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The Costs of Increasing a Basic Shrimp Vessel from 65 to 85 FEET

A Case Study

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The Task

To investigate the economic sense of increasing the length of vessels designed to prosecute the inshore fishery now being served by a fleet restricted to 65 feet LOA.

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65 Feet And Growing

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Trend Towards Increased Breadth

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

1975 1980 1985 1990 1995 2000

YEAR

LE

NG

TH

/ BR

EA

DT

H R

AT

IO

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Forces Driving Increased Vessel Size

MULTI-SPECIES FISHINGQUALITY IMPROVEMENT THROUGH BOXING AND REFRIGERATED SEAWATERDECK AREA for HANDLING & PROCESSINGCREW ACCOMMODATION

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Vessel Variations

A “TYPICAL” BOAT 65 x 24

INCREASED BREADTH 65 x 30

INCREASED L 75 x 27.5

INCREASED L 85 x 31

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Vessel Variations

ASSUMED CONSTANTS

QUOTASOPERATIONAL SPEEDCREW SIZEBRIDGE AREA

VARIABLE WITH VESSEL SIZE

FISH HOLD CAPACITYDECK AREAACCOMMODATION AREA

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Side Issues – Rules And Regulations

GROSS TONNAGELARGE vs. SMALL F.V. REGULATIONSMANNING REQUIREMENTSLIFE SAVING EQUIPMENTBILGE, BALLAST AND FIRE FIGHTINGSTRUCTURAL FIRE PROTECTION

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Capital Cost Categories

BASIC HULL AND DECK STRUCTURETOPSIDES & OUTFITUNDERWATER EQUIPMENT (STEERING & PROPULSION)

MAIN PROULSION MACHINERYELECTRONICSFISHING GEAR & HYDRAULICSREFRIGERATION & RSW

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CASE STUDY - Independent of Length

OUTFIT LEVELELECTRONICS PACKAGEAUXILIARY MACHINERYFISHING GEAR & HYDRAULICSREFRIGERATION

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CASE STUDY - Principal Variables

HULL AND DECKS STRUCTURE

MAIN PROPULSION MACHINERY

PROPELLER AND SHAFTING

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CASE STUDY - CAPITAL COST BREAKDOWN

TOPSIDES & OUTFITTING

43%

HYDRAULICS/ FISHING GEAR12%

PROP/ STEERING4%

REFRIGERATION2%

PROPULSION MACHINERY

12%

ELECTRONICS 5%

BASIC HULL AND DECKS

22%

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CASE STUDY - Hull and Deck Structure

FRP (Fibre Reinforced Plastic) ConstructionAmerican Bureau of Shipping (ABS) Rules for Building and Classing Reinforced Plastic VesselsLaminate Weight the Basis for Cost Comparison

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CASE STUDY - Capital Cost Comparison

COST CATEGORY 65 BASIS 65 75 85

BASIC HULL AND DECKS $292,875 $343,750 $348,219 $439,313

TOPSIDES & OUTFITTING $542,763 $687,500 $687,500 $687,500

ELECTRONICS $80,000 $80,000 $80,000 $80,000

PROPULSION MACHINERY

PROP/ STEERING

HYDRAULICS/ FISHING GEAR $186,300 $186,300 $186,300 $186,300

REFRIGERATION $30,000 $30,000 $30,000 $30,000

TOTAL CAPITAL COST (MILLIONS)

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THE QUESTION OF POWER

THE BASIS:Determine the required installed power for each vessel

to meet the requirements of:10 knots free running speed and 6 tonnes of tow pull at 2.5 knots

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The Resistance Prediction

Started by generating lines for the four vesselsPredicting resistance for specific vessels 65 x 24 represents where vessels are now75 and 85 vessels are based on this parent hull65 x 30 represents the trend of where design is going

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The Resistance Prediction

No model tests were done The resistance prediction was based on a “standard series” of similar vesselsThe accuracy of the prediction depends on how “similar” the study vessels are to the series vesselsFortunately someone else has done work on short/fat vessels, or “Low L/B Vessels”

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Vessel Parameters

Cb** LWL B T

(ft) (ft) (ft)

1.75 m Draft

65’ x 24’ (Gen) 0.380 0.454 61.385 24.000 5.741 2.558 4.180 3.751

2.0 m Draft

85’ x 31.385’ 0.333 0.441 80.051 31.385 6.562 2.551 4.783 4.018

75’ x 27.692’ 0.354 0.442 70.639 27.692 6.562 2.551 4.220 3.849

65’ x 30’ 0.379 0.515 61.713 30.000 6.562 2.057 4.572 3.262

2.25 m Draft

65’ x 24’ (Gen) 0.379 0.535 61.745 24.000 7.382 2.573 3.251 3.311

2.5 m Draft

85’ x 31.385’ 0.331 0.513 80.623 31.385 8.202 2.569 3.826 3.589

75’ x 27.692’ 0.351 0.515 71.666 27.692 8.202 2.588 3.376 3.464

65’ x 30’ 0.378 0.579 62.087 30.000 8.202 2.070 3.658 2.945

VesselFn @10 knots

L/B B/T L/1/3**

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Series Parameters

Cb L/B B/T

0.447 - 0.631 2.60 - 3.98 2.81 - 4.23 3.01 - 5.30

L/1/3

We had a good basis for predicting the resistance of the 65 x 24, 75 x 27 and 85 x 31 foot vessels

Unfortunately no one has done vessels as “short” and “fat” as the 65 x 30 so these results are a bit suspect

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Effective Power

0

50

100

150

200

250

300

350

400

450

500

2.0 4.0 6.0 8.0 10.0 12.0

Speed (knots)

Eff

ec

tiv

e P

ow

er

(kW

)

65 x 24 65 x 30 75 x 27.7 85 x 31.4

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Summary PE at 10 knots

Effective power for all vessels is essentially the sameAs expected the longer vessels require proportionately less power for the same speedThe power for the 65 x 30 is probably under-predicted

PE

(HP)

65' x 24' 221

65 x 30 A 235

75' x 27.7' 227

85' x 31.4' 244

VESSEL

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Summary PE at 10 knots

The power for the 65 x 30 is probably under-predicted

This was confirmed by Professor Friis based on recently completed model testsWe added a new vessel 65 x 30 A

PE

(HP)

65' x 24' 221

65 x 30 A 353

75' x 27.7' 227

85' x 31.4' 244

VESSEL

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Propulsion

The effective power is simply the power required to push or pull the hull through the water at 10 knots That brings us to the propulsion calculations.

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Free Running Performance

VESSEL PROP EFFICIENCY PD (HP) PB Brake Horsepower

65 x 24 0.594 399 420

65 x 30A 0.548 649 683

75 x 27.7 0.637 360 379

85 x 31.4 0.640 384 404

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Towing Performance

Towline pull is a function of the prop, not the shipA bigger prop is better

VESSEL PROP EFFICIENCY PD (HP) PB Brake Horsepower

65 x 24 0.166 470 494

65 x 30A 0.166 470 494

75 x 27.7 0.193 409 430

85 x 31.4 0.202 388 408

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Propulsion

The best combination of propeller pitch and RPM for free running is NOT the best for the trawling condition and vis a versaThere must be a compromise between free running efficiency and tow pull Installed power will be greater than for ideal conditionThe final outcome is that the same engine choice is made for the 75 and 85 foot vessels

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CASE STUDY - Capital Cost Comparison

COST CATEGORY 65 BASIS 65 75 85

BASIC HULL AND DECKS $292,875 $343,750 $348,219 $439,313

TOPSIDES & OUTFITTING $542,763 $687,500 $687,500 $687,500

ELECTRONICS $80,000 $80,000 $80,000 $80,000

PROPULSION MACHINERY $135,000 $181,000 $135,000 $135,000

PROP/ STEERING $57,500 $57,500 $65,201 $70,196

HYDRAULICS/ FISHING GEAR $186,300 $186,300 $186,300 $186,300

REFRIGERATION $30,000 $30,000 $30,000 $30,000

TOTAL CAPITAL COST (MILLIONS) $1.324 $1.566 $1.532 $1.628

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Life Cycle Costing Model

Capital InvestmentFuelInsuranceVessel Maintenance

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CASE STUDY - Operating Profile

Fishing between April and November

SHRIMP:12 TRIPS - 200 NM

OFFSHORE– To/from grounds @ 10

knots– 48 Hours Trawling @ 2.5

knots

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Life Cycle Costing Model

BASESCAPITAL INVESTMENT – 15 YEARS @ 8%ANNUAL FUEL – TRIP PROFILE and SPECIFIC FUEL CONSUMPTIONINSURANCE - $31.00 per $1000 VESSEL COSTMAINTENANCE – HULL SURFACE AREA

VESSELCAPITAL

INVESTMENTANNUAL FUEL

ANNUAL INSURANCE

ANNUAL MAINTENANCE

TOTAL

65 x 24 $154,680 $22,700 $41,050 $42,500 $260,930

65 x 30A $182,960 $29,600 $48,550 $45,000 $306,110

75 x 27.7 $179,008 $21,800 $47,500 $45,000 $293,308

85 x 31.4 $190,235 $20,800 $50,500 $55,000 $316,535

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Conclusions

Capital Cost Differences TrivialCapital Cost increases are Offset by Fuel SavingsTotal Yearly Costs Differences are only +/- 3%Opportunity to Improve Design Fundamentals

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Conclusions - Intuitive

Longer, more slender vessels require less power than short fat ones at the same design speed – or there is an opportunity to take advantage of greater speeds with similar powerImproved free running performance in a seaway in the longer vessels due to improved pitch performance Improved towing performance in a seaway in the longer vessels due to improved pitch performance Better directional stability and therefore safety in a seawayImproved operability or “working” time for the longer vessels due to improved motionsOpportunity for improved layout on deck and below