single pull macgregor type hatch cover

i

SINGLE PULL MACGREGOR TYPE HATCH

COVER

A PROJECT REPORT

Submitted by

MANU SHARMA

MUHAMMED ASIM M T

NASIR ALI

NIRAJ KUMAR

NITHIN GOPAL

NITHIN XAVIER

In partial fulfilment for the award of the degree

of

BACHELOR OF TECHNOLOGY

IN

MARINE ENGINEERING

K M SCHOOL OF MARINE ENGINEERING

COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY

COCHIN-682022

JULY 2011

ii

CERTIFICATE

This is to certify that the seminar project entitled “SINGLE PULL

MACGREGOR TYPE HATCH COVER” submitted by MANU SHARMA,

NASIR ALI, MUHAMMED ASIM M T, NIRAJ KUMAR, NITHIN

GOPAL S A, NITHIN XAVIER to the department of Kunjali Marakkar School

of Marine Engineering towards the partial fulfilment of the requirements for the

VIII semester of the B.Tech Degree course in Marine Engineering of Cochin

University of Science and Technology, is a bonafide record of work carried out

by him.

Head of the Department Project guide

K M School of Marine Engineering Prof. Dr. Sasikumar P.V.

Cochin University of Science and Technology

iii

ACKNOWLEDGEMENT

First of all we helmed in all humbleness and gracefulness to acknowledge our depth

regards to all who helped team to put this topic, well above the level of simplicity

and into something concrete.

We express our deep sense of gratitude to Director Prof K.A Simon for providing

necessary facilities.

We are very thankful to our project guide Prof. Dr.Sasikumar P.V who was always

there to show us the right track when team needed the help and guided us in

different matters regarding to project. He gave us moral support and guide in

different matters regarding to project report and presentation and is very kind and

patient while suggesting us the outline and structure of project report. .

We are equally thankful to our project coordinator Prof. N.G. Nair for his valuable

help.

We record our sincere thanks to course coordinator Prof. Roy.V.Paul for his

valuable suggestion

Last but not least, we would like to thank our parents and friends and all others who

helped us a lot in gathering different information, collecting data and guided us

from time to time in making the project despite of their busy schedule.

iv

ABSTRACT

Hatch covers are used to cover and protect the cargo in the cargo spaces. Hatch

covers close off the hatch opening and makes it water tight. In the days of wooden

ships, the hatch covers were made of wooden planks, beams and boards and were

covered with tarpaulins. Wooden hatch covers had many drawbacks. Mainly, they

used to get spoilt due to continuous exposure to the moisture laden sea winds. Rain

and sea water also used to produce detrimental effects on the wooden hatch covers.

But with the advent of steel, the wooden hatch covers started disappearing.

Nowadays, mostly steel hatch covers are used. The most common type of hatch

cover used today consists of a number of steel covers linked together. The design of

a hatch cover changes according to the size and design of the ship, but most of the

designs are made to make the opening and closing of the covers as quick as possible

in order to facilitate faster cargo handling process.

One such type of hatch cover is a MacGregor, single pull hatch cover. In

this type, the hatch cover moves on rollers attached to tracks fixed on the hatch

coaming. The hatch cover is not one steel structure but a series of steel covers

linked together by chains. When the cover is opened, the individual steel covers

ride up and tip onto a stowage tank at the hatch end. Most of the hatch covers

found on board ships are controlled hydraulically by a hydraulic power unit

operated from a control box fixed near the hatch cover. .

v

TABLE OF CONTENTS

Page no.

CERTIFICATE ii

ACKNOWLEDGEMENT iii

ABSTRACT iv

TABLE OF CONTENTS v

LIST OF FIGURES ix

LIST OF TABLES xii

CHAPTER 1 - INTRODUCTION 1

1.1 Hatch Cover and Their Function. 2

1.2 Early Hatch Cover. 3

1.3 Failing of Wooden Hatches. 5

1.3.1 Safety and Security 5

1.3.2 Maintenance 6

1.3.3 Cargo Working 6

1.4 Steel Hatches After 1927 6

CHAPTER 2 - TYPES OF STEEL HATCH COVERS 9

2.1 Single Pull. 11

2.2 Side Rolling. 12

2.3 Folding and Multi Type 13

2.4 Lift Away 14

2.5 Piggy Back. 15

2.6 Stacking Covers 16

2.7 Reefers Hatch Covers. 17

2.8 Spring Loaded Covers. 18

CHAPTER 3 - GENERAL REQUIREMENT 19

3.1 Regulatory Requirements. 19

3.1.1 Rule Governing Access Equipment 19

3.1.2 International Load Line Convention, 1966. 19

3.1.3 Freeboard. 20

3.1.4 Freeboard Deck. 21

3.1.5 Weather-Tightness and Water-Tightness. 22

vi

3.1.6 Statutory Regulations. 23

3.2 General Considerations for Access Equipment. 23

3.2.1 Coaming Height 23

3.2.2 Cover Stowage 25

3.2.3 Deck Opening 25

3.2.4 Drainage 26

3.3 Specific Design Requirements for Hatch Covers. 27

3.3.1 Hatch Covers 27

3.3.1.1 Structural Regulations. 27

3.3.1.2 Cleats. 29

3.3.1.3 Loads. 30

3.3.1.4 Scantling. 30

3.3.1.5 Deformation. 31

3.3.2 Seals 34

3.3.2.1 Gaskets Material 35

3.3.2.2 Compression Bar. 35

3.4 Construction Materials. 35

3.4.1 Higher Tensile Steel (HTS) 36

3.4.2 Aluminium 36

3.4.3 Glass Reinforced Plastic (GRP) 37

3.4.4 Wood 37

CHAPTER 4 - OPERATIONAL AND SAFETY ASPECTS 38

4.1 Basic Advice 38

4.2 Monitoring and Inspection 40

4.3 Heavy Weather Precaution 42

4.4 Safety when Working with Hatch Covers 43

4.5 Procedure to Open and Close Hatch Covers 48

4.6 Maintenance and Repair 50

CHAPTER 5 - SINGLE PULL MACGREGOR TYPE HATCH COVER

DESIGN 54

5.1 Parts Design 56

5.1.1 Hold Design. 56

5.1.2 Hatch Opening Dimensions. 56

5.1.3 Hatch Coaming Design. 57

vii

5.1.4 Hatch Covers Design. 58

5.1.5 Track 1 Design. 59

5.1.6 Rising Track Design (Track 2). 60

5.1.7 Jack Design. 60

5.1.8 Crane Space Design 61

5.1.9 Motor Casing 61

5.1.10 Motor Specifications 62

5.1.11 Pulley Design 62

5.1.12 Rope 63

5.1.13 Reduction Gear Design 63

5.1.14 Ladder Design 63

5.1.15 Bulwark Design 64

5.2 Material Selection 65

CHAPTER 6 - FABRICATION 67

6.1 Fabrication of Cargo Hold 67

6.2 Fabrication of Hatch Way 68

6.3 Hatch Coaming Fabrication 69

6.4 Hatch Stay Fabrication 70

6.5 Fabrication of Side & End Dog 70

6.6 Fabrication of Hatch Cover. 71

6.7 Sliding Track Fabrication. 73

6.8 Fabrication of Rising Track. 75

6.9 Fabrication of Crane Space 76

6.10 Motor Reduction Gear Pulley Fabrication 77

6.11 Fabrication of Bulwark 77

6.12 Fabrication of Ladder 78

CHAPTER 7 - ASSEMBLY OF FABRICATED PARTS 79

7.1 Assembly Between Cargo Hold and Hatch Coaming 80

7.2 Assembly of Hatch Stay on Coaming 80

7.3 Assembly of Side Dogs and End Dogs on Coaming 81

7.4 Assembly of Sliding Tracks 82

7.5 Assembly of Rising Track 82

7.6 Assembly of Hatch Cover 83

7.7 Assembly of Crane Space into Cargo Hold. 84

viii

7.8 Assembly of Motor Pulley Gear Arrangement into Cargo Hold 84

7.9 Assembly of Bulwark 84

7.10 Assembly of Ladder 85

7.11 Assembly of Locking Arrangement 86

7.12 Assembly of Wire Rope 86

CHAPTER 8 - TESTS AND TRIALS 88

8.1 Water Hose Leak Detection Test 88

8.2 Ultrasonic Leak Detection Test 88

8.3 Putty or Moulding Clay Test 89

8.4 Chalk Test 89

8.5 Tolerance Test for Hatch Covers 89

8.6 Results 90

CHAPTER 9 - CONCLUSION 91

REFERENCES 92

ix

LIST OF FIGURES

Figure no: Title Page no:

Figure 1.1 Simplified arrangement of a traditional hatch 4

Figure 1.2 Arrangement of an early Mege folding steel hatch cover 8

Figure 2.1 Single Pull Hatch Cover 11

Figure 2.2 Side Rolling 12

Figure 2.3 Folding and Multi –type 13

Figure 2.4 Lift Away 14

Figure 2.5 Piggy Back 15

Figure 2.6 Stacking Covers 16

Figure 2.7 Reefers Hatch Cover 17

Figure 2.8 Spring Loaded Cover 18

Figure 3.1 Deck Opening with Coaming 26

Figure 3.2 Beam is treated as a Uniformly Loaded simply

Supported Structure 27

Figure 3.3 Detailed Analysis of the Structure of a 20,000 tdw

bulk carrier 32

Figure 3.4 Hydrostatic Pressure 33

Figure 3.5 Torsional Distortion of Hatch Ways 34

Figure 4.1 Hatch Panel 40

Figure 4.2 Vessels in Rough Weather 43

Figure 4.3 Check the Lock-Back Mechanism 44

Figure 4.4 Do Not Use Damaged or Unsecured ladders 44

Figure 4.5 Never Smoke in a Hold 45

Figure 4.6 Never Climbs On Top Of Bulk Cargo Without A Lifeline. 45

Figure 4.7 Never Carry Tools or Equipments While Descending or 46

Ascending a Ladder

Figure 4.8 Never stand on the coaming top when the hatch covers are open 46

Figure 4.9 Always wear protective headgear when working. 47

Figure 4.10 Inspect wire 47

Figure 4.11 Always takes precautions when fumigating. 48

x

Figure 5.1 Single Pull MacGregor Type Hatch Cover 54

Figure 5.2 Hold Design 56

Figure 5.3 Hatch Opening Dimensions 57

Figure 5.4 Hatch Coaming Design 57

Figure 5.5 Hatch Cover Design 58

Figure 5.6 Track Design 59

Figure 5.7 Rising Track Design 60

Figure 5.8 Jack Design 60

Figure 5.9 Crane Space Design 61

Figure 5.10 Ladder Design 64

Figure 5.11 Bulwark Design 64

Figure 6.1 Cargo hold 67

Figure 6.2 Hatch way 68

Figure 6.3 Hatch Coaming 69

Figure 6.4 Hatch Stay 70

Figure 6.5 Side and End Dog 71

Figure 6.6 Pantoons 72

Figure 6.7 Pantoons and wheels 73

Figure 6.8 Metallic Wheels on A Pantoon 73

Figure 6.9 Sliding Track 74

Figure 6.10 Hydraulic Jack and Sliding Track 74

Figure 6.11 Rising Track 75

Figure 6.12 Crane Space 77

Figure 6.13 Bulwark 78

Figure 6.14 Ladder 78

Figure7.1 Assembly of fabricated parts 79

Figure7.2 Cargo hold and Hatch coaming 80

Figure7.3 Hatch stay on coaming 81

Figure7.4 Side dogs and end dogs on coaming 81

Figure7.5 Sliding track 82

Figure7.6 Rising track 82

Figure 7.7 Hatch covers 83

Figure7.8 Hatch covers 83

Figure7.9 Cargo spaces into cargo hold 84

xi

Figure7.10 Bulwark 84

Figure7.11 Bulwark 85

Figure7.12 Ladder 85

Figure7.13 Locking arrangement 86

Figure7.14 Wire rope 86

xii

LIST OF TABLES

Table no: Title Page no:

Table 2.1 Operating mode of hatch cover types 9

Table 2.2 summarizes the most important characteristics of 10

each major type

Table 3.1 Freeboard for different ships length 20

Table 3.2 Increase in freeboard 21

Table 3.3 Summary of 1966 Load Line Convention hatch 28

Cover regulation

Table 3.4 Access equipment strength calculations 31

1

CHAPTER 1 - INTRODUCTION

The classic modern hatch cover is the ‘single pull’ which remains the most

common of the all the various forms now in service and may rightly be described

as the natural successor to traditional beams and boards. This cover derives its

name from its immediate predecessor, the ‘multi-pull’ cover, which consisted of a

series of individual panels similar to those of the single pull, but unconnected.

Each panel had to be rigged before being pulled one at a time into stowage.

The complete cover consists of a number of narrow panels which span the

hatchway and are linked together by chains. In the closed position, the panel sides

sit firmly which takes the weight of the cover. Rubber gasket was attached to the

side and end dogs over which weight of panel comes forming a watertight seal.

Extending from the side coamings at the end of the hatchway where the covers

are stowed are steel rails which the individual hatch panels to be transferred to

their stowage location when the hatch is opened.

To open a hatch hold cover, the securing cleats are first freed and each

panel is raised onto its wheel by portable jacks. Entire cover is free to move in a

fore and aft direction with its wheel rolling between guides on the top of the

coaming. It is set in motion by means of a wire (sometimes called a bull wire) led

from a motor wheel and attached to the centre of the furthest edge of the leading

panel i.e. the panel which goes into stowage first and comes out of stowage last.

As the wire is tightened, the panels are each pushed beyond the end coaming. On

reaching the end of the hatchway; the weight of each panel is transferred from its

wheels to balancing rollers situated near its mid length which engage with the rail

extensions of the side coaming. The centre of gravity of each panel is slightly

towards the stowage end of the panel from the rollers so that once the panel is

supported from them, it tips into vertical position. It is then pushed further

towards the end of the stowage space by the next panel to arrive at the hatchway

end. When the hatch is completely open, each panel stands vertically in the

stowage space, and all are kept in place with retaining chains.

To close a single pull cover, the direction of rotation of motor is reversed.

This cause the first panel to leaves its stowage position, its tip through 90 degree

2

about its roller to land horizontally with its wheels resting on the coaming. It is

then pulled further over the hatchway and the chain linking it to the next panel

becomes taut with the result it too is set in motion.

On reaching the end of the stowage space, the second panel tips lie

horizontally on the coaming behind the first and together they pull across the

hatchway. The process is repeated with the third and fourth panels, ending only

when all are lying flat on the coamings and the hatch is completely covered.

1.1 HATCH COVERS AND THEIR FUNCTION

The purpose and function of a hatch cover and its coamings is to prevent ingress

of water into a cargo hold after a large opening has been cut in the deck for cargo

access. Hatch covers are a moveable structure designed to a weather tight

standard.

1.1.1 Hatch Cover Construction

Typically hatch covers are lightweight steel grillages. Modern design methods

using finite element technology enable more efficient material distribution which

results in lighter (thinner) structures.

Construction from high tensile steel results in even thinner plate being

used. For this reason these lightweight structures must be ‘handled with care’.

Prevention of corrosion is essential – safety margins are finite.

1.1.2 Hatch Cover Function

Hatch covers provide a primary structural and weather tight barrier to prevent

water ingress into cargo holds. Rigorous inspection, regular maintenance and

prompt repair of damaged covers, securing’s and supports are essential to

maintain fitness for purpose and, in particular:-

To maintain sufficient strength to resist green seas landing on hatches in

extreme weather;

To maintain a barrier against ingress of water during normal seagoing

weather conditions.

Failure to maintain hatch covers correctly can lead to physical loss of a

cover in extreme weather and hold flooding and possible foundering. Minor

3

leakage can cause cargo damage and, if over a prolonged period, damage to the

ship’s internal structure. Long-term structural decline can lead to structural

collapse and total loss.

1.2 EARLY HATCH COVERS

The upper deck hatches of early steamships, in common with those of sailing

ships, were small by present standards: four meters by two would not have been

untypical hatchway dimensions, even for ocean going vessels in the mid-19th

century. Deck openings were bounded by vertical coamings and spanned by

wooden boards usually laid athwart ships: water tightness was maintained by

tarpaulins spread over the boards and secured by wedges and cleats at the

coamings, an arrangement which had then been in use for centuries. Web beams

were sometimes placed across the largest hatchways but it was not until 1879 that

their use became mandatory for all vessels classed with Lloyd’s Register of

Shipping having hatchways more than 12 feet long. Coamings were required to be

of iron constructions. No minimum height was specified and it was not until forty

years later that they appeared in Lloyd’s Rules. Hatch boards were made of solid

woods 63 mm thick and of such an overall size that they could be handled

manually. Since they were laid transversely across the hatchway it was necessary

to use ‘fore and afters’ to reduce their unsupported span. These were the heavy

baulks of timber placed longitudinally across the hatchway, on the top of the

transverse iron beams and supported at each end by brackets attached to the

coamings. The hatch boards, in turn, were placed across the fore and after which

were so spaced that the unsupported span of the boards did not exceed the

maximum allowed.

After the turn of the 20th

century, the practice of arranging hatch boards

longitudinally began to be adopted. There were sound reasons for this change. A

typical cargo ship hatch,7.5m(25 ft) long and 5 m(16 ft) wide, with athwart ship

hatch boards, would have been fitted with two transverse web beams and three

fore afters which, because of their overall length would each have been made up

in three pieces, one for every beam space as shown in figure 1.1. With

longitudinal hatch boards the same hatch would have required no more than four

transverse beams space 1.5 m apart each of lighter construction than the two webs

4

in previous arrangement. Thus the number of heavy components to be lifted

every time the hatch was opened and closed would have been reduced from

eleven to four.

Figure 1.1 Simplified arrangement of a traditional hatch

Source: Cargo Access Equipment for Merchant Ships.

This arrangement also had the advantage of being safer than the earlier

one. As hatches became longer it becomes increasingly necessary to fit force and

afters in several actions. These were more difficult to ship when battening down

that those modes in one piece, since at least one end of each section had to be

positioned on a seat attached to a traverse web before the hatch board could be

put on. This meant that the man had to sit astride the web, over the open hold, to

guide into place a very dangerous practice.

Atharwdship hatch boards and fore and afters continued to be used well

into 20th

century although the longitudinal arrangement gradually replaced them.

After the implantation of the 1930 international load line conventions fore and

after were only found in ships with very small hatches.

5

All types of wooden hatch were made watertight by means of tarpaulins

and this method is still employed in those ships with traditional hatches that

remain in service. The use of wooden hatch cover has declined throughout much

of this century to the extent that it is now almost unthinkable that they should be

fitted in modern vessel of any size. It is interesting therefore, to consider the

reason for their demise. These fall into three broad categories, namely safety and

security, cargo working and maintenance.

1.3 FAILINGS OF WOODEN HATCHES

1.3.1 Safety and Security

It is impossible to exaggerate the importance and secure hatch covers; there can be

no question that a ship’s survival may depend upon having them. But how

efficient are wooden hatch covers?

Tarpaulins are the most vulnerable component of traditional hatch covers.

There are several common reasons for tarpaulin failure. Slackening of wedges is

one of the most important factor. Chaffing is another serious source of weakness,

especially at the coamings. Tarpaulins are also liable to suffer damage every time

that they are removed for working cargo.

Security of the wooden hatches also arose as a result of the comparatively

large size of the hatchways of many of the ships, especially colliers, then entering

service. Not only were the hatchways longer and wider than had been the customs

up to that time, but the ratio of hatch width to overall beam was often greater too.

This was particularly apparent in ships employed in the carriage of bulk cargoes

and some of the most extreme examples were to be amongst self-trimming

colliers where hatch width/ship beam ratios often exceed 0.6.

Individual hatch boards were laid loosely on top of the beams in a normal

hatchway and they could easily be shipped accidently. In order to prevent this,

interlocking boards were developed. These could be handled manually in the

usual manner but once landed on the beams; they were retained in place by a

simple locking device which was claimed by its manufacturer to enhance the

safety of a ship, should it lose its tarpaulins, by preventing the boards from being

washed away by the sea.

6

1.3.2 Maintenance

The maintenance of the wooden hatches is expensive in both labour and materials.

Although individual components were simple and inexpensive, there were so

many of them in a typical hatch and they were so easily damaged through

continued hard use that the total cost of replacement so often substantial. Wedges

which are vital to the security of the hatches were individually very cheap but they

were frequently lost or misused.

Hatch boards too had to be replaced frequently. Tarpaulins used for

traditional hatches were easily chafed and in some ships one man could well have

been employed continuously for their repair.

1.3.3 Cargo Working

Time spent in port affects the overall economics of operating ships. Attention was

given for higher cargo handling rates and faster turnaround times, and time spent

for opening and closing hatches. This become increasingly apparent as hatchways

became larger. Every hatch component had to be handled separately; tarpaulins

had to be folded back, each hatch board had to be removed manually, each beam

had to be lifted from its seat by derrick and winch or shore crane, and the larger

the hatchway, the more items there were to be handled.

1.4 STEEL HATCHES AFTER 1927

The earliest satisfactory hatch cover produced by the brothers Joseph and Robert

MacGregor, two naval architects from Tyneside, was of the hinged type. It

consists to two large steel slabs, each spanning half the hatchway and hinged at

the side coamings. When opened by winch and derrick, the slabs rotated through

180 degree so that they rested on the bulwarks to form a convenient platform for

working cargo (although obstructing the gangway along the deck). Like other slab

hatches they were kept secure and watertight in the conventional manner and their

hinges were cunningly built into the coamings so as not to impair the

effectiveness of their tarpaulins. However, it was the announcement in 1928 of a

horizontal rolling cover which did not require tarpaulins that marked the real

beginning of the long association of the Macgregor name with steel hatch covers,

which continues to this day.

7

The first horizontal rolling built to the design patented by MacGregor &

king Ltd. Was installed over the aftermost hatchway of the 9000tdw motor ship

sheaf holme which left the Sunderland yard of her builder, Wm. Pickersgill, in

August1929 amid rather more publicity than she would otherwise have merited.

The event was important because it was not the first time that a hatch cover had

been put into service that was easily operated manually, yet depended on

tarpaulins for water tightness nor did it forgo any of the strength with which

previous steel covers had been endowed.

The earliest horizontal rolling covers produced by Macgregor and king

(subsequently known as Macanking) came in two forms, although both were

basically similar. The first was fitted in fairly small hatchways and consists of two

moveable sections fabricated out of steel plate stiffened by channels bars or bulbs

angles, with a skirt around their perimeters which rested on the coaming when the

cover was closed. They revolved about eccentric bushes which could be rotated so

that the clear height of the lower edge of the cover above the coaming could be

varied.

In the closed position, with the hatch secured for sea, the bushes were

aligned so that the perimeter of the cover rested on the coaming throughout its

entire length. To open the hatch, the bushes were rotated through half a turn with

a marlin spike, thus raising the cover so that it could be easily pulled along on its

wheels. This arrangement has become a feature of many MacGregor hatches

since.

In France in 1934, Captain Mege, of Louis Dreyfus Cie, patented folding

steel hatch covers which were first fitted in the cargo ship Louis L.D. two years

later. They considered of double panels hinged together and to the end coamings,

but, unlike the von Tell covers, they were opened by lifting the panel nearer the

coaming hinge. As it was raised, the second panel was pulled towards the end of

the hatchway, supported on two trailing wheels which ran along the coaming,

until both panels were stowed together vertically. In this way a folding hatch

cover could be opened in one operation instead of two. Fig 1.2 shows an early

Mege folding steel hatch cover. Closing was carried out by simply allowing the

fold hinge to open under the combined weight of the two panels until both were

in position resting flat on coaming to which they were secured by bolts. In long

8

hatchways, Mege covers were fitted to both end coamings. The folding principle

that was incorporated into their design has become widely adopted, for both wire

operated and hydraulically operated folding covers. More than thirty ships were

fitted with Mege covers before MacGregor & Co. Became the sole licensee for

their construction in 1949.

Figure 1.2 Arrangement of an early Mege folding steel hatch cover


9

CHAPTER 2 - TYPES OF HATCH COVERS

Many types of hatch cover are now available and the principal ones are listed in the

below table where they grouped according to their mode of operation. Table 2.2

shows the most important characteristics of each major types.

Table 2.1 Operating mode of hatch cover types


Rollin and tripping Single pull

Lifting Pontoon Rolling End rolling

Side rolling Lift and roll(piggy-back) Telescopic

Roll stowing Roll stowing(rolltite) Flexible rolling

Folding Hydraulic folding Wire operated folding Direct pull

Sliding/nesting Tween-deck sliding

10

Table 2.2 Summarizes the most important characteristics of each major type

NNo Cover type Usual ship types

Decks applicable

Approximate %of covers fitted to recent new ships

Guide to minimum coaming height

Drive system

Cleating system

1 Single pull (D) Weather 41 Depends on section lengths but more than(A)

Electric, hydraulic or ship’s cargo gear

(E)

2 Hydraulic folding

(D) Weather/Tween 25 (A),(B) or(C)

Hydraulic (E)

3 Wire-operated folding

(D) Weather/Tween 10 (A),(B) or(C)

Winch Screw or quick-acting

4 Direct pull All ships with cargo gear

Weather 3 (A) Or(B) Ship crane or derrick

Autom-atic

5.

Roll stowing

(D) Weather 2 Depends on drum diameter but usually more than (A) or(B)

Electric or hydraulic

(E)

6 Side and end rolling

All, but mainly large bulkers and OBOs

Weather 4 (A) or (B) Electric or hydraulic

(E)

7 Lift and roll All, but mainly bunkers

Weather 2 (A) or (B) Electric or hydraulic

(E)

8 Tween-deck sliding

Multi-deck cargo ships

Tween and Car decks

2 (C ) Electric Token

9 Pontoon (F)

Container ships, Multi-deck cargo ships

Weather/Tween 11 (A), (B) or (C)

Ship or shore crane

(E)


11

2.1 SINGLE PULL

Figure 2.1 single pull hatch cover

Source: - Walter Vervloesem – IMCS

2.1.1 Description

The classic modern hatch cover is the ‘single pull’ which remains the most common

of the all the various forms now in service and may rightly be described as the natural

successor to traditional beams and boards. This cover derives its name from its

immediate predecessor, the ‘multi-pull’ cover, which consisted of a series of

individual panels similar to those of the single pull, but unconnected. Each panel had

to be rigged before being pulled one at a time into stowage.

The complete cover consists of a number of narrow panels which span the

hatchway and are linked together by chains. In the closed position, the panel sides sit

firmly which takes the weight of the cover. Just inside the side plate is a rubber gasket

attached to the cover, which rest on a steel compression bar forming a watertight seal.

Extending from the side coamings at the end of the hatchway where the covers are

stowed are steel rails which the individual hatch panels to be transferred to their

stowage location when the hatch is opened. Although single pull covers rarely exceed

16 m in width, larger sizes can be manufactured.

12

2.2 SIDE ROLLING

Figure 2.2 side rolling hatch cover

Source: - Walter Vervloesem - IMCS

2.2.1 Description

Rolling covers usually consist of two large panels at each hatchway. They are fitted

with wheels which roll along a track at both sides of the coaming top. Stowage rails,

which may be portable, extend this track via pillars welded to the deck. In some

installation, the wheels are not attached to the hatch cover but to the coaming and to

fixed pillars on the deck, and the cover rolls across them. Apart from stowage

location, the principal difference between side end rolling covers is that the joint in

between side rolling panels is longitudinally and between end rolling panels is

athwatships.

These covers are usually fitted to large ships. They are often extremely heavy

owing to their large dimensions and require hydraulic pot lifts (rams) to raise them

into the rolling position. These hydraulic lifts are fitted to the coaming below the

wheels (in their closed position) and are illustrated in fig. There is no limit to the size

of the covers, and panels 20 metres square (20 m*20 m) have been installed in ships.

13

2.3 FOLDING & MULTI-TYPE

Figure 2.3 folding type hatch cover


2.3.1 Description

Folding covers may be fitted at both weather deck and tween deck hatchways. In its

simplest form, this type of hatch cover consists of two flat topped panels, similar in

basic construction to those of the single pull system. Complex configuration may have

three or more panels at each end of the hatchway, although installations with an

uneven number of panels are rare. Wire-operated covers having more than two panels

require special rigging and their operation is therefore slow.

A typical hydraulic operated cover is shown below. Adjacent panels are

hinged together so that they can fold as shown. The panel at the stowage end is hinged

to a plinth welded to the deck and hydraulic rams are usually arranged as illustrated.

The ram rod is withdrawn into the cylinder to prevent corrosion when the hatch is

closed at sea. Covers up to 26 m wide have been installed in ships.

14

2.4 LIFT AWAY

Figure 2.4 Lift away type covers


2.4.1 Description

Lift-away hatch covers for use on the weather deck are divided into two

categories as follows: .

SINGLE-PANEL COVERS: MULTI-PANEL COVERS:

single-opening abreast with longitudinal joints .

multi-opening abreast with transverse joints .

Single-Panel types comprise one cover for each opening i.e. there are no joints. They

are normally specified for bulk carriers in the case of single opening abreast, and for

cellular containerships in the case of multi-opening abreast configurations.

Multi-Panel covers comprise several separate panels for each hatch opening.

They are used for cellular containerships in the case of longitudinal joints, and for

multipurpose cargo ships and heavy cargo tonnage in the case of transversal joints

15

2.5 PIGGY BACK

Figure 2.5 Piggy type


2.5.1 Description

Lift and roll covers are a development of rolling covers and example is illustrated in

fig. Each covers consists of two panels, one of which has powered wheels. In the way

of the ‘dumb’ panel, four hydraulic rams which act vertically upwards are fitted with

the coaming. These engage in lugs on the side of the panel to lift it high enough above

the coaming for the motorized panel to roll underneath. The dumb panel is then

lowered onto the motorized panel so that both can be moved together. The side

coaming can be extended so that the two panels can be stowed beyond the hatch end.

Alternatively these covers can be side rolling, stowing abreast the hatchway. There is

in the theory no limit to the size of these covers composed of two 100-tonne panels

for 26m by 23m hatch ways have been supplied for forest product carriers.

16

2.6 STACKING COVERS

Figure 2.6 Stacking type covers


17

2.7 REEFERS HATCH COVERS

Figure 2.7 Reefers hatch covers


18

2.8 SPRING LOADED COVERS

Figure 2.8 Spring loaded covers


19

CHAPTER 3 - GENERAL REQUIREMENTS

3.1 REGULATORY REQUIREMENTS

3.1.1 Rules Governing Cargo Access Equipment

Cargo ships exist to transport goods from one port to another to accomplish this; they

must have some means of getting cargo into and out of their holds. Thus ships must

have opening either in the weather deck, as in vertically loading vessels, or in the

bow, stern or side, as in horizontally loading vessels. These areas are all vulnerable to

damage at sea. Thus cargo access equipment must provide access in port while

keeping water out, during voyage. One of its prime functions is to ensure the safety of

ship, personnel and cargo. In order to maintain acceptable standards of safety at sea,

rules and regulations have been introduced over the years, many of which directly

concern access equipment.

3.1.2 International Load Line Convention, 1966

Probably the most important regulations that affect access equipment are those arising

from the 1966 load line convention which replaces the first international load line

convention in 1930 for determining the freeboard. It provides for two categories. It

provides for two categories of ship for freeboard purpose-Type. A ships which are

those designed to carry liquid cargoes in bulk and whose tanks have small access

openings and Type B which includes all other ships. Among Type B ships are certain

bulk carriers and ore carriers which are further sub-divided as follows:

(a) Ships of over 100 m length having steel hatch cover on all exposed hatchways

and which can remain afloat in satisfactory equilibrium with any one

compartment flooded. When the length exceeds 225 m, the machinery space is

also treated as a floodable compartment. These ships can have table B

freeboards given in table B and A summarized in table; such freeboard is

referred to as B-60.Tables A and B referred to the minimum freeboard laid

down by the Convention for type A and Type b ships.

(b) Ships which can withstand flooding of two adjacent compartments may be

assigned B-100 freeboard, virtually equal to type A ships.

20

Type B ships which are fitted with portable covers, e.g. beams and boards in

position 1 hatchways are required to have their freeboard increased above

those given in table B.

3.1.3 Freeboard

Table 3.1 shows freeboard from the full tables and compares freeboard for different

ships length as required by Load Line Conventions of 1930 and 1966.Corrections are

made to cater for non-standard length depth ratios, block coefficient, extent of

superstructure etc. The standard ratios block coefficient, extent of superstructure etc.

The standards freeboard applies in salt water.

Table 3.1 Freeboard for different ships length

Ship length, metres

Tanker Freeboards 1930, mm

Table ‘A’ Freeboards 1966, mm

Steamer Freeboards 1966 mm

Table ‘B’ Freeboards 1966, mm

30 - 250 250 250

60 570 573 570 573

90 1015 984 1070 1075

120 1550 1459 1775 1690

150 2170 1968 2540 2315

180 2710 2393 3230 2915

210 (3080) 2705 3810 3430

240 (3370) 2946 (4310) 3880

300 (3830) 3262 (4755) 4630


In designated summer zones throughout the world; slightly different values in

winter or tropical zones in fresh water, or when timber deck cargoes are carried, as

laid down and in the corresponding national legislation, in the United Kingdom. The

merchant shipping (Load line) Rules, 1968. It can be seen that increasing maximum

draft and therefore cargo deadweight. Table 3.2 is derived from the full tables and

shows the increase in freeboard required for Type B ships having portable covers

21

secured by tarpaulins and battening devices, e.g. beams and boards .Position 1 hatch

board are defined as those on exposed freeboard decks, raised quarter decks, and

exposed superstructure decks within the forward quarter length of ship, while position

2 hatchways are those on exposed superstructures deck is regarded as the deck

immediately above the freeboard deck.

Table 3.2 Increase in freeboard

Length, metres

Freeboard Increase, mm

Resultant Freeboard, mm

30 50 300

60 50 623

90 50 1125

120 84 1774

150 228 2543

180 313 3228


3.1.4 Freeboard Deck

Regulation 3, paragraph 9 of 1966 LLC defines the freeboard deck and is quoted here

in full as it has an important bearing on all aspects of equipment used for closing

cargo openings.

The freeboard deck is normally the uppermost complete deck exposed to

weather and sea, which has permanent means of closing cargo openings in the side of

the ship are fitted with permanent means of watertight closing. In a ship having a

discontinuous freeboard deck,

The lowest line of exposed deck and the continuation of that line parallel to the

upper part of deck is taken as freeboard deck. At the option of the owner and subject

to the approval of the Administration ,a lower deck may be designated as the

freeboard deck provided as it is complete and permanent deck continuous in a fore

and aft direction at least between the machinery space and peak bulkheads and

continuous athwart ships. When this lower deck is stepped the lowest line of the deck

and the continuation of that line parallel to upper part of the deck and is taken as the

22

freeboard deck. When a lower deck is designated the freeboard deck, the part of hull

which extend above the freeboard deck is treated as superstructure so far as concerns

the application of the conditions of the assignment and the calculation of freeboard. It

is from this deck that the freeboard is calculated.

It should be noted that the requirement for a lower deck to complete and

permanent in order to be designated the freeboard deck, does not mean that any

openings need to be weather tight, only that the structure of a deck is present. Tween-

deck hatches may be of steel or wood, but are only required to be watertight if fitted

to deep tanks or compartments containing water ballast.

The ‘Administrations’ referred to include the Department of Trade in the

United Kingdom, the us coast guard in the united states and equivalent in other

countries.

3.1.5 Weather-Tightness and Water-Tightness

Regulation of the 1966 LLC which covers the mean for securing weather-tightness of

steel weather-tight covers states that ‘The means for securing and maintaining

weather-tightness shall be to the satisfaction of the Administration. The arrangement

shall ensure that the tightness can be maintained ain any sea conditions, and for this

purpose test for tightness shall be required at initial survey ,and may be required at

periodical survey and at annual inspections or at more frequent intervals.

Regulation defines ‘weather-tight’ as meaning that water will not penetrate

into the ship in any conditions. ‘Weather-tight’ is not defined into 1996 LLC but is

generally regarded as higher standard than weather-tight.it is usually taken to require

the closure to be capable of preventing the passage of water through the structure in

any direction, under the head of ships margin line, which is line drawn at least 76 mm

in below the upper surface of bulkhead deck at the side of ship.

In practice the hatch covers of B-60 and B-100 ships must be of steel and

made weather-tight by means of special gasket devices. Less commonly, hatch may

be made weather-tight by means of tarpaulins and battening devices over wooden or

portable steel pontoon covers.

3.1.6 Statutory Regulations

The 1966 load line convention came into force in 1968 after it had been ratified by

required number of maritime nations. In UK the convention was brought into the

23

force by the 1967 Merchant shipping Act from which the merchant shipping (load

line) rules 1968 were made the rules for the constructions of ship laid down by

Lloyds register of shipping are consistent with the convention, as are those of other C

classification societies.

3.2 GENERAL CONSIDERATIONS FOR ACCESS EQUIPMENT

3.2.1 Coaming height

Minimum coaming height, derived from the 1966 LLC, is laid down by Classification

Societies. Height are measured above the upper surface of the deck, and any sheathing

that may be fitted, and for hatchway closed by portable covers secured water tight by

tarpaulins and battening devices, they must not be less than:

600 mm (23.5 in) for Position 1;

450 mm (17.5 in) for Position 2,

Coaming of hatchways closed by steel covers fitted with direct securing

arrangements are usually as indicated above, taking into account any sheer or camber

when assessing minimum height. They may, however, be lower, or even omitted

entirely, if the safety of the ship is not impaired by doing so, provided the

Administration of the country concerned consents.

The scantling and securing arrangements of flush hatch covers or those having

less than standard height coamings are treated as special cases. Such arrangements

have been approved in the past. Dock safety regulations generally require a minimum

coaming height of about 760 mm (2 ft 6 in), otherwise additional fencing must be

fitted to prevent personnel falling through the hatchway.

It is rare for ship to have coamings of lower height than those stipulated,

unless they are completely flush. Flush weather decks are required in a variety of

circumstances. For instance, vehicles, wheeled cargo, or containers must sometime be

stowed over the full deck area including the hatch covers, and clear decks for

recreation are desirable in passenger ships. Satisfying the flood ability requirement for

B-100 and B-60 ships may result in coaming being increased in height on such ships

to meet loadline and subdivision regulation.

24

In practice one of the principal determinants of coaming height is the operation

of the hatch cover. Other types that are affected in this way are rolling stowing covers

where the drum height must be sufficient to allow the stow covers to fit between the

drum axis and the deck and single pull covers whose panels stow in an upright

position standing clear of the deck.

The coaming may also be increased in height to obtain additional cargo

capacity. As a result of these considerations, the majority of the ships have in the

range 1.0-1.8 m. It is useful if crew and stevedores can see readily into the holds

during port operations. Thus if the coaming is higher than about 1.4 m, a step or a

narrow platform should be fitted at the suitable height. While the top of the coaming

is nearly always at the same level on all its sides, it need not be parallel with the deck.

Neither is it essential that the coaming plates be vertical, if by sloping them inwards, a

larger opening at deck level can be obtained.

Another factor influencing coaming height is the nature of particular deck

cargoes. Packaged lumber, for example, is usually stowed abreast hatchways until it

reaches the height of the hatch cover top, when it is distributed over its whole width of

the ship. Lumber is usually banded into packages, each 660 mm high, which are

stowed with a 25 mm batten between them. Coamings should therefore be designed

with a height from deck to hatch cover top which is a multiple of 685 mm (27 in). In

heavy lift cargo liners, the coaming height and bulwark height are often the same so

that awkward loads like barges may be easily supported across the entire ship.

In some ship the internal volume bounded by the coamings needs to be a

greater proportion of the total hold volume than the minimum 600 mm coaming

height allows. In the past certain ships engaged in the grain trade were required to

have coamings enclosing 4 percent of the total hold volume to allow for settling, but

this requirement have now been suppressed by the provisions of the Safety of Life at

Sea Conventions 1974(SOLAS 74). These new provisions do not stipulate a minimum

or maximum coaming volume, although it may be necessary to arrange a coaming

height in excess of 600 mm in a particular ship so as to meet the stability requirements

for the carriage or grain. These assume that the cargo ships in to void spaces below

side decks, so producing a heeling moment which depends on the resulting ‘free

surface’ of the grain.

25

3.2.2 Cover Stowage

Where a designer is attempting to obtain the largest possible hatchway openings, the

question of the hatch cover stowage is especially important. The width of the stowage

space is fixed by the hatchway width if the covers are stowed at the end of the

hatchway, but the height and length of the space can be varied. If the hatchways are to

be the longest possible in a given deck length, the length of the stowage space must be

kept to a minimum; this can be accomplished in a various ways depending on the type

of hatch cover employed. No special stowage space is required for simple pontoon

covers since these are usually stowed on adjacent hatch covers or on the quayside

when the hatch is open. Alternatively side rolling covers may be used if the hatchway

is not too wide in relation to the ships breadth.

3.2.3 Deck Openings

As deck opening becomes larger, the problem of ensuring adequate hull strength

becomes more complex. The necessary longitudinal strength of the hull girder can be

readily achieved, even for ships with hatch widths 80 percent of the breadth of the

ship, by the use of high tensile steels. But the provision of the adequate torsion

strength may require very detailed design and stress analysis, since the torsional

deflection of a ship with large hatchways give rise to high stress concentration at the

corners of the openings and to deformation of the hatchway.

26

Figure 3.1 (a) Rounded deck opening with coaming

(b) Coaming plate following deck opening


To avoid high stress concentration in deck plating, the corners of deck

openings should be elliptical or parabolic. As the corners of the hatch covers are

usually rectangular, provision has to be made to accommodate the hatch coaming.

This can be done in two ways: either a square coaming can be built with the rounded

deck plating protruding into the coaming space shown in fig3.1 (a) and (b) or the

coaming can follow the shape of the deck opening with a filling-in plate welded to its

top. In both cases the clear opening for rectangular cargoes like containers will be

appreciably smaller than the maximum dimensions to the inside of the coamings.

3.2.4 Drainage

As mentioned earlier, an important function of access equipment is to prevent water

entering the ship through the openings in its hull. If the hull is flexing in heavy

weather, it is almost inevitable that some water will penetrate the seals of closing

devices, especially if they are worn. Thus there must be a second line of defence, such

as drains, for removing any water before it can damage the cargo.

Drainage facilities must be built into all terms access equipment. Here water

which seeps past the peripheral seal of a hatch cover runs along a channel and is

discharged onto the weather deck through a hole in the coaming. Where the drain is

below the freeboard deck, as in flush weather deck covers, it must be connected to the

bilge, or overboard via a scupper and non return valve.

27

It is also necessary to provide drainage for the vehicle deck in Ro-Ro vessels.

Any scupper which drains a space within an intact superstructure on the free board

deck (usually the main vehicle deck) is led overboard through a pipe fitted with a

screw-down non return valve having open/shut indicators and capable of being

operated from accessible positions above the freeboard deck. Alternatively the

scupper may be led down to the bilges or to a drain tank. In an enclosed tween deck

space with a continues centre-line casing, additional scuppers must be installed

adjacent to the casing on the main vehicle deck. Where the inboard end of a deck

scupper would be below the load waterline at an angle of heel less than 15 degree, it

should be led to a separate drain tank, which may be pumped overboard.

3.3 SPECIFIC DESIGN REQUIREMENTS FOR HATCH COVERS

3.3.1 Hatch Covers

The hatch cover structure consists in essence of steel beams or grinders spanning the

shorter hatchway dimension, plated over on top completed by steel side and end

plates. The top plate provides the top flange of the beams and grinders. For the

simpler types of hatch cover panel, e.g. pontoon or single pull, the design and analysis

assume a uniformly loaded simply supported beam as shown in the fig 3.2.

Figure 3.2 Beam is treated as a uniformly loaded simply supported structure


3.3.1.1 Structural regulations

The construction of exposed hatch covers is governed by regulations 14 to 16 of the

1966 Load line convention (1966 LLC). Regulation stipulates that exposed coamings

and hatchway covers above the superstructure deck shall comply with the

requirements of the appropriate national administration, which means in effect, that

28

such equipments must be design in accordance with the current practice of the

administration.

Table 3.3 below summarizes the other requirements of these regulations for

beam and board portable covers, and steel pontoon covers secured by tarpaulins and

battening devices, and steel covers fitted with direct securing arrangements. In this

context steel pontoons are plated, covered having interior webs and stiffeners,

extending the full width of the securing arrangements. Classification society rules

embrace these regulations but are more detailed and include non statutory non

exposed cargo covers; they vary slightly between societies. Some important aspects of

hatch cover design are not the concern of the 1966 LLC, such as increase scantling for

special cargo loads.

Table 3.3 Summary of 1966 Load Line Convention hatch cover regulation

Hatch cover types Materials

requirements

Portable covers secured watertight

By tarpaulins and battering devices

Wood board

and mild steel

beams

Steel pontoons

Minimum

thickness of

wooden boards

assumed load

ship length

under 24m ship

length over

100m ship

length 24m-

100m

load factor

maximum

deflection

Assumed load

29

Other steel hatch cover secured weather

tight with gaskets and clamping devices

mild steel

load factor

maximum

deflection

minimum

platethickness

assumed load

load factor

maximum

deflection

minimum plate

thickness

1) With maximum span of 1.5m. thickness increased

proportionately for large spans.

2)Maximum stress to be less than

(minimum ultimate strength of steel)/(load factor)

3)The strength and stiffness of covers

made of materials other than mild steel must

be equivalent to those of mild steel to the satisfaction

of administration


3.3.1.2 Cleats

The 1966 LLC requires that satisfactory means for securing weather tightness be

provided, and gives requirements for covers secured by tarpaulins and battens. For

gasket covers, details are usually agreed between the hatch cover designer and

classification society.

30

An important aspect of the gasket type securing arrangement, whatever its

form is that the pressure between the sealing gaskets and compression bars is correctly

maintained. Manual cleats are often over tightened despite the steel to steel contact of

the cover skirt plates on the coaming bar, with the result that gasket. Life is severely

shortened. This problem is overcome by the introduction of resilient and quick acting

cleats which means that the correct sealing pressure is consistently and uniformly

applied. Cleats on steel covers are generally spaced about 1.5-2 m apart, closer

adjacent to the corners, and no more than 0.6 m apart for wooden covers. With the

advent of larger and heavier hatch covers, the classification societies have, in some

cases, approved covers with greater than usual cleat spacing.

3.3.1.3 Loads

The hatch loading laid down by the 1966 LLC and summarized in table shown take

account of the forces exerted on exposed covers by heavy seas breaking over the deck.

Once again however, these are mandatory minimum values and the classification

societies may require that they are increased in certain cases. Thus for hatch covers on

which deck cargoes are rarely if ever carried, the loading laid down are adequate,

typically 1.75 tonnes/ . This is equivalent to the cargo stowed 2.45 m high at 1.39

/tonnes. Loading for the covers in the foremost quarter of the ship’s length may be

increased to counter the severe sea water forces likely to be experienced in this region.

3.3.1.4 Scantling

Minimum scantling (thickness and dimensions of steel plating and stiffeners) and load

factors for steel covers respecified in the 1966 LLC, so that the load factor multiplied

by the maximum stress in the covers is less than or equal to the minimum ultimate

strength of the steel. Corresponding minimum scantling depending on loading are

given in classification society rules, alternatively direct calculations of required

structural strength may be made using maximum design stress levels.

Table 3.4 below shows the requirements of Lloyd’s Register with respect to

steel hatch covers or other access equipments constructed of grade A mild steel

having a minimum ultimate tensile strength of 4100Kgf cm square.

31

Table 3.4 Access equipment strength calculations

Factor Weather deck Tween-deck

Maximum bending stress,

kgf/cm square

965 1200

Maximum shear stress,

kgf/cm square

700 700

Maximum deflection 0.0028 * span 0.0035*span


The top plate of a typical hatch cover panel may be from 6-13 mm thick

depending on the spacing of the beams (generally, thickness=spacing/100). This plate

is stiffened by beams spanning the hatch cover, usually fabricated ‘tee’ beams having

a depth of about 4 percentage of the span and spaced 500-1000 mm apart. The panel is

completely by side and end plates which may be from 8.20 mm thick.

3.3.1.5 Deformation

As the ship become larger and hatchways take up a greater percentage of the deck

area, so the question of hatchway deformation becomes more important. Traditionally

ships have fairly small hatchways and so have derived a considerable amount of their

strength from their decks. As hatchways have increased in width, so the deck’

contribution to the longitudinal and the torsional strength of the hull girder has

declined, being limited to the strips of deck outboard of the coaming and between the

hatches. A ship with hatchways more than 70 percentage of the beam in width has

approximately half the torsional rigidity of a similar ship with hatchways which are

only 40 percentage of the ship’s beam. Compensation in the form of thickened plating

and/or box girders may be required.

Fig 3.3 indicates the extent of hatchway deformation that may be encountered

in a large bulk carrier loaded in alternate holds. Although the deformation is not

excessively large and is not permanent, they can be sufficient to allow sea water to

enter and parts of the hatch cover to fracture.

32

Figure 3.3 Detailed analysis of the structure of a 120,000 tdw bulk carrier


It has been suggested that, since hatchways are always closed by hatch covers,

the latter ought to be designed to contribute to the strength of the hull girder. This is

however not practical as the devices securing the cover to the coamings would have to

be excessively robust, and any deformation due to the loading of the vessel in port

could lead to the covers becoming jammed and thus impossible to open. Moreover, to

make a significant contribution to vessel’s strength, the covers would have to be

considerably stronger and heavier than at present, and this could introduce operational

difficulties.

Hatch coamings can be designed to contribute to the longitudinal strength of

the ship but there can be problems associated with this. If it is decided to use the

coaming in this way, they must be continuous over the midship portion of the ship and

properly tapered at the forward and after into account in calculating the midship

section modulus, according to classification society requirements.

33

Longitudinal deformation of the top of the coaming is due to the hogging or

sagging of the vessel. It depends on hatchway length and may be as much as 7-8 mm

at each end. Longitudinal deformation is compensated for by fitting at the ends of the

hatch cover with wide gaskets whose rubber absorbs the relative movement of the

compression bars as the sip works. Hatch end cleats must allow such movements,

which would otherwise be taken up at the cross joint with attendant risk of leakage.

Steel to steel contact is must. The purpose of this is to prevent the over compression

of the gaskets. However, it gives rise to a frictional force whose magnitude depends

on the pressure of the cover on the coaming bar and their relative movement.

Transverse deformation is caused mainly due to the vessel’s changes in draft

as cargo is worked, but also by hogging and sagging. Deformation of as much as 15-

25 mm over the width of long hatchways is possible. Relative movement between the

cover and the coaming is allowed for in a similar way to longitudinal deformation, by

providing the cover with wide gaskets, and by ensuring that the wheels on one side of

the hatch cover panels are free to move laterally as shown in fig 3.4

Figure 3.4 Hydrostatic pressure


Torsional deformation is caused by the combination of non symmetrical

loading of the vessel and hydrodynamic forces when the ship heads diagonally into

waves. It can rack the midships hatchway diagonal of a large container ship by as

34

much as 30 mm. Fig 3.5 shows the torsional distortion and the resultant movement

between the hatch cover and coaming. By fitting resilient cleats at the ends of the

hatch covers, some movement between cover and coaming takes place, thus reducing

the relative movement between panels.

Figure 3.5 Torsional distortion of hatch ways


3.3.2 Seals

The 1966 LLC requires cargo access openings to be weather tight which is generally

achieved by an arrangement of sealing gaskets and drainage channels.

The main requirements of sealing system are as follows:

(i) It must prevent any transfer of water from outside the ship to the cargo

space,

(ii) On combination carriers, it must be oil tight to prevent any transfer of

liquid from the inside of a cargo space to the outside, when subjected to

the pressures.

(iii) It must be able to maintain the weather tight integrity of the cargo space in

all sea states and thus, it must be able to accommodate the deformation

discussed earlier.

(iv) It should be resilient and able to accommodate normal irregularities in the

mating surfaces,

(v) The gasket should be abrasion resistant as it may rub against the mating

surface. It must also be resistant to cargo contact,

(vi) It should be easy to maintain,

35

(vii) It should retain all the above properties throughout a long service life,

exposed to climate extremes.

3.3.2.1 Gaskets material

Gaskets material must be of a suitable quality; it should not harden excessively when

subjected to neither sub-zero temperature nor soften in tropical conditions.

Particularly important in this respect are gaskets fitted to refrigerated vessels.

Most gaskets used for seals on dry cargo ships are of natural, synthetic or

neoprene rubber, while combination carriers requires a nitrile composition, resistant to

chemical attack by oil. In general neoprene synthetics have good heat, ageing, weather

and flame resistance, but only moderate oil and chemical resistance but worse cold

temperature properties. General construction of seal steel work, welding and painting

needs careful attention.

3.3.2.2 Compression bars

The usual arrangement of compression bars is shown. It is of rectangular section mild

steel welded to the coaming bar. After several years of service, these bars can become

badly corroded and require replacing. Moreover, they may then have sharp corners

which press into the gaskets so that the rubber takes on a permanent set earlier in its

life than would be the case for a sealing arrangement employing either a round

compression bar, as shown or rectangular one with rounded corners. The latter

produces an element of ‘knife edge’ loading which gives the good seal with the

rubber. When such compression bars are fitted, they are often of stainless steel, which,

although initially expensive, often worthwhile as it is not usually necessary to replace

the bar during the life of the corners

3.4 CONSTRUCTION MATERIALS

In general, Grade A mild steel is used for the construction of all cargo access

equipment. Grade A is the ‘ordinary’ mild steel used for most ship building purposes.

Certain application requires Grades D and E steel. Grade D is notch-tough steel with a

chemical composition largely chosen by the steel producer provided that it retains

good weldability. Grade E steel is the highest grade and is also notch-tough but its

manufacture and composition are strictly controlled. Grades D and E steel are

specified for coaming bars on refrigerated ships where low temperature brittle fracture

36

must be guarded against. As these steels have low corrosion resistances, special

coating, e.g. epoxies, are often used on the underside of hatch covers where sweating

can cause accelerated corrosion. Other materials such as higher tensile steel and

aluminium are acceptable to the Classification Societies.

3.4.1 Higher Tensile Steel (HTS)

If the stress level within a structure were the only factor governing its scantlings, the

use of higher tensile steel instead of mild steel would result in weight savings of up to

15 percent. However stress is not the only governing factor. Deflection, minimum

thickness, ease of construction, initial and maintenance costs must all be taken into

account. Higher tensile steel (HTS) can sometimes be used for the beams of hatch

covers, with their top plates made from mild steel. This reduces the weight of the

covers, without incurring the extra cost of using all HTS construction. Thus, HTS is

sometimes used on hatch covers where, by reducing the cover weight slightly, it may

be possible to install less powerful operating mechanism. Construction entirely in

HTS is sometimes used in pontoon covers for container ships, to keep their weight

below the maximum lifting capacity of container cranes.

3.4.2 Aluminium

Aluminium structures can be 55-60 percent lighter than equivalent mild steel

structures. Most of the problems associated with higher tensile steel are not present

with aluminium. Since it is not as strong as steel, thickness have to be increased,

thereby alleviating problems associated with minimum regulatory deflection, buckling

etc., unless the design is such that deflection is significant. Welding aluminium does

however require special skills and equipment. Corrosion is less of a problem if the

correct grade of material is used and if precaution are taken where steel and

aluminium meet, e.g. at coamings. The spacing of stiffeners can be increased in an

aluminium structures this has the added advantage that the number of stiffeners and

hence the weight and cost of the structure can be further reduced. The major

disadvantage of aluminium is that a suitable grade of material for access equipment

costs approximately eight times as much per tonne as mild steel, with the overall

effect of increasing the cost of the cover by upto three times.

Aluminium covers have been fitted to deep tanks because they are so much

lighter. Since deep tank covers are often made in one piece, aluminium covers are

37

easier to handle without power assistance. Aluminium single pull weather deck covers

have occasionally been fitted in the past, sometimes experimentally. Aluminium can

be used for Ro-Ro vessel access equipment but it is usually limited to small ramps and

car decks. It is less resistant to fire damage than steel.

3.4.3 Glass Reinforced Plastic (GRP)

GRP structures are light but the modulus of elasticity of GRP is only 7 percentages of

that of mid steel and excessive deflection is a problem which invariably accompanies

its use. Additional stiffening is thus necessary, making the structure heavier and more

expensive to manufacturer. For this reason GRP has not as yet found wide application

in the construction of cargo access equipment, although development work is in

progress. GRP in ‘sandwich’ construction could be particularly suitable for covers in

refrigerated ships because insulation can be built into them during the manufacturing

process at very little extra cost, whereas the present system of insulating steel covers

is expensive and time consuming.

3.4.4 Wood

Wooden covers no longer supplied to weather decks of new cargo ships, although on

rare occasions, they are fitted in tween decks. Classification society rules lay down

scantling for beam and boards covers because of LLC requirements; in practice they

care now mainly for the benefit of repair to older ships.

38

CHAPTER 4 - OPERATIONAL AND SAFETY ASPECTS

4.1 BASIC ADVICE

There are procedures which will help to keep ship’s hatch covers in good condition.

The following advice can be considered best practice.

4.1.1 Always

Carry out regular examination of the hatch covers, hatch beams and coamings

to identify:

o General levels of corrosion (check with your classification society for

corrosion allowances);

o localised corrosion at welded connections (grooving);

o Cracks in joints and weld metal;

o Permanent distortion of plating and stiffeners;

Call a Class Surveyor and carry out repairs as soon as possible when there are:

o Indications of excessive corrosion e.g. holes or local buckling of the

top plate;

o Cracks in main structural joints;

o Areas of significant indentation, other than localised mechanical

damage;

Be particularly vigilant after heavy weather;

Rectify any steel-to-steel fault before renewal of rubber packing. Renewal will

not be effective if steel-to-steel contact points are defective, and expensive

rubber packing will be ruined after only a few months of use;

Replace missing or damaged hatch gaskets (rubber packing) immediately. The

minimum length of replaced gasket should be one metre;

Keep hatch coaming tops clean and the double drainage channels free of

obstructions. (Open hatch covers to clean coaming tops and the double

drainage channels after loading bulk cargo through grain or cement ports);

Keep cleats and wedges in serviceable condition and correctly adjusted;

Keep hauling wires and chains adjusted correctly;

Attach locking pins and chains to open doors and hatches;

39

Keep wheels, cleats, hinge pins, haul wires, and chain tension equipment well-

greased;

Test hydraulic oil regularly for contamination and deterioration;

Keep hydraulic systems oil tight;

Ensure the oil tank of the hydraulic system is kept filled to the operating level

and with the correct oil;

Clean up oil spills. If the leak cannot be stopped immediately, construct a

save-all to contain the oil and empty it regularly;

Engage tween deck hatch cover cleats when the panels are closed;

Give notice that maintenance is being performed so that no one tries to

open/close the hatch;

Remember that continuing and regular maintenance of hatches is more

effective and less expensive than sporadic inspection and major repair.

4.1.2 Never

Treat temporary repairs as if these were permanent. The strength of the cover

and ultimately the ship will depend on the quality of repairs carried out;

Ignore serious corrosion, cracking or distortion in the covers and supports.

These are signs of weakness and are potentially hazardous;

Allow grooves to form in the coaming top, especially where the hatch side or

end panel rests when the hatch is closed;

Apply petroleum-based grease or paint to rubber packing;

Remove the rubber ball from a non-return drain valve;

Use anything other than the recommended hydraulic oil;

Leave cleats unfastened when proceeding to sea;

Attempt to open or close any hatch that has a load or cargo on it;

Open hatch covers at sea unless absolutely essential;

Leave open covers unattended when at sea;

Tighten down the cleats so that the hatch cover is unable to move on the

coaming top.

40

4.2 MONITORING AND INSPECTION

Hatch covers and their fittings should be inspected at the end of every cargo voyage

and all findings recorded. Inspections should be planned and held in time for repairs

to be completed before the next cargo voyage. Empty cargo spaces of all cargo and

combustible material if welding torches are used.

4.2.1 Inspect and Check:

Condition, Covers and coamings should be well painted and free from

significant corrosion, cracks and distortion. During an inspection look for:

o Holes and permanent distortion in the plating

o Distortion of beams and/or stiffeners on the underside of the top plate

o Corrosion around welded connections of beams or stiffeners

o cracking of connecting joints and welds

Hatch movement. This should be smooth. If violent movement is observed,

investigate and remove the cause.

Towing and backhaul wires. These should be free of kinks or broken strands.

Repair or replace damaged or worn wires. Use extreme care when handling

wires to avoid injury.

Hydraulic system for leakage.

Hinge pins. Look for wear, particularly at cross-joints and hydraulic cylinders.

Worn hinge pins can cause hatches to slew and misalign at the cross-joint(s).

Misaligned hatch panels will leak.

Drive chain tensioners. Check their condition and adjustment.

Cleats and wedges. Check for physical damage, corrosion and tension when

locked.

Figure 4.1 panel should be in line with next panel

Source: Lloyd’s Register- A Master’s Guide to Hatch Cover Maintenance

41

4.2.2 Drive Chains; Check their Length

Drive chains and associated equipment are fitted in pairs, opposite one another. The

side towing chains, sprockets and hydraulic cylinders on opposite sides should match.

Adjust the tension of chains between panels so that the chains on both sides are

exactly the same length. Do this by removing or adding chain links. If the entire

length of chain needs to be replaced, then replace the chains on both sides at the same

time. Always consult the hatch cover manufacturer for details of chain length. As a

rule, chain sag, measured from the assumed horizontal at mid-point along the chain,

should be a fist wide.

4.2.3 Steel Landing Pads; Check for Wear

Worn landing pads will damage hatch gaskets and cause hatch leakage. When newly

fitted and closed in the sea position, the top plates of adjacent hatch panels should be

level. Any deviation from level is an indication of landing pad wear or permanent

distortion. If noted, investigate fully and repair immediately.

4.2.4 End Stop Pads; Check for Damage

End stop pads prevent hatch panels from overrunning when hatches are fully open.

Look for physical damage.

4.2.5 Hatch Wheels; Check for Alignment

Hatch wheels should align squarely with the hatch track way. If the wheel axle is

worn the wheel will loll. If it does, repair immediately.

4.2.6 Rubber Seals; Check for Elasticity, Mechanical Damage and Permanent

Deformation

When hatches are opened, rubber seals should regain their original shape. If they do

not, check for ageing. Permanent deformation should not exceed 75 percent of the

design compression.

4.2.7 Locking Devices and Hydraulic Cut-Outs; Check that they Operate

Locking devices are often pins or hooks, these should engage when the hatch is open.

Look for physical damage, rusting and seizure. Hydraulic cut-outs should move

freely.

42

4.2.8 Spares

Rubber packing and adhesive has a limited shelf life, so check the date stamp and

discard if beyond the use-by date. There should be sufficient spare parts (cleats,

wedges and gaskets) to complete planned routine maintenance. Always use

manufacturers’ approved spare parts.

4.3 HEAVY WEATHER PRECAUTIONS

The following precautions should be taken if rough or heavy weather or when high

swells are expected or when it is likely that water will be shipped on deck.

4.3.1 Prior To Rough Weather:

Check that hatch cleats are properly secured and adjusted. In rough weather,

hulls are subjected to high racking forces, so it is essential that hatch covers

are held in place but allowed to flex.

Check that all drain valves are operating correctly and that they are open.

Drain valves are the last defence against water entering the cargo space. The

drainage system will be needed during heavy weather, so it must be fully

operational.

As a precaution, briefly pressurise the hydraulic system to ensure that it is

fully charged and that the piping is filled with oil. This has two benefits, first,

it prevents the possibility of seawater entering loose couplings or seals, and

secondly, it eliminates any creep which may have occurred.

4.3.2 After Rough Weather:

Inspect all cleats, drain valves, guides and hydraulic components for damage.

If hydraulic components have been damaged, do not attempt to open the

covers. The emergency opening procedure should be followed until the

hydraulic components have been checked and tested.

Check hatch covers for buckling or distortion.

When opening the hatch covers check for uneven movement and any unusual

noises that may indicate damage.

Check all grease points and re-grease.

43

Figure 4.2 Vessel in rough weather

Source: Lloyd’s Register- A Master’s Guide to Hatch Cover Maintenance

4.4 SAFETY WHEN WORKING WITH HATCH COVERS

The avoidance and prevention of injuries is of paramount importance. Before working

on a hatch, a risk assessment should be completed to identify all hazards. Control and

safety procedures should be examined and modified so that hazards are reduced to

minimal levels.

The following points should be borne in mind:

If entering the hold alone, always ensure someone else knows you are there

and leave a prominent notice at the hold entrance.

Check the lock-back mechanism on the hold access door or manhole is

operational figure 4.3.

44

Figure 4.3 Check the lock-back mechanism

Source: A.Bilbrough & Co. Ltd., Holds and Hatch Covers

Do not use damaged or unsecured ladders, accept in emergencies and then

only with a secured safety harness (figure 4.4).

Check lighting is adequate particularly at the bottom of the ladder. If the hold

is unlit, use a powerful torch attached to a sling or strap across the shoulder.

Figure 4.4 Do not use damaged or unsecured ladders


45

Figure 4.5 Never smoke in a hold.


Figure 4.6 Never climbs on top of bulk cargo without a lifeline


Always have both hands free for climbing up or down ladders; lower or haul

tools and equipment by rope.

46

Figure 4.7 Never carry tools or equipments while descending or ascending a ladder.


Figure 4.8 Never stand on the coaming top when the hatch covers are open.


Always wear protective boots or shoes for working on deck.

Do not stand under openings.

47

Figure 4.9 Always wear protective headgear when working.


Always clean up oil spills. If the leak cannot be immediately stopped, build a

save-all around and regularly empty it.

Exercise extreme care when handling wires.

Figure 4.10 inspect wire for wear, kinking or broken strands at regular intervals.


48

Figure 4.11 Always takes precautions when fumigating.


4.5 Procedures to Open and Close Hatch Covers

Prior to opening or closing a hatch, the watch officer should be informed and the

condition of the hauling wires or chains checked; the hydraulic system should be

topped up. Never open or close more than one set of hatch covers at a time.

4.5.1 Opening Procedures

Check that the hatch cover panel stowage area is clear of people, equipment

and dunnage;

Disengage all cleats;

Attach towing or hauling wires; switch the power on and ensure the controls

are in neutral;

Ensure that all personnel are clear of the hatch and its tracking. Position

crewmembers to observe both sides of the hatch;

Raise hatch covers to the roll position by jacks or by raising the lifting system.

(The panels need to clear the hatch guides);

Check that towing chains are free and do not foul tracks or the coaming top;

Start to open the hatch, slowly at first, then at normal operating speed until the

hatch is almost open and then reduce to slow speed until fully open. Care must

49

be taken when opening hatch covers especially when the speed of opening can

be only partially controlled;

When fully open, secure the hatch with the safety hook or pin before the

power is switched off.

If applicable, remove the towing and hauling wires;

Install portable safety rails, if supplied.

4.5.2 Closing Procedures

Check that the coaming top is clear of cargo or debris;

Check and clear drain channels and entrances to the drain valves;

Check that any damaged wheel tracks, compression bars and landing pads

have been repaired;

Ensure that the hold is clear of people and that access hatches or entrance

doors are open. Check towing chains are free;

Attach towing or hauling wires, switch the power on and ensure the controls

are in neutral;

Remove portable handrails;

Release hatch locking pins or hooks;

Avoid injuries by ensuring that all personnel are clear of the hatch. Position

crewmembers to observe both sides of the hatch;

Check that towing chains are free and do not foul tracks or the coaming top;

Start to close the hatches slowly at first with the speed of closure being

gradually increased to the normal operating speed. As the hatch reaches the

closed position the speed should be gradually reduced. Great care must be

taken when closing hatch covers;

Lower hatch covers into guide pockets using jacks or lifting cylinders. Some

hatches are lowered automatically;

Attach cleats before removing the towing wire or switching power off;

Finally, check no one is in the hold before closing hold access hatches or other

hold entry points.

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4.6 Maintenance and Repair

Poor maintenance of hatch covers causes leakage leading to cargo damage and

represents a hazard to the ship and its crew. Although hatch covers are simple and

durable, their sealing gaskets are easily damaged. The quality of sealing is affected by

lack of alignment and poor gasket compression. When hatch covers are opened at the

end of an ocean voyage, look for signs of leakage such as rust staining or drip marks.

Regular adjustment and repair, by ship’s staff, will reduce the overall cost of

maintenance. Painting double drainage channels will help to prevent corrosion.

Always keep a detailed record of maintenance. Take care during extensive

hatch cover repair to avoid cover distortion.

4.6.1 Rubber Gaskets

Keep clean and free from paint. If physically damaged, permanently set-in or aged,

replace with minimum 1 metre lengths. Always follow the manufacturer’s instructions

when renewing gaskets.

4.6.2 Gasket Channels

If gasket channels are badly corroded, causing the hatch packing to hang loose, the

packing should be removed and the channel repaired by welding new metal strips

which should be painted before fitting new rubber. Always follow proper fire

prevention safety procedures. Make sure that cargo spaces are free of cargo and

combustible material. When conducting extensive structural repairs, remove the hatch

covers to shore.

4.6.3 Hatch Cover Structure

Repair or replace any damaged, worn or defective hatch covers or coamings. Consult

with the ship’s classification society before commencing repair. Paint new structure

immediately.

4.6.4 Compression Bars

Effective sealing is only possible with a straight, undamaged and non-corroded

compression bar. Compression bars which are not in this condition should be repaired

or replaced, taking care to align the bars properly.

51

Remember to carry out a chalk test to check alignment, both during and after repair.

4.6.5 Landing Pads

Hatch sealing is arranged by design to give the correct compression of the gasket

when there is metal-to-metal contact on the hatch landing pad, side plate, or inter-

panel block. If landing pads are reduced in height (check with manufacturers’

drawings) because of wear, repair is essential.

4.6.6 Hatch Wheel Track Ways

Track ways can corrode. They are weakened by abrasive wear and tear. When

weakened, track ways can distort and break, affecting hatch movement and alignment.

Deterioration is visible to the naked eye. Repair by replacing the worn or damaged

material with sufficient new material to restore strength. Always keep hatch wheel

track ways clean and painted.

4.6.7 Hatch Coamings

Look for cracks at coaming corners. If any are found, consult the ship’s classification

society before commencing repairs in case the coaming needs to be reinforced.

Examine coaming support brackets for corrosion where they connect with the

ship’s deck. Make sure coamings and their support brackets are painted.

Coamings can be damaged by cargo equipment during loading or discharge.

Look out for damage and repair if found.

4.6.8 Hatch Cleats and Wedges

It is important for compression washers to be adjusted correctly. A locking nut for

adjusting compression is situated at the base of the cleat. The procedure to alter

compression (see illustrations) is as follows:

Close hatch and secure for sea;

Place the cam of the cleat in the hatch socket as if to lock it, but leave it

unlocked (the cam should move freely and fit snugly in its housing);

Adjust the locking nut until the compression washer touches the underside of

the hatch coaming or its steel washer;

Turn the locking nut one full turn to achieve the desired tension;

52

Do not over-tighten;

Protect the thread on completion.

When closing and securing a hatch for sea passage, check the tension in side

cleats. Cleats should never be adjusted in isolation, adjust all cleats along the hatch

skirt at the same time.

4.6.9 Hatch Cross-Joints

It is essential for the cross-joint to be in good condition and properly aligned.

Maintenance and repair should focus on:

Examination of the cross-joint structure for corrosion.

Examination of joint hinges for pin wear, blade cracking or weld failure.

(Re-grease the hinge pin bushes making sure grease reaches the hinge pins).

Examination of the steel-to-steel inter-panel blocks and locators for wear.

(Check the top plate of hatch panels, they should be level when closed).

Checking the gap between panels when they are closed. Misalignment could

be caused by an incorrectly adjusted cylinder or the wheel tracks could be

worn.

4.6.10 Hatch Wheels

Hatch wheel spindles and bearings (where fitted) need to be greased regularly. Check

the wheel spindle for wear and the wheel housing for physical damage. Repair if the

spindle is worn or if the wheels are out of alignment.

4.6.11 Drain Channels and Non-Return Valves

Clean coaming tops and cross-joint channels by removing any loose scale or cargo

residue by brushing or hosing. Clean coaming drain holes and check that the non-

return valve is functioning.

4.6.12 Greasing

Wheel spindles, cleat spindles, hinge pins, hydraulic cylinder protective sheaths, cleat

wedges, drive chain sprockets, toothed rack and cylinder spherical bearings need to be

kept well-greased. Re-grease every month if necessary, and always apply new grease

after the ship has passed through heavy weather.

53

4.6.13 Painting

Corrosion occurs mainly at the panel ends along the cross-joint or where access is

difficult, but it can also occur on the underside of a panel, especially along hatch

beams. Regular painting will be necessary.

4.6.14 Inert Gas

Hatch covers with a double skin, in the form of a closed box, are filled with inert gas.

After structural repair, the inner spaces must be re-inerted. This is done by inserting

special tablets (available from the hatch cover manufacturer) into the space and

welding shut. Never allow water to penetrate the box construction.

4.6.15 Hydraulic Systems and Components

The cleanliness and viscosity of hydraulic oil must be checked. Samples of the oil

should be sent to a chemist for testing (use the same company that checks and tests

your fuel and lubricating oil). The hydraulic system is provided with bleed points

from which samples can be taken.

Hydraulic oil should be changed every five years or after there have been

significant repairs, such as piping or cylinder replacement.

Hydraulic oil filters should be changed every twelve months. Do not

contemplate repairing the hydraulic system without the proper components and skilled

fitters.

4.6.16 Use of Sealing Tape and Foam Fillers

The use of sealing tape and foam fillers should be limited to:

Emergency use. When hatches are known or thought to be leaking and there is

insufficient time to complete permanent repairs;

Charterers’ requirement. Charterers may require owners to apply sealing tape

when highly water-sensitive cargoes are carried;

Fumigation tape is usually applied to hatch covers during fumigation. The tape

is not heavy duty and should be removed when fumigation has finished.

Foam fillers can be used to fill the air space which is formed along the cross-

joint of two closed panels. In heavy weather foam fillers may be washed away, their

use should never be solely relied upon to prevent water ingress.

54

CHAPTER 5-SINGLE PULL MACGREGOR TYPE

HATCH COVER DESIGN

The hatch cover must be safe to operate, and it must be cost effective, both as an

initial investment and in service, i.e. the maintenance cost has to be low and the

service lifelong. Furthermore, the design of the hatch cover must suit the various

general arrangements of vessels.

Figure 5.1: Single Pull MacGregor Type Hatch Cover

Source: Internet

Single pull cover

1. Rising track.

2. Panel side chains.

3. Falling track (behind coaming).

4. Balancing roller.

5. Eccentric wheel.

6. Screw cleat.

7. Wheel guide rail.

8. Compression bar.

9. Coaming bar, Coaming stiffener.

10. Coaming hatch stay.

55

11. Coaming.

12. Sheave.

13. Cross joint cleat.

14. Panel top plate.

15. Backhaul wire.

16. Wire to winch or crane hook; bull wire.

17. Rubber gasket.

18. Stowage bay.

The model of MacGregor single pull hatch cover is obtained from the ship

named M V IRAN owned by Islamic Republic of Iran Shipping. This was a bulk

carrier which was used to carry sacks of cement in bulk .There were 4 cargo holds in

this ship using MacGregor single pull hatch cover. Team selected the first cargo hold

and its dimensions and reduced to a convenient ratio of 1:25 to make the project.

DESIGN BASIS

NAME : M V IRAN

OWNER : ISLAMIC REPUBLIC OF IRAN

SHIPPING

GENERAL CHARACTERISTICS

CLASS AND TYPE : BULK CARRIER

TONNAGE : 44,468 DWT

LENGTH : 199.50 METER

BEAM : 30 METER

DRAUGHT : 11 METER

DEPTH : 16.0 METER

INSTALLED POWER : 8238 KW

PROPULSION : ONE FIXED PROPELLER

SPEED : 15.25 KNOTS

CAPACITY : 54237M³

NO OF HOLDS 4

HOLD DIMENSION IN METERS

HOLD NO 1 : 37.5 × 30 × 16

HOLD NO 2 : 32.5 × 30 × 16

HOLD NO 3 : 32.5 × 30 × 16

56

HOLD NO 4 : 37.5 × 30 × 16

HATCH OPENINGS IN METER : 18.65 × 11

NO OF PANTOONS : 4

TYPE : SINGLE PULL MACGREGOR TYPE

NOTE : SACK CARRIER

5.1 PARTS DESIGN

After studying all the hatch covers and their safety and operational aspects, team

which comprise of six persons decided to design a working model of a single pull

MacGregor type hatch cover. The various design aspects are given in this chapter.

5.1.1 Hold Design

The hold design was selected from the cargo hold no 1 of the M V IRAN ship. The

model was made in a convenient ratio 1: 25.

Figure 5.2: Hold Design

Source: Team

Length of the hold: 150cm

Width of the hold: 120cm

Depth of the hold: 63.3cm

Plate thickness: 1.5cm

5.1.2 Hatch Opening Dimensions

The hatch opening dimension was exactly followed from cargo hold no 1.

Length: 74.6cm

57

Breadth: 44.5cm

Figure 5.3: Hatch Opening Dimensions

Source: Team

5.1.3 Hatch Coaming Design

The hatch coaming design is made from the ship after looking the minimum

requirements stated in the load line convention.

Figure 5.4: Hatch Coaming Design

Source: Team

Height: 10.3cm

Height of hatch coaming stay: 8.3

Width of hatch coaming stay: 2cm

Thickness of hatch coaming stay: 1cm

Supported area: 14.3cm

58

Number of coaming hatch stay in end coaming: 3

Number of coaming hatch stay inside coaming: 4

Support for coaming (inside): 7.6×7.6 cm square

Number of supports in end coaming (inside): 3

Number of support in side coaming (inside): 4

Thickness of the support: 2cm

Length between supports: 20cm

Thickness of rubber gasket: 1cm

5.1.4 Hatch Cover Design

The model consists of four Pantoons whose design was taken from the ship Pantoons

design.

Figure 5.5: Hatch Cover Design

Source: Team

Length: 58cm

Width: 23cm

Thickness at middle: 3cm

Thickness at edge: 2cm

59

Slope: 1cm

Total number of panels: 4

Numbers of sliding wheels: 4 in each panel

Diameter of sliding wheels: 2cm

Wheel to wheel length: 19cm

Numbers of balancing rollers: 2 in each panel

Diameter of balancing rollers: 3cm

Length between balancing roller: 20.3cm

Type of connection in between two panel: Chain

Chain length between two panel: 20.3cm

Chain size: 0.7cm

Size of chain connector: 4.5cm

5.1.5 Track 1 Design

The tracks design was taken from the Design features of the MV IRAN ship.

Figure 5.6: Track Design

Source: Team

Length: 85cm

Width: 2.54cm

60

5.1.6 Rising Track Design (Track 2)

The rising track design was taken from the ships track design of MV IRAN.

Figure 5.7: Rising Track Design

Source: Team

Overall length: 66.5cm

Slanting height: 14 cm

Straight length: 46.5 cm

Peak height from the deck: 16cm

5.1.7 Jack Design

Since the eccentric wheel is not available for the model size, alternate arrangement for

lifting the track was made using hydraulic jack. Since the team were not designing the

hydraulic jack, the same of appropriate size and adequate power was brought from the

market as per the instructions from project guide and team decision

Figure 5.8: Jack Design

Source: Team

61

Height of jack while normal condition: 15cm

Height of jack while lifted condition: 18cm

Lift of jack: 3cm

Capacity of jack: 2000kg

5.1.8 Crane Space Design

The design of the crane space was taken directly from the ship.

Figure 5.9: Crane Space Design

Source: Team

Height: 35.5cm

Length: 50cm

Breadth: 12.3 cm

Pulley height from weather deck: 32.5cm

Angle of pulley fitted related to base: 40 degree

5.1.9 Motor Casing

The motor casing was designed according to the motor dimensions.

Length: 24.5cm

Height: 25cm

62

Breadth: 10.7cm

5.1.10 Motor Specifications

The motor was selected according to the power required to roll the pantoons over the

track and to pull the pantoons back to position. The motor selection was made after

several trials.

Voltage: 240 V

Current: 12mA

Phase: single phase

Frequency: 50 Hz

Power: 0.003 HP

Torque: 3.5cm

Capacitor: .82 K

Shaft diameter: 1cm

Forward reverse switch: 240 V; 5 Ampere

Push button: 240 V; 5 Ampere

5.1.11 Pulley Design

The pulley was selected according to the dimension of wire rope and the power

required for opening and closing the hatch cover.

Pulley fitted to the motor:

Diameter: 8cm

Numbers: 2

Width: 3cm

63

Pulley for rope

Diameter: 2cm

Width: 1cm

Numbers: 2

5.1.12 Rope

The rope was selected according to the safe working load of the model.

Length: 300cm

Diameter: 3mm

5.1.13 Reduction Gear Design

The selected motor was 60 rpm speed and for the correct working of the hatch cover,

the team designed the reduction gear to reduce the speed into 13 rpm.

Number of teeth in bigger gear: 66

Number of teeth in smaller gear: 13

Actual speed: 60 rpm

Reduced speed:

×60=11.81(12rpm)

5.1.14 Ladder Design

The ladder design was taken from the MV IRAN Ship.

Height: 36cm

Width: 4.7cm

Numbers of steps: 11

Gap between steps: 3.5cm

64

Figure 5.10: Ladder Design

Source: Team

5.1.15 Bulwark Design

The design of the hand rail was taken according to the convenience.

Figure 5.11: Bulwark

Source: Team

65

Height from the deck: 7.2cm

Height to the first cross bar: 3.2cm

Gap between bars: 4cm

Cross bar diameter: 0.4cm

5.2 MATERIAL SELECTION

The material was selected according to the availability in the market and for the easy

fabrication process. The material was also chosen by considering economic limits.

After all discussions with the team members and project guide, for the successful

fabrication of the model the team decided to choose the following materials:

Cargo hold : Ply Wood

Hatch Coaming : Wood

Hatch Stay : Wood

Pantoons : Wood

Sliding Wheels : Plastic

Balancing Wheels : Mild Steel

Chain : Metallic

Chain Connector : Galvanised Sheet

Track : Aluminium

Rising Track : Mild steel

Rope : Iron

Track Support : Cast Iron

Motor Casing : Ply Wood

Pulley : 2 Plastics, 2 Copper

Supports : Steels & Aluminium

66

Hand rail : Galvanised Iron

Ladder : Galvanised iron

Hold supports : Ply woods

Side dog : Wooden

Gaskets : Rubber

Gear : Harden steel

Motor shaft : Polished steel

67

CHAPTER 6 - FABRICATION

The design was made with the specific dimensions and was submitted to project guide

for approval. After making necessary changes as directed by the project guide, the

design was approved. After the approval, team started the fabrication work which is

explained in this chapter.

6.1 FABRICATION OF CARGO HOLD

Ply wood material dimensions brought into workshop:

8 ft×6 ft: One piece

6 ft×4 ft: Two pieces

4 ft× 4 ft: One piece

Figure 6.1: Cargo Hold

Source: Team

Placed on the work table and marked the dimensions as follows:

120 cm×63.3 cm (bulkhead separation forward)

120 cm×63.3 cm (bulkhead separation aft)

150 cm×63.3 cm (side plate starboard)

150 cm×63.3 cm (side plate port)

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150 cm×120 cm (weather deck plate)

150 cm×120 cm (bottom plate)

Marked dimensions were cut accordingly.

These parts were joined together in the shape of cuboid with the help of nail and gum.

Sander machine was used to get the surface finish.

The final hold dimensions:

150 cm×120 cm×63.3 cm

6.2 FABRICATION OF HATCH WAY

Hold space was marked and removed using wood cutter from the cuboid made above.

The dimensions were:

74.6 cm along the longitudinal axis of the hold.

44.5 cm vertical to the longitudinal axis.

Edges were well polished with sander machine.

Figure 6.2: Hatch Way

Source: Team

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6.3 HATCH COAMING FABRICATION

Brought the wooden piece to the work table which having the dimensions:

Length: 300cm

Breadth: 12cm

Thickness: 2.8cm

Length of 300 cm was divided into four parts as follows:

80cm: Two piece

50cm: Two piece

All the four pieces were planed and polished. New dimensions of pieces were:

Length: 80cm Length: 50cm

Breadth: 11.8 cm Breadth: 11.8cm

Thickness: 2.6 cm Thickness: 2.6cm

All the four pieces were joined together with the help of nails and hatch coaming was

made.

Figure 6.3: Hatch Coaming

Source: Team

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6.4 HATCH STAY FABRICATION

Brought wooden reaper of dimension:

Length: 400cm

Breadth: 2cm

Thickness: 1cm

14 pieces were made having length 7.6 cm each and

28 pieces were made having length 3cm each.

These pieces were made into the shape (14 pieces) as shown below:

Figure 6.4: Hatch Stay

Source: Team

6.5 FABRICATION OF SIDE & END DOG

Dimensions of wooden piece which was used:

Length: 320cm

Width: 10cm

Thickness: 2cm

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Using wood cutter length of 320 cm were cut into four pieces

Length: 88 cm (two pieces) Length: 66cm (two pieces)

Breadth: 10cm Breadth: 6cm

Thickness: 2cm Thickness: 2cm

Length of 80cm and breadth of 2.7cm was removed from the 88cm pieces as shown in

the figure 6.5.

Figure 6.5: Side and End Dog

Source: Team

All the parts were plain with planner machine and dog was fabricated.

6.6 FABRICATION OF HATCH COVER

Dimension of the cylinder wooden piece which was taken to the mill:

Length: 70cm

Diameter: 38cm

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Figure 6.6 Pantoons

Source: Team

From the above, four pieces of similar dimensions were made which having the

dimensions:

Length: 7cm

Width: 25cm

Thickness: 3cm

The pieces obtained were taken to the work table. After the plaining and chisel work

the final dimensions of hatch cover were:

Length: 58cm

Width: 22cm

Thickness at middle 3cm

Thickness at the edge: 2cm

For keeping all four hatch covers in line with each other, locking arrangement were

made throughout the length by using wooden reaper.

Hatch cover 1: Locking arrangement at the aft end.

Hatch covers 2 & 3: Locking arrangement at both ends.

Hatch cover 4: Locking arrangement at the forward end.

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Plastic wheels (16 pieces), metallic wheel (8 pieces) and the fitting arrangement were

brought to the working table.

Plastic wheels were fitted at each corners of the hatch cover as shown in figure 6.7.

Figure 6.7 : Pantoons and wheels

Source: Team

Metallic wheels were also fitted according to the balancing dimensions.

Figure 6.8: Metallic Wheels on A Pantoon

Source: Team

Washers were provided on both side of the metallic wheels for the smooth operation.

6.7 SLIDING TRACK FABRICATION

Z-section was welded to the jack top as shown in the figure 6.9.

The dimensions of Z-section were:

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7.5cm toward the hold

10.5cm towards the deck

4cm towards the hold again

Width of the plate was 2.56cm and thickness 0.3cm.

The other end of Z section was welded to the iron plate as shown in the figure 6.10.

A wooden piece was screwed to the iron plate and having dimensions:

Length: 80cm

Width: 2.5cm

Thickness: 2cm

Figure 6.9 Sliding Track

Source: Team

Figure 6.10: Hydraulic Jack and Sliding Track

Source: Team

75

At the top of the iron plate, rail was fitted for the sliding wheels.

6.8 FABRICATION OF RISING TRACK

Material used: Mild steel

Two pieces i.e. rectangular & triangular were made separately and then joined

together to get the final shape as shown in the figure 6.11

Prepared for both i.e. port and starboard side

Dimensions of triangular piece:

Base: 12cm

Perpendicular: 6.5cm

Hypotenuse: 13.65

Thickness: 1.cm

Figure 6.11: Rising Track

Source: Team

Dimension of rectangular piece

Length: 47cm

Height: 6.5cm

Width: 1.5cm

Two supports were provided for the rising track.

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The dimensions were:

Height: 15.7cm

Width: 3.2cm

Thickness: 1.5cm

Four L angles were fitted with the supports as shown in the figure 6.11.

6.9 FABRICATION OF CRANE SPACE

Dimensions were marked on the wooden piece as

Length: 50 cm

Height: 35.5

Thickness: 1.5cm

Two pieces of above dimensions were made

Again marking was done as

Height: 35.5

Breadth: 12.3cm

Thickness: 1.5cm

Two pieces of above dimensions were made

These all four pieces were joined together by using nails and gum to form a

rectangular box.

Top platform dimensions:

Length: 53cm

Breadth: 14cm

Thickness: 1.5

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Figure 6.12: Crane space

Source: Team

Top platform made was fixed at the top of the rectangular box made above as

shown in the figure. A pulley was then fitted at the middle at a height of 32.5cm from

the weather deck

6.10 MOTOR REDUCTION GEAR PULLEY FABRICATION

Motor shaft and the smaller gear shaft were coupled together and bearing is provided.

Bigger gear is engaged to the smaller gear and bearing is provided at each end. Pulley

was fitted to the bigger gear shaft. Motor and gears were covered with casing for

safely purpose.

6.11 FABRICATION OF BULWARK

10m of iron rods of diameter 4mm were brought to the work table.

Four pieces of 150 cm length each were cut by using hack saw.

Two rods were taken and kept parallel to each other at a distance of 3.2cm.

Nails were taken and welded as shown in the figure 6.13.

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Figure 6.13: Bulwark

Source: Team

Distance between the nail: 7cm

Repeat the same process for the remaining two rods.

Rails were provided around the top platform too as shown in the figure 6.13.

6.12 FABRICATION OF LADDER

Two iron rods of length 36cm and diameter 5mm each were brought to the work table.

These rods were kept parallel 4.7cm apart. 11 steps were welded 3.6cm apart.

Figure 6.14: Ladder

Source: Team

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CHAPTER 7-ASSEMBLY OF FABRICATED PARTS

After the fabrication work the team collected the fabricated parts together and

assembled them as per the design stated in the chapter 5.

Different parts which was fabricated separately:

Cargo hold

Hatch coaming

Hatch stay

Side & end dogs

Hatch cover

Sliding track

Rising track

Crane space

Motor assembly

Hand rail

Ladder

Figure 7.1 Assembly of fabricated parts

Source: Team

7.1 ASSEMBLY BETWEEN CARGO HOLD AND HATCH COAMING

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These parts were fabricated separately and assembled together by using nails and for

extra support iron L-angles are provided.

Figure 7.2 Cargo hold and Hatch coaming

Source: Team

Hatch comaing at port and starboard were provided with four L- angles and at

aft forward were provided with three L-angles each. These L-angles were screwed

well into the hatch coming and cargo hold. finally it was assured that the assembled

part is rigid.

7.2 ASSEMBLY OF HATCH STAY ON COAMING

After fitting the coaming hatch stays were provided for additional rigidity of coaming.

14 hatch stays were fabricated separately and were assembled as:

4 at port & starboard each

3 at aft & forward each

Hatch stays were fitted using nails and gum.

Figure 7.3 Hatch stay on coaming

81

Source: Team

7.3 ASSEMBLY OF SIDE DOGS AND END DOGS ON COAMING

For the beading arrangement as well as fitting of sliding track side and end dogs were

provided. These were fitted perpendicular to the coaming.

Figure 7.4 Side dogs and end dogs on coaming

source: Team

Again this assembly was done by using nails.

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7.4 ASSEMBLY OF SLIDING TRACKS

Sliding tracks were fabricated separately and was welded with hydraulic jacks.

Hydraulic jacks well positioned and screwed into the weather deck such a way that

lifting and dropping action of tracks takes place effectively without interruption.

Figure 7.5 Sliding track

Source: Team

7.5 ASSEMBLY OF RISING TRACK

Rising tracks were fabricated and they were fitted according to the position of

balancing wheels. Supports provided for the rising tracks were fitted to the weather

deck with the help of screws.

Figure 7.6 Rising track

Source: Team

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7.6 ASSEMBLY OF HATCH COVER

All the four hatch covers were fitted with plastic sliding wheels at the four bottom

corners. Also metallic balancing wheels were provided at port & starboard ends.

All the hatch covers were made in line above the sliding track. Bottom wheels

were checked for alignment with the tracks.

Figure 7.7 Hatch cover

Source: Team

Chain is attached to each hatch cover’s metallic balancing wheels at both port

and starboard ends. These metallic wheels were checked for their correct alignment

with the rising track.

Figure 7.8 Hatch cover

Source: Team

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7.7 ASSEMBLY OF CRANE SPACE INTO CARGO HOLD

Separately fabricated crane space was fitted over the weather deck at the specific

position as shown in the figure by using nut and bolt arrangement.

Figure 7.9 Cargo space into cargo hold

Source: Team

7.8 ASSEMBLY OF MOTOR PULLEY GEAR ARRANGEMENT INTO

CARGO HOLD

Motor was bolted into the weather deck with the help of nut and bolt arrangement.

The roller bearings supports were too bolted to the weather deck.

7.9 Assembly of Bulwark

Holes were drilled into the weather deck using drilling machine and positions were

adjusted according to the nail position welded.

Figure 7.10 Bulwark

Source: Team

85

The whole bulwark is placed over the drilled holes and forces inside to make it

tight and rigid. The whole bulwark is placed over the drilled holes and forces inside to

make it tight and rigid. Same procedure was followed for the crane top platform and

bulwark fitting.

Figure 7.11 Bulwark

Source: Team

7.10 ASSEMBLY OF LADDER

This is provided to connect weather deck and crane top platform. Top of ladder is

attached to the platform and bottom to the weather deck. Both ends were fitted

permanently.

Figure 7.12 Ladder

Source: Team

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7.11 ASSEMBLY OF LOCKING ARRANGEMENT

For this purpose grooves were provided at each corner of the coaming such a way that

the hatches can lock well during normal voyage. This arrangement will helpful for

avoiding unnecessary sliding of hatch covers.

Figure 7.13 Locking arrangement

Source: Team

7.12 ASSEMBLY OF WIRE ROPE

Wire is provided for pulling hatch covers fore and aft direction with its wheel rolling

between guides on the top of the coaming. For this purpose two eye bolts were

provided to the furthest panel as shown in the figure 7.14.

Figure 7.14 Wire rope

Source: Team

87

Through the middle top eye bolt rope goes to the wheel provided on the crane space

and finally to the motor pulley. Through the bottom eye bolt rope goes directly to

motor pulley.

88

CHAPTER 8-TESTS AND TRIALS

Since the ship trades in all type of environmental conditions including heavy weather

condition etc, there is chance of damage of cargo or goods because of water or

moisture entering to the hold. This may even damage the whole ship so in order to

avoid this, covers are made water tight and same is tested before proceedings. The

two most common leak detection tests are the water hose test and the ultrasonic test.

Ultrasonic testing is the preferred method because areas of inadequate hatch

sealing are accurately located. Chalk testing (another hatch test) gives only an

indication of poor compression and potential leaks. Chalk testing is not a leak

detection test. Light testing is also effective but is potentially dangerous because

personnel are in a closed, dark hold looking for light infiltration between panels. If

hatches are found to leak during a test, make the necessary repairs, then test again.

8.1 WATER HOSE LEAK DETECTION TEST

Water hose tests are used to determine weather-tightness of hatch covers. If correctly

performed, hose testing will show hatch joints that leak.

The general procedure for hose testing is to apply a powerful jet of water from

a 20-50 mm diameter hose fitted with a 12 mm diameter nozzle held at a distance of

1-1.5 metres from a hatch joint, moving along the joint at a speed of 1 metre every 2

seconds.

The drawbacks of hose testing are:

The hold needs to be empty;

It cannot be performed in sub-zero conditions;

It requires the deck scupper drains to be open (potentially causing pollution);

The test cannot pinpoint leaks on the cross-joint or side joint accurately;

Two people are needed to supervise the test.

Care should be taken to avoid excessive nozzle back-pressure.

8.2 ULTRASONIC LEAK DETECTION TEST

Ultrasonic leak detection is a viable alternative to the hose test for testing hatch

covers, access doors and access hatches for weather tightness, as it accurately locates

potential points of leakage. This test should only be carried out using class approved

equipment and approved test procedures.

89

The test involves placing (with hatches closed and secure) an electronic signal

generator inside the cargo hold. A sensor is then passed around the outside of all

compression joints. Readings taken by the sensor indicate points of low compression

or potential points of leakage. Ultrasonic testing overcomes the majority of limitations

associated with hose testing and can be carried out when holds are loaded. The

drawbacks of these section tests are:

The equipment requires an experienced and specialist operator to interpret the

readings.

The equipment requires regular calibration;

The equipment is not normally part of the ship’s equipment.

8.3 PUTTY OR MOULDING CLAY TEST

This is a maintenance test mainly used by the maker’s representative to precisely

determine alignment and clearances. Putty or moulding clay is placed at regular

intervals in the packing retaining channels that have no packing in them. The hatch

covers are closed then re-opened leaving an indentation. This allows the exact steet-

to-steel wear down condition to be calculated and any panel distortion or

misalignment to be measured and remedial action taken.

8.4 CHALK TESTING

When performing a chalk test, the top edge of every compression bar is covered with

chalk.

Hatches are then fully closed and reopened. The rubber packing is examined

for a chalk mark, which should run continuously along the packing centre. Gaps in the

chalk mark indicate lack of compression. Chalk testing merely indicates if hatch

panels are aligned and compression achieved. It will not show whether compression is

adequate and therefore it is not a test for weather tightness.

8.5 TOLERANCE TEST FOR HATCH COVERS

This test is conducted on a jig to check the flatness of adjoining panels, as well as the

dimensions and the hinge pin clearances where multiple panels are measured. It also

checks cross joint steel to steel contact wear down.

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It is a test done following extensive steel repairs to hatch cover panels and is

essential if the panels are of double skinned construction. Always contact the makers

for such testing’s, as original construction information is needed.

8.6 RESULT

Since the model is made of ply wood it cannot withstand the pressure and other

governing regulations, the team was not able to perform the above stated test and

trials. The main idea of presenting the model is to show the working and to know the

basics of the MacGregor type hatch cover.

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CHAPTER 9 - CONCLUSION

Right from the starting i.e., designing of MacGregor hatch cover to its successful

completion the team has given its full potential for the same. First of all, the suitable

design was made. After taking all precautions and factors into consideration the

fabrication process was performed. As the material selected for the hatch covers was

plywood for the easy fabrication and due to economic limits, the various leak tests

were not performed. The model was completed based on the design taken by the team.

The opening and closing trial of the hatch cover was done many times and it

performed successfully and satisfactorily.

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REFERENCES

1. A.Bilbrough & Co. Ltd., Holds And Hatch Covers

2. Buxton, I. L., (1978) Cargo Access Equipment for Merchant Ships, London,

ICHCA.

3. Lloyd’s Register, (2002) The Standard 2002, A Master’s Guide To Hatch

Cover Maintenance.