out in percentage of average maximum significant wave height

Count of CNS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum significant wave height

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Percentage of average maximum significant wave he ight

Num

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f MR

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ials

in C

NS

70

NB: Chart based on 39 trials Percentage of SNS dataset ‘B’ MRD trials carried out in percentage of average maximum significant wave height

Count of SNS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum significant wave height

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in S

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8

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%

Percentage of average maximum significant wave he ight

Num

ber o

f MR

D tr

ials

in S

NS

71

NB: Chart based on 22 trials Percentage of WofS dataset ‘B’ MRD trials carried out in percentage of average maximum significant wave height

Count of WofS dataset ‘B’ MRD trials carried out at each

1% exceedence of average maximum significant wave height

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Percentage of average maximum significant wave height

Num

ber o

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72

3.2 Trials based on dataset ‘A’ data

FRC trials by UKCS area and Hs

DC trials by UKCS area and Hs

0

100

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<1m 1m - <2m 2m - 3.5m >3.5m

Significant wave height (m)

Num

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Irish SeaWest of ShetlandsNorthern North SeaCentral North SeaSouthern North Sea

0

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Significant wave height (m)

Num

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of D

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ials

Irish SeaWest of ShetlandsNorthern North SeaCentral North SeaSouthern North Sea

73

NB: Chart based on 1267 trials Percentage of all dataset ‘A’ FRC trials carried out in

percentage of average maximum wind speeds

Count of all dataset ‘A’ FRC trials carried out at each 1% exceedence of average maximum wind speeds

0%

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Percentage of average maximum wind speeds

Num

ber o

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74

NB: Chart based on 404 trials Percentage of NNS dataset ‘A’ FRC trials carried out in

percentage of average maximum wind speeds

Count of NNS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum wind speeds

0%

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Percentage of average maximum wind speeds

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ls in

NN

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Percentage of average maximum wind speeds

Num

ber o

f FRC

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ls in

NNS

75

NB: Chart based on 748 trials Percentage of CNS dataset ‘A’ FRC trials carried out in

percentage of average maximum wind speeds

Count of CNS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

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f all

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Percentage of average maximum wind speeds

Num

ber o

f FRC

tria

ls in

CNS

76

NB: Chart based on 18 trials Percentage of SNS dataset ‘A’ FRC trials carried out in

percentage of average maximum wind speeds

Count of SNS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

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SN

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Percentage of average maximum wind speeds

Num

ber o

f FRC

tria

ls in

SNS

77

NB: Chart based on 67 trials Percentage of IS dataset ‘A’ FRC trials carried out in

percentage of average maximum wind speeds

Count of IS dataset ‘A’ FRC trials carried out at each 1% exceedence of average maximum wind speeds

0%

10%

20%

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Percentage of average maximum wind speeds

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f all

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tria

ls in

IS

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18

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Percentage of average maximum wind speeds

Num

ber o

f FRC

tria

ls in

IS

78

NB: Chart based on 30 trials Percentage of WofS dataset ‘A’ FRC trials carried out in

percentage of average maximum wind speeds

Count of WofS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

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ls W

ofS

0

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7

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Percentage of average maximum wind speeds

Num

ber

of F

RC tr

ials

Wof

S

79

NB: Chart based on 1294 trials Percentage of all dataset ‘A’ FRC trials carried out in

percentage of average maximum significant wave height

Count of all dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

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Percentage of average maximum significant wave height

Num

ber o

f FR

C tr

ials

80

NB: Chart based on 389 trials Percentage of NNS dataset ‘A’ FRC trials carried out in

percentage of average maximum significant wave height

Count of NNS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

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f all

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tria

ls in

NN

S

0

5

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20

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30

35

40

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Percentage of average maximum significant wave height

Num

ber o

f FRC

tria

ls in

NNS

81

NB: Chart based on 776 trials Percentage of CNS dataset ‘A’ FRC trials carried out in

percentage of average maximum significant wave height

Count of CNS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

Perc

enta

ge o

f all

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trial

s in

CNS

0

20

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0% 5% 10%

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Percentage of average maximum significant wave he ight

Num

ber o

f FR

C tr

ials

in C

NS

82

NB: Chart based on 18 trials Percentage of SNS dataset ‘A’ FRC trials carried out in

percentage of average maximum significant wave height

Count of SNS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

20%

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Percentage of average maximum significant wave he ight

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f all

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tria

ls in

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S

0

1

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4

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7

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Percentage of average maximum significant wave height

Num

ber o

f FRC

tria

ls in

SNS

83

NB: Chart based on 66 trials Percentage of IS dataset ‘A’ FRC trials carried out in

percentage of average maximum significant wave height

Count of IS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

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IS

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Percentage of average maximum significant wave height

Num

ber o

f FRC

tria

ls in

IS

84

NB: Chart based on 45 trials Percentage of WofS dataset ‘A’ FRC trials carried out in percentage of average maximum significant wave height

Count of WofS dataset ‘A’ FRC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

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f all

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tria

ls W

ofS

0

2

4

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12

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Percentage of average maximum significant wave height

Num

ber o

f FRC

tria

ls W

ofS

85

NB: Chart based on 422 trials Percentage of all dataset ‘A’ DC trials carried out in

percentage of average maximum wind speeds

Count of all dataset ‘A’ DC trials carried out at each 1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

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tria

ls

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Percentage of average maximum wind speeds

Num

ber o

f DC

trial

s

86

NB: Chart based on 208 trials Percentage of NNS dataset ‘A’ DC trials carried out in

percentage of average maximum wind speeds

Count of NNS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

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ls in

NN

S

0

5

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Percentage of average maximum wind speeds

Num

ber o

f DC

trial

s in

NNS

87

NB: Chart based on 192 trials Percentage of CNS dataset ‘A’ DC trials carried out in

percentage of average maximum wind speeds

Count of CNS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

20%

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Percentage of average maximum wind speeds

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f all

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S

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Percentage of average maximum wind speeds

Num

ber o

f DC

trial

s in

CNS

88

NB: Chart based on 8 trials Percentage of SNS dataset ‘A’ DC trials carried out in

percentage of average maximum wind speeds

Count of SNS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

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ls in

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S

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Percentage of average maximum wind speeds

Num

ber o

f DC

trial

s in

SNS

89

NB: Chart based on 8 trials Percentage of IS dataset ‘A’ DC trials carried out in

percentage of average maximum wind speeds

Count of IS dataset ‘A’ DC trials carried out at each 1% exceedence of average maximum wind speeds

0%

10%

20%

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Percentage of average maximum wind speeds

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f all

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tria

ls in

IS

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Percentage of average maximum wind speeds

Num

ber o

f DC

trial

s in

IS

90

NB: Chart based on 6 trials Percentage of WofS dataset ‘A’ DC trials carried out in

percentage of average maximum wind speeds

Count of WofS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum wind speeds

0%

10%

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Percentage of average maximum wind speeds

Perc

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f all

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tria

ls W

ofS

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Percentage of average maximum wind speeds

Num

ber o

f DC

trial

s W

ofS

91

NB: Chart based on 428 trials Percentage of all dataset ‘A’ DC trials carried out in

percentage of average maximum significant wave height

Count of all dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

Perc

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f all

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Percentage of average maximum significant wave height

Num

ber o

f DC

trial

s

92

NB: Chart based on 200 trials Percentage of NNS dataset ‘A’ DC trials carried out in

percentage of average maximum significant wave height

Count of NNS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

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Percentage of average maximum significant wave height

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f all

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tria

ls in

NN

S

0

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Percentage of average maximum significant wave height

Num

ber o

f DC

trial

s in

NNS

93

NB: Chart based on 206 trials Percentage of CNS dataset ‘A’ DC trials carried out in

percentage of average maximum significant wave height

Count of CNS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum significant wave height

0

10

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Percentage of average maximum significant wave height

Num

ber o

f DC

trial

s in

CNS

0%

10%

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100%

0% 5% 10%

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Percentage of average maximum significant wave height

Perc

enta

ge o

f all

DC

tria

ls in

CN

S

94

NB: Chart based on 8 trials Percentage of SNS dataset ‘A’ DC trials carried out in

percentage of average maximum significant wave height

Count of SNS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

20%

30%

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Percentage of average maximum significant wave height

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f all

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tria

ls in

SN

S

0

1

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Percentage of average maximum significant wave height

Num

ber o

f DC

trial

s in

SNS

95

NB: Chart based on 8 trials Percentage of IS dataset ‘A’ DC trials carried out in

percentage of average maximum significant wave height

Count of IS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

20%

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Percentage of average maximum significant wave height

Perc

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f all

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tria

ls in

IS

0

1

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3

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Percentage of average maximum significant wave height

Num

ber o

f DC

trial

s in

IS

96

NB: Chart based on 6 trials Percentage of WofS dataset ‘A’ DC trials carried out in

percentage of average maximum significant wave height

Count of WofS dataset ‘A’ DC trials carried out at each

1% exceedence of average maximum significant wave height

0%

10%

20%

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Percentage of average maximum significant wave height

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tria

ls W

ofS

0

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Percentage of average maximum significant wave height

Num

ber o

f DC

trial

s W

ofS

97

4 AVERAGE EXERCISE TIMES OF TARGET RECOVERY TRIALS 4.1 Trials of rescue craft

Number of rescue craft recovery trials involving 2 targets (total = 85 trials) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 11 2 2 2 0 0 0 0 0 0 2 24 7 3 2 0 2 0 0 0 0 3 20 6 0 2 0 2 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 2 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 7.7 7.0 14.0 16.0 - - - - - - 2 7.1 10.7 14.5 16.0 - 19.0 - - - - 3 9.2 13.2 - 22.0 - 26.5 - - - - 4 - - - - - - - - - -

Average time to recover 2 targets by rescue craft at various ranges

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Ave

rage

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

98

0 3 0 0 0 0 0 4 2 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 3 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 8.2 8.0 10.5 - - - - - - - 2 9.4 6.0 17.3 27.0 22.0 - - - - - 3 10.0 12.0 15.0 - 23.0 - - - - - 4 30.0 - - - - - - - - -

Average time to recover 3 targets by rescue craft at various ranges

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 13 2 0 0 0 0 0 0 0 2 15 2 2 2 0 0 0 0 0 3 11 6

3 4 2

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

99

Number of rescue craft recovery trials involving 3 targets (total = 67 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 2 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 3 2 0 2 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 4 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 14.0 - - - - - - - - - 2 - - - - - - - - - - 3 7.0 - 20.0 - - - - - - - 4 - - - - - - - - - -

Average time to recover 4 targets by rescue craft at various ranges

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

100

Number of rescue craft recovery trials involving 4 targets (total = 6 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 2 0 0 0 0 0 0 0 0 0 2 3 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 5 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 11.0 - - - - - - - - - 2 8.0 - - - - - - - - - 3 - - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 5 targets by rescue craft at various ranges

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Ave

rage

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

101

Number of rescue craft recovery trials involving 5 targets (total = 5 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 2 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 8 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 16.0 - - - - - - - - - 2 - - - - - - - - - - 3 - - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 8 targets by rescue craft at various ranges

0

2

4

6

8

10

12

14

16

18

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

102

Number of rescue craft recovery trials involving 8 targets (total = 2 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 2 0 0 0 3 0 0 0 0 0 2 0 2 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 10 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 - - - - - - 63.0 - - - 3 - - - - - 69.0 - 83.0 - - 4 - - - - - - - - - -

Average time to recover 10 targets by rescue craft at various ranges

0

10

20

30

40

50

60

70

80

90

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

103

Number of rescue craft recovery trials involving 10 targets (total = 6 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 0 0 0 0 0 0 0 0 0 2 0 2 0 0 0 0 0 0 2 0 3 2 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 12 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 - 17.0 - - - - - - 40.0 - 3 11.0 - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 12 targets by rescue craft at various ranges

0

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Ave

rage

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

104

Number of rescue craft recovery trials involving 12 targets (total = 6 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 0 0 0 0 2 0 0 0 0 2 0 0 0 0 0 0 0 0 0 2 3 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 14 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - 40.0 - - - - 2 - - - - - - - - - 103.0 3 - - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 14 targets by rescue craft at various ranges

0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

105

Number of rescue craft recovery trials involving 14 targets (total = 4 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 3 2 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 17 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 - - - - - - - - - - 3 18.0 - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 17 targets by rescue craft at various ranges

0

2

4

6

8

10

12

14

16

18

20

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

106

Number of rescue craft recovery trials involving 17 targets (total = 2 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 2 0 0 0 0 0 0 0 0 2 3 3 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average rescue craft recovery times for 20 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - 29.0 - - - - - - - - 2 24.7 24.0 - - - - - - - - 3 - - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 20 targets by rescue craft at various ranges

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

107

Number of rescue craft recovery trials involving 20 targets (total = 8 trials)

Number of MRD trials involving 1 target (total = 62 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 6 2 3 0 0 0 0 0 0 0 2 22 2 0 3 0 0 0 0 0 0 3 14 4 2 0 0 0 0 0 0 0 4 2 2 0 0 0 0 0 0 0 0

Average MRD times for 1 target (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 9.6 8.0 14.0 - - - - - - - 2 13.6 16.0 - 12.0 - - - - - - 3 16.2 23.0 14.0 - - - - - - - 4 12.0 13.0 - - - - - - - -

Average time to recover 1 target by MRD at various ranges

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

108

4.2 Trials of MRD

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 9 0 0 0 0 0 0 0 0 0 2 14 4 0 0 0 0 0 0 0 0 3 12 2 2 0 0 0 0 0 0 0 4 5 0 0 0 0 0 0 0 0 0

Average MRD times for 2 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 9.8 - - - - - - - - - 2 10.9 12.3 - - - - - - - - 3 17.2 17.0 25.0 - - - - - - - 4 11.8 - - - - - - - - -

Average time to recover 2 targets by MRD at various ranges

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Ave

rage

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

109

Number of MRD trials involving 2 targets (total = 48 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 3 0 0 0 0 0 0 0 0 0 2 14 3 0 0 0 0 0 0 0 0 3 17 5 0 0 0 0 0 0 0 0 4 3 4 0 0 0 0 0 0 0 0

Average MRD times for 3 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 16.5 - - - - - - - - - 2 13.5 16.0 - - - - - - - - 3 20.2 19.5 - - - - - - - - 4 31.0 19.3 - - - - - - - -

Average time to recover 3 targets by MRD at various ranges

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

110

Number of MRD trials involving 3 targets (total = 49 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 8 3 0 0 0 0 0 0 0 0 2 24 4 0 0 0 0 0 0 0 0 3 30 6 3 0 0 0 0 0 0 0 4 5 0 0 0 0 0 0 0 0 0

Average MRD times for 4 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 19.4 23.5 - - - - - - - - 2 19.3 26.7 - - - - - - - - 3 22.6 17.6 27.5 - - - - - - - 4 25.8 - - - - - - - - -

Average time to recover 4 targets by MRD at various ranges

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

111

Number of MRD trials involving 4 targets (total = 83 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 0 0 0 0 0 0 0 0 0 2 4 2 0 0 0 0 0 0 0 0 3 9 5 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 5 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 26.0 20.0 - - - - - - - - 3 22.8 29.0 - - - - - - - - 4 - - - - - - - - - -

Average time to recover 5 targets by MRD at various ranges

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

112

Number of MRD trials involving 5 targets (total = 20 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 4 0 0 0 0 0 0 0 0 0 2 8 3 0 0 0 0 0 0 0 0 3 15 5 0 0 0 0 0 0 0 0 4 2 0 0 0 0 0 0 0 0 0

Average MRD times for 6 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 30.0 - - - - - - - - - 2 30.9 23.5 - - - - - - - - 3 29.5 30.3 - - - - - - - - 4 55.0 - - - - - - - - -

Average time to recover 6 targets by MRD at various ranges

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

113

Number of MRD trials involving 6 targets (total = 37 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 0 0 0 0 0 0 0 0 0 2 2 0 0 0 0 0 0 0 0 0 3 2 0 0 0 0 0 0 0 0 0 4 2 0 0 0 0 0 0 0 0 0

Average MRD times for 7 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 40.0 - - - - - - - - - 3 25.0 - - - - - - - - - 4 25.0 - - - - - - - - -

Average time to recover 7 targets by MRD at various ranges

0

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

114

Number of MRD trials involving 7 targets (total = 6 trials)

Average time to recover 8 targets by MRD at various ranges

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 0 0 0 0 0 0 0 0 0 0 2 3 2 0 0 0 0 0 0 0 0 3 8 2 2 0 0 0 0 0 0 0 4 3 0 0 0 0 0 0 0 0 0

Average MRD times for 8 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 34.5 34.0 - - - - - - - - 3 32.4 50.0 79.0 - - - - - - - 4 31.0 - - - - - - - - -

0

10

20

30

40

50

60

70

80

90

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

115

Number of MRD trials involving 8 targets (total = 20 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 8 9 10 7

1 2 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 3 3 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 9 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 46.0 - - - - - - - - - 2 - - - - - - - - - - 3 38.0 - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 9 targets by MRD at various ranges

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

116

Number of MRD trials involving 9 targets (total = 5 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 2 0 0 0 0 0 0 0 0 0 2 3 2 0 0 0 0 0 0 0 0 3 9 2 0 0 0 0 0 0 0 0 4 2 0 0 0 0 0 0 0 0 0

Average MRD times for 10 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 43.0 - - - - - - - - - 2 30.0 30.0 - - - - - - - - 3 35.6 64.0 - - - - - - - - 4 25.0 - - - - - - - - -

Average time to recover 10 targets by MRD at various ranges

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

117

Number of MRD trials involving 10 targets (total = 20 trials)

Distance (bin) Hs (bin) 1 2 3 4 5 6 7 8 9 10

1 3 2 2 0 0 2 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 3 4 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 12 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 48.0 55.0 76.0 - - 95.0 - - - - 2 - - - - - - - - - - 3 25.3 - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 12 targets by MRD at various ranges

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Ave

rage

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

118

Number of MRD trials involving 12 targets (total = 13 trials)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 2 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 13 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 - - - - - 60.0 - - - - 3 - - - - - - - - - - 4 - - - - - - - - - -

Average time to recover 13 targets by MRD at various ranges

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

119

Number of MRD trials involving 13 targets (total = 2 trials) Distance (bin)

1 8 6 2 0 0 2 0 0 2 0 2 0 2 0 0 0 0 0 0 0 0 3 2 3 0 0 0 0 2 0 2 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 14 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 36.0 47.8 47.0 - - 115.0 - - 39.0 - 2 37.0 - - - - - - - - 3 40.0 54.5 - - - - 90.0 - 88.0 - 4 - - - - - - - - - -

Average time to recover 14 targets by MRD at various ranges

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

Hs (bin) 1 2 3 4 5 6 7 8 9 10

120

Number of MRD trials involving 14 targets (total = 31 trials) Distance (bin)

1 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 3 0 0 0 2 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 15 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - - - - - - - - - - 2 - - - - - - - - - - 3 - - - 35.0 - - - - - - 4 - - - - - - - - - -

Average time to recover 15 targets by MRD at various ranges

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

Hs (bin) 1 2 3 4 5 6 7 8 9 10

121

Number of MRD trials involving 15 targets (total = 2 trials)

Distance (bin)

1 0 2 3 2 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 3 3 0 2 2 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 18 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - 42.0 35.8 32.0 - - - - - - 2 - - - - - - - - - - 3 57.0 - 86.6 84.0 - - - - - - 4 - - - - - - - - - -

Average time to recover 18 targets by MRD at various ranges

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

Hs (bin) 1 2 3 4 5 6 7 8 9 10

122

Number of MRD trials involving 18 targets (total = 14 trials)

Distance (bin)

1 2 0 0 0 0 0 0 0 0 0 2 0 2 0 2 0 2 0 0 0 0 3 0 3 2 3 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 21 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 78.6 - - - - - - - - - 2 - 34.0 - 65.0 - - - - - - 3 - 66.7 73.5 72.8 - 77.9 - - - - 4 - - - - - - - - - -

Average time to recover 21 targets by MRD at various ranges

0

10

20

30

40

50

60

70

80

90

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

Hs (bin) 1 2 3 4 5 6 7 8 9 10

123

Number of MRD trials involving 21 targets (total = 16 trials)

Distance (bin)

1 2 0 0 0 0 0 0 0 0 0 2 0 0 2 0 2 2 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 4 0 2 0 0 0 0 0 0 0 0

Average MRD times for 25 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 61.7 - - - - - - - - - 2 - - 76.4 - 46.5 87.8 - - - - 3 - - - - - - - - - - 4 - 55.0 - - - - - - - -

Average time to recover 25 targets by MRD at various ranges

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

Hs (bin) 1 2 3 4 5 6 7 8 9 10

124

Number of MRD trials involving 25 targets (total = 10 trials)

Distance (bin)

1 0 2 0 0 0 0 0 0 0 0 2 2 3 0 0 0 0 0 0 0 0 3 0 5 2 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0 0

Average MRD times for 30 targets (mins.) Distance (bin)

Hs (bin) 1 2 3 4 5 6 7 8 9 10 1 - 92.0 - - - - - - - - 2 49.0 71.5 - - - - - - - - 3 - 67.3 49.0 - - - - - - - 4 - - - - - - - - - -

Average time to recover 30 targets by MRD at various ranges

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10

Target distance (bin)

Aver

age

reco

very

tim

e (m

ins.

)

Hs = <1.0m

Hs = 1.0m - <2.0m

Hs = 2.0m - 3.5m

Hs = >3.5m

Hs (bin) 1 2 3 4 5 6 7 8 9 10

125

Number of MRD trials involving 30 targets (total = 14 trials)

Distance (bin)

Published by the Health and Safety Executive 07/07

Analysis of ERRV trials datafrom ERRVA and Seacroft

Health and Safety Executive

RR569

www.hse.gov.uk

For a number of years data have been collected byseveral parties recording the frequency, circumstancesand prevailing conditions when ERRVs on the UKCScarried out trials with their rescue craft. Some data havebeen collected as part of independently witnessedvalidation trials whereas others, gathered as part of anindustry initiative to improve standards, was recorded bythe vessels' crew. In themselves the benefit of theindividual records is somewhat limited but whencombined with the results of other trials carried out in thesame UKCS area it is possible to define trends andsimilarities. By introducing wind and wave data fromhindcast surveys and comparing this with the season andtrial location it is possible to determine the severity ofconditions at the time of trial compared to the average tobe expected. These factors were investigated in detailduring the course of the study and results obtained for arange of activities; trials with rescue craft or mechanicalrecovery devices, single or multiple survivor recovery, andrecovery at different ranges from the ERRV. Continueddata collection and analysis in the future may be used todemonstrate enhanced capabilities of both crew andequipment.

This report and the work it describes were funded bythe Health and Safety Executive (HSE). Its contents,including any opinions and/or conclusions expressed, arethose of the author alone and do not necessarily reflectHSE policy.