Seamanship Techniques 2 Episode 5 pps

Cleat Canvas tarpaulinHatch boards Ring bolt for lashing Not lower than 10 ″ 24 ″ supports every 10 ″ Tyzack bar Hatch coaming Hatch coaming bracket flanged Deck stringer vee’d and welde

Cleat Canvas tarpaulin

Hatch boards Ring bolt

for lashing Not lower than 10 ″

24 ″

supports every 10 ″

Tyzack bar Hatch coaming

Hatch coaming bracket (flanged) Deck stringer vee’d and welded to coaming

Freeboard deck Transverse beam

Underdeck

girder

Underdeck transverse Deck plate of increased scantling Seam weld

Corner of hatchway (at freeboard deck)

Forward

Underdeck girder

Butt weld

Queen beam

Ring bolts (for securing hatch tents) (or locking wires)

Side coaming

Cleats Ring bolt

Beam bolts

Tyzack bar

Figure 6.1 Conventional hatch.

Figure 6.2 Hatchway construction detail.

The cleating arrangement was such that once the tarpaulins had beentucked, battening bars (steel) would be inserted on top and secured bywooden wedges It was important to secure the wedge correctly into thecleat, or, when hammering home, the grain could split on the edge ofthe cleat.

Finally tarpaulins and hatch boards were secured by locking bars orlocking wires over the complete hatch, to prevent the coverings fromblowing adrift and as an anti-theft device Should the vessel’s freeboardever be lost, locking bars would also restrict the wooden hatch coversfrom floating adrift, an important factor should the vessel be salvagedafter a sinking

Tarpaulins were always laid with their seam edge athwartships andaway from the fore end of the vessel This gave some protection from theforward prevailing weather Tarpaulins were also marked by eyelets toindicate their newness, while hatch identity was established by the number

of knots placed in the securing lashing, a useful practice when severalhatch tarps were made up and stowed together

Securing the Hatch for Sea

Once the cargo work has been completed, the beams positioned, and thehatch boards replaced, the three tarpaulins will be stretched in the orderstated Battening bars will then be forced between the cleats and thetucked overlap of the two tarpaulins, and secured against movement bywood wedges being hammered into the cleats It is important that thewedge is hammered in from the correct direction, namely with the longside against the battening bar The wedges should be hammered in by use

of a wooden mallet, hammering in the direction of the grain of thewood The flat end of the wedge is forced forward so as to be driven in

by any head-on weather, as opposed to being forced out

The heavy iron locking bars are then secured across the top of thehatch, being hooked under the upper lip of the coaming and drawntogether in the middle of the hatch by means of a worming screwarrangement which may be locked by a padlock The number of pairs oflocking bars to a hatch will ultimately depend on the length of thehatchway and the number of hatch board sections as per rigging plan.Each section of board should ideally be secured by at least one pair oflocking bars

Hatch Tents

As is often the case, when the vessel is working cargo, rain may interruptthe normal working operation With the conventional hatch it proved alaborious task to re-cover the hatchway every time a shower stoppedwork, and so a tent, similar to a bell tent, was hoisted, usually from aderrick head The base area of the tent was sufficient to cover the totalhatchway area, and the tent was secured by tails to a wire stay runningaround the hatch coaming This method was a simple but time-savingexercise, which prevented the cargo getting wet The tent was easy to put

in place and could be just as easily cleared

17 Booby hatch access to hold.

With the efficient opening and closing of steel hatch covers today,

tents are not required for the modern vessel

CONVENTIONAL HOLD

Construction

The hatchway entrance is a cut-away from the upper deck stringer

plates The corners of the hatchway are cut on the round to provide

continuity of strength and prevent shearing stresses causing cracks

athwartships and bending forces causing cracks in the fore and aft line

The corner turns of the hatchway are often fitted with reinforcing bars

to prevent loading and racking stresses (Figure 6.2)

Tank Top Ceiling

This is a wooden sheathing over the double bottom tank tops, usually in

way of the hatch, providing the tank tops with some protection from

wear and tear The ceiling also assists ventilation and drainage of cargoes,

and with many cargoes relieves the necessity for laying of double dunnage

This wood covering may come in one of two forms – either wide

flats, laid on bearers which leave space for liquids to drain off to the

bilges, or set close into a composition of cement and Stockholm tar

When bulk cargoes are being regularly carried, the second method is

often employed, as the drainage spaces tend to become choked when the

first method is used

It is not uncommon to see the most modern vessel with no tank top

ceiling at all, but in this case the tank top itself is normally protected by

having increased scantlings

Turn of the bilge construction is shown in Figure 6.3

Spar Ceiling

This may be in the form of horizontal or vertical wooden battens to

keep cargo off the steel work of the ship’s side Contact between the shell

plate and the cargo tends to lead to excessive cargo sweat damage, and

to prevent this occurrence spar ceiling, sometimes referred to as cargo

battens, is secured in cleats throughout a cargo hold and ’tween deck

Limber Boards

These are wooden boards similar to hatch boards that cover the bilge

bays, which are situated at the bottom sides of the lower holds These

bays run the full length of the hold and should be regularly inspected for

their cleanliness The boards are supported by the tank side brackets

between the floors and the frames

Bilge Suctions – Strum Box

The bilge suction (Figures 6.4 and 6.5) is usually found in the aftermost

bay of the hold Vessels normally trim by the stern, so that this aft siting

is best for drainage within the confines of the hatch Scupper pipes tend

Shell plating Side frame Bracket on frame Spar ceiling

Tank side bracket Lightening hole

Bilge area

Non-return valve Strum box Margin plate Double bottom

CARGO HOLD Wooden limber boards

Wood ceiling Drain hole

Figure 6.3 Turn of bilge construction.

Figure 6.4 Bilge suction – strum box.

Limber boards

Margin plate Strum box

Cement

Non-return valve Shell plate

Turn of the bilge

to drain direct from the afterpart of the ’tween deck into the bay containingthe strum box.

A non-return valve must be fitted clear of the strum, and in the moremodern vessels this valve is situated clear of the bilge area The purpose

of the non-return valve is to prevent accidental run back from thepumps, which may cause flooding in the hold The suction end of thepipe is kept clear of obstructions by the strum box arrangement builtabout the pipe opening This strum box is so constructed as to allow thepassage of water but not the passage of solids, which could interfere withsuction The sides of the strum are either slotted or hinged to a frameworkwhich will allow the box itself to be dismantled for cleaning andmaintenance The whole bay containing the strum is covered by limberboards

General Cargo Vessel Deep Tanks

General arrangements vary especially in the securing of the deep tanklids and the number of tanks constructed It is normal to find deep tanks

in pairs or, if situated in a large hatch, then 2 × 2 pairs, to port andstarboard They are extensively used for bulk cargoes such as grain orchemicals but very often fitted with steam heated coils for the cariage ofsuch things as ‘Tallow’ They may also be used to take on extra ballastwhen the vessel is in a light condition

Hat box pumping arrangements are operated from the ship’s engineroom and the lines are fitted with a blanking off fitment when required.Most systems allow for gravity filling and tanks are all fitted with air andsounding pipes (Figure 6.5)

STEEL HATCH COVER

The more modern type of cargo vessel will be equipped with one of themany types of steel hatch cover which are at present on the commercialmarket (Figure 6.6) The many advantages with this style of cover by faroutweigh the disadvantages They are fast in closing or opening, and thelatest versions are so labour-saving that one man could open up all the

plate Grating over hat box to

allow passage of water

Hat box

Suction to engine room

Figure 6.5 Deep tank suction – hat box.

Rubber gasket Check wire Bull wire Hatch top wedge

Lead sheave

End coaming Track

Wheel guide Side dog Eccentric wheel Balancing roller Side chains

Rising track

Figure 6.6 Single pull steel hatch cover.

hatches of a ship in the time it takes to strip a single conventional hatch.

Their structure, being of steel, is extremely strong and generally forms a

flush surface in ’tween deck hatches providing ideal conditions for fork

lift truck work Steel covers may be encountered not just at the weather

deck level but throughout a vessel, inclusive of ’tween decks Hydraulic

operated covers are simple in operation, but should hydraulic fluid leak

at any time, cargo damage may result The direct pull type must be

operated with extreme care, and all safety checks should be observed

prior to opening the chain-operated types

Steel covers are illustrated in Figures 6.6 to 6.12 and Plates 18 to 23

Opening Single Pull Macgregor Steel Hatch Cover

1 Release the side securing lugs, ensuring that they are correctly

stowed in flush position with the track

2 Clear away any hatch top wedges between hatch sections

3 Rig the check wire to the lug of the leading hatch section and

turn up the bight of the wire on to cleats or bitts

4 Rig the bull wire so as to provide a direct pull to the winch from

the leading edge of the hatch cover

5 Complete all work on top of the hatch covers Check that the track

ways are clear of all obstructions, such as pieces of dunnage etc

Figure 6.7 Securing steel covers Cleating (dogging)

arrangement.

6 Turn down the eccentric wheels by use of bar levers, or by usingthe jacks under the hatch cover sections.

7 Check that the locking pins are securely replaced in the eccentricwheels once the wheels have been turned down to the track, insuch a manner that they will not slip out when the wheel rotates

or when the hatch is in the vertical stowed position

8 Ensure that all personnel are aware that the hatch cover is about toopen, and that the stowage bay for the covers is empty and clear toallow correct stowage of the sections

9 Have a man standby to ease the check wire about the bitts, and,just before hauling on the bull-wire, remove the locking pins atthe ends of the leading hatch section

10 Heave away easily on the bull-wire once the locking pins areremoved, taking the weight of the leading hatch section

11 Ease out on the check wire as the bull-wire heaves the hatch open(Figure 6.6)

12 Once all hatch sections are in the stowed vertical position, thebull-wire should not be removed until the securing chains from afixed point are in position to hold back the hatch sections in thestowage bay area

Screw cleat spanner

Cross-joint cleat [manual]

Eccentric wheel locking pin [secures wheel in high or low position]

Eccentric wheel [manually adjusted to suit high or low positions in conjunction with jacking operation]

Balancing roller spindle Jacking block

Rubber

Screw cleat Balancing roller

Cover lifting jack [manual]

Eccentric wheel turning lever [manual]

Junction piece assembly

Figure 6.8

Figure 6.9 Turning down eccentric wheels.

Pull on lever (under or over motion depending

on hatch design) Remove locking pin Insert bar

18 Single pull Macgregor steel hatch covers in the stowed upright position, showing fore and aft ends

of two separate hatches.

19 Steel hatch cover, with the locking pin seen in the

‘out’ position The eccentric wheels are turned

down on to the trackway so as to raise the hatch.

The securing pin through the eccentric wheel is

clearly seen passing through at the level of the

bush Side dogs are hanging vertically down under

the coaming, and lifting lugs, together with

jacking-up plates, are to be observed above the eccentric

wheel.

20 Chain pull steel hatch covers in the stowed upright position.

22 Hydraulic folding Macgregor steel hatch covers

(weather deck), and hatchway showing a full cargo

of scrap metal.

23 Open hatchway showing exposed ’tween deck space Pontoon covers are stacked in the after end Lower hold contains general cargo Spar ceiling is shown exposed on the lower hold sides.

21 Rack and pinion horizontally stowed steel hatch covers.

Hinged sheave

Stowing arm

Wire pendant Hauling eyeplate Hinge Panel 1 Panel 2 Panel 3

Wheel

Closing arm Securing hook

Stowing arm pedestal Closing arm pedestal

7.8m clear opening

N.B All dimensions given are typical and vary according

to individual installations.

Emergency operation can

be arranged for all installations.

19.2m clear opening

Figure 6.10 Direct pull weatherdeck hatch covers (above).

Side rolling covers (right) Rack and pinion

drive, with hydraulic lifting and cleating.

Optional : quick acting cleat

or hydraulic cleating

Self-engaging locking

at transverse cross-joint

Optional: hydraulic cleating

or quick acting cleat Rack and pinion drive

Figure 6.11(a) Steel hatch covers, ’tween deck.

Trailing pair

Leading pair

Disconnected Fixing bolts

Drag link

One pair external cylinder

Cylinder arrangement

Figure 6.11(b) Weather deck hydraulic folding hatch

covers.

Figure 6.12 Roll stowing covers – Rolltite Originally

designed by Ermans and under manufacture

by Macgregor.

13 Clear away the check wire, coiling it down to one side of thehatch Do not attempt to detach the check wire from the lug ofthe leading edge of the hatch

GENERAL CARGO TERMINOLOGY

Additional dunnage is soft light wood, dry and free from stains, odour,

nails and large splinters New timber should be free of resin and withoutthe smell of new wood Materials also used for similar purpose arematting, bamboo or waterproof paper

Grain Space

This is the total internal volume of the compartment, measured from theshell plating either side and from the tank top to underdeck This measure-ment is used for any form of bulk cargo that could completely fill thespace, an allowance being made for space occupied by beams and frames

Figure 6.13 Use of dunnage.

Measurement Cargo

This is cargo measuring 40 cu.ft per ton (1.2 cu.m per tonne) or more

The standard is used for comparatively light cargo on which freight is

paid on space occupied

Stowage Factor

The volume occupied by unit weight, this is usually expressed in cu.ft/

ton or cu.m/tonne, no account being taken of broken stowage

DUTIES OF JUNIOR CARGO OFFICER

1 Usually taking responsibility for either the forward or after holds

2 Before cargo work begins, he should see that the spar ceiling is in

good order and in place, that holds and bilges have been cleaned

out, and that scuppers and bilge suctions have been tested

3 Ensuring sufficient clean dunnage is allocated to each hold

4 Checking that all cargo-handling gear is in correct working order

and correctly rigged

5 Seeing that hold lighting is checked, and seen to be in good order

6 Checking fire-smothering equipment

7 Having ’tween-deck guard rails rigged, if necessary

8 With conventional hatches, ensuring that any unshipped hatch

beams are secured against accidental dislodging

9 Making hatch tents or other equivalent covering readily available

at short notice in the advent of bad weather

10 Regularly checking on the holds to ensure that the cargo is handled

and stowed correctly, and on loading to ensure that adequate dunnage

is being used in a correct manner

11 When discharging, searching the hold to ensure that no cargo is

left behind, which could lead to overcarriage

12 Noting all times of starting and finishing cargo operations in the

deck log book, together with times of any stoppages

13 Keeping a rough cargo plan showing cargo lots and their distribution,

together with port of destination, tonnage and general particulars

14 Noting all damaged parcels of cargo when loading Any damaged

parcels found on discharge should be landed in a safe place, and

agents and chief officer informed

15 Ensuring hatchways are secured at the end of each working day

16 Constantly watching for pilferage throughout all cargo operations

17 Ensuring ban on smoking is observed in the holds and on the deck

areas

18 Tallying special cargoes, such as mail, bullion etc and providing

lock-up stowage

19 Stowing dangerous cargo in accordance with the requirements of

the ‘IMDG code’ and/or IMO regulations

20 Separating cargo of similar nature but for different ports by separation

cloths, paint or other appropriate separation mode

21 Visiting transit shed ashore periodically to inspect stowage andcorrect handling of cargo.

22 Seeing that fire precautions are observed throughout cargo operations

HOLD PREPARATION

1 The compartment should be swept clean, and all traces of theprevious cargo removed The amount of cleaning is dependent onthe nature of the previous cargo: some cargoes, such as coal, willrequire the holds to be washed before the carriage of a generalcargo Washing is always carried out after the compartment hasbeen swept Drying time for washed compartments must be allowedfor, before loading the next cargo; this time will vary with theclimate, but two to three days must be expected

2 Bilge areas should be cleaned and all ‘bilge suctions’ seen to beworking satisfactorily All ‘holes’ in rose boxes should be clear toallow the passage of water and the lines’ non-return valves seen to

be in a working condition Should the bilges be contaminatedfrom odorous cargoes, it may become necessary to ‘sweeten’ them

by a wash of chloride of lime This acts as a disinfectant as well asproviding a coating against corrosion

3 The fire/smoke detection system should be tested and seen tofunction correctly

4 The holds drainage system and ’tween deck scuppers should beclear and free from blockage

5 Spar ceiling (cargo battens) should be examined and seen to be in

a good state of repair

6 Hatch boards (conventional hatch) should fit correctly and be in agood condition Steel hatch covers should be inspected for theirwatertight integrity about any joints If hard rubber seals are fitted,these should be inspected for deterioration

7 Tarpaulins, if employed, should provide ample coverage and be ofgood quality

8 Hold fitments such as built-in lighting and guard rails should bechecked and seen to be in good order

9 Soiled dunnage should be disposed of New dunnage, cleanand dry, should be laid in a manner to suit the next cargo, ifneeded

10 Hold ventilation system should be operated to check fan conditions

Additional for Special Cargoes

1 Grain Limber boards should be plugged and covered with burlap.

This prevents grain blocking bilge suctions, while at the same timeallowing the passage of water

2 Coal Spar ceiling should be removed and covered (most bulk cargoes

require this)

3 Salt Metalwork should be whitewashed.

STOWAGE METHODS

Bagged Cargo (paper bags)

These should be stowed on double dunnage Ideally the first layer should

be stowed athwartships on vessels equipped with side bilge systems

Steelwork should be covered by brown paper or matting to prevent bags

making contact Torn bags should be refused on loading Canvas rope

slings should be made up in the hatchway centre to avoid dragging and

bursting bags Hooks should never be used with paper bag cargoes

When stowing, bag on bag stow is good for ventilation, whereas bag on

half bag is poor for ventilation but good for economical use of space

Barrels

Stowed ‘bung’ uppermost on wood beds, in a fore and aft direction

‘Quoins’ are used to prevent movement of the cargo when the vessel is

in a seaway Barrels should never be stowed more than eight high

Coal (bulk)

Check that bilge suctions are in working order and that limber boards

are tight fitting Remove all spar ceiling, stow in the ’tween deck, and

cover with a tarpaulin or other similar protection Plug ’tween deck

scuppers Remove all dunnage and make arrangements for obtaining

temperatures at all levels if engaged on a long voyage Ensure that the

coal levels are well trimmed and provide the compartment with surface

ventilation whenever weather conditions permit

Copra

As it is liable to spontaneous combustion, it should be kept dry and clear

of steelwork surfaces, which are liable to sweat Copra beetle will get

into any other cargoes which are stowed in the same compartment

Cotton

Bales are liable to spontaneous combustion, so that the hold must be dry

and clean, free of oil stains etc Adequate dunnage should be laid and all

steelwork covered to prevent contact with cargo Wet and damaged bales

should be rejected at the loading port

Hoses and fire appliances should be on hand and readily available

during the periods of loading, fire wires being rigged fore and aft

Edible Oils

Deep tank stow, for which the tank must be thoroughly cleaned, inspected,

and a certificate issued

Heating coils will be required, and these should be tested during the

period of preparation of the space All inlets and outlets from the tank

should be blanked off Shippers’ instructions with regard to carriage

temperatures should be strictly adhered to A cargo log of these temperatures

should be kept Extreme care should be taken on loading to leave enough

‘ullage’ for expansion of the oil during passage Overheating shouldnever be allowed to occur, as damage to the oil will result.

Flour

Susceptible to damage from moisture or by tainting from other cargoes,

it should never be stowed with fruit, new timber or grain Should a fireoccur during passage, ‘dust explosions’ are liable from this cargo

Fruit

Usually carried in refrigerated spaces, especially over long sea passages, itmay also be carried chilled under forced ventilation However, regularchecks should be made on ventilation system and compartmenttemperatures This cargo gives off CO2 and will consequently requirecareful ventilation throughout the voyage

Vehicles

These should be stowed in the fore and aft line, on level deck space Theyshould be well secured against pitching and rolling of the vessel by ropelashings Fuel tanks should be nearly empty Close inspection should bemade at the point of loading, any damage being noted on acceptance

CARGO HANDLING

Use of Snotters

Rope or wire snotters are in common use when general cargo is discharged.Wire snotters are probably the most widely used, but care should betaken that when using them as illustrated in Figure 6.14, the wire is notallowed to slip along the surface of the steel This possibility can beeliminated by spreading the area of pressure by inserting a dunnage piecebetween wire and cargo Snotters should be secured on alternate sides,passing eye through eye to provide stability to the load

Use of the Bale Sling Strop

A bale sling strop is more commonly known as a sling or even just a ropestrop it is an endless piece of rope whose ends have been joined by ashort splice, used extensively for the slinging of cases or bales, hence itsfull title (see Figure 6.15)

Palletisation

This is a most convenient pre-package cargo-handling technique (Figure

Bundle of steel bars Dunnage piece

Figure 6.14 Use of snotters.

6.16) Separate slings of cargo are made up before the vessel berths,

which speeds up turnround time, so saving the shipowner considerable

port costs The cargo is generally stacked on wood pallets, which allows

easy handling by the use of fork lift trucks The upper layer of cargo

packages are often banded or the full load may be covered by protective

polythene This securing acts as a stabilising factor when the load is being

hoisted, as well as an anti-theft device while the pallet is being loaded,

stowed or discharged

The slings are usually made of steel wire rope, having four legs secured

to a lifting ring Each pair of wire slings holds a steel lifting bar, which

is used to lift the ends of the pallet and its cargo

Each load is usually squared off, to reduce broken stowage within the

hold, especially so when the vessels are of a flush deck and square corner

construction The pallets cause a certain amount of broken stowage, but

this has become an acceptable factor compared to costs of lengthy handling

procedures

Cargo Nets

Fibre rope cargo nets (Figure 6.17) are in general use throughout the

marine industry and are extensively used for such cargoes as mail bags,

personal effects etc where the extra strength and wear resistance of a

wire rope net is not required

Wire rope cargo nets are designed for longer life, and are stouter than

fibre nets They carry a bigger load with greater safety, and tend not to

distort under the most difficult conditions

Fibre rope nets are generally of a knotted mesh, but may be woven

The mesh of a wire rope net will contain a specially designed clip at

every cross, to provide reinforcement for the net as well as protecting the

wire from wear

Timber Dogs

Timber dogs are used purely for the lifting of heavy logs The weight of

the log causes the sharpened dogs to exercise an even greater grip when

inserted into the grain end of the timber Extreme caution should be

observed with this method of lifting, to ensure that the point of the dog

is well embedded before starting the lift (see Figure 6.18)

Plate Clamps

If the construction of the plate will permit this method of lifting, then

it should be employed Whether or not the construction of the plate

structure lends itself to the use of shackles and slings, or to plate clamps,

only one plate should be lifted at any one time

When lifting with plate clamps (Figure 6.19), loads must not exceed

the marked capacity of the clamp, and the jaws must be as narrow as

possible for the plate thickness Before lifting the plate, it should be

checked to ensure that it is properly gripped, and under no circumstances

should packing be used between the jaws and the plate When two

Figure 6.15 Use of bale sling strop.

Four-legged wire or chain sling Lifting ring

Cargo

Wood pallet Lifting

bar

Figure 6.16 Use of pallets.

Figure 6.17 Cargo nets.

clamps are to be used, they should be inclined and secured in the line ofthe sling, once the slack has been taken out of the slings.

Slinging Sheet Metal

In this operation plate dogs (Figure 6.20) or can hooks (Figure 6.21) can

be used They are based on a similar holding operation, where the hooks

or dogs are tensioned together by a single chain sling (per pair) drawingthem tight about the load The purpose of the adjustable spreader (Figure6.20) is to prevent the two slings closing up and disturbing the stability

of the load

Use of Chain Slings

Chain slings (Figure 6.22) are used for such heavy types of load as metalcastings Extreme care should be observed with any load, but even more

so with a heavy lift, especially if chain slings are employed There is atendency for links in the sling to kink inside each other, and if the sling

is pulled clear, the links or any kinks in the chain could cause the load

to tip, with possible dangerous consequences It should be rememberedthat a kink in a chain is a severe weakening factor and should be avoided

Forced

More recent developments in ventilating systems have led to air beingpre-dried before entering the hold In some cases the temperature of theair as well as its humidity may be controlled before entering thecompartment (Figure 6.24) This artificial or forced ventilation, has becomeincreasingly popular because, when properly used, it can almost preventany sweat damage to cargo

REFRIGERATED CARGOES

Refrigerated cargoes include meat carcases, carton (packed) meat, fruit,cheese, butter, fish and offal Ships are specifically designed for theircarriage, with separate spaces in holds and ’tween decks, each fitted withsuitable insulation and individual control of ventilation Ordinary generalcargoes may be carried in the spaces at other times, the temperaturebeing regulated accordingly for the type of cargo being carried

Incorrect

Correct

Figure 6.19 Use of plate clamps.

Two chain slings

Lifting ring

Adjustable spreader

Plate dogs

Lifts should be made with

the dogs fully loaded or

with suitable packing.

Figure 6.20 Use of plate dogs.

Insulation around a compartment consists of either a fibreglass or

polystyrene type of packing over the steelwork of the vessel, with an

aluminium alloy facing This insulation is comparatively fragile and requires

regular inspection and maintenance

Cooling a compartment on modern vessels is achieved by circulating

pre-cooled air by means of fans The air is cooled by an ordinary refrigeration

plant employing a refrigerant with the most practical qualities, namely, a

high thermaldynamic efficiency, low costs, low working pressure, low

volume non-toxicity, non-inflammability, non-explosivity and ready

availability from numerous sources

Typical Refrigerants Carbon dioxide (CO 2 ) Non-poisonous, odourless, with no corrosive action

on metal It has a low boiling point but a high saturated pressure

Ammonia (NH 3 ) Poisonous vapour, and therefore requires a separate

compartment of its own It will corrode certain metals, e.g copper Has

a lower saturated pressure than CO2

Freon (CCl 2 F 2 ) Non-poisonous, non-corrosive, and has a low saturated

pressure By far the most popular in modern tonnage

An older style of reefer vessel had banks of brine-carrying pipes fitted

about the cargo compartment, but these are becoming increasingly rare

with the more up-to-date technology

Properties of a Good Insulating Material

1 Odour All material used should be odourless to prevent tainting of

cargoes

2 Vermin The material should be of such a nature, or so treated, that

it will not harbour vermin

3 Moisture The material should not readily absorb moisture.

Figure 6.21 Use of can hooks.

Figure 6.22 Use of chain slings.

Cowl, covered with protective gauze

Hand grips Aperture – to accommodate wooden plug once cowl is removed (cowls are often removed if bad weather is expected) Plugs subsequently covered by canvas.

Coaming – mild steel welded construction

Ventilator shaft to hold

Figure 6.23 Cowl ventilators.

Ventilators open

Ventilators closed

4 Fire Insulation material should be non-combustible, if possible,

but at least fire-resistant

5 Cost The financial outlay must be considered in view of the quantity

of material required

6 Weight Not as important as one might think for merchant vessels;

however, for ports with shallow water this would become a factorfor consideration

7 Maintenance Costs of installing and of maintaining the insulation

in good condition should be considered at the out stage

building/fitting-8 Settling Value of the material is lost if, after settling, the air pockets

left will necessitate repacking

9 Durability Must be considered in comparison to the life of the

vessel

10 Strength A great advantage would be if the material was of such

quality as to withstand impact when loading or discharging

3 All bilges must be cleaned and bilge suctions tested

4 ’Tween deck scuppers must be tested, together with all ‘U’ brinetraps

5 Bilge plugs should be inspected and sealed Cover plug over bilgesuction may be left off for the purpose of survey

6 Fans must be checked for direction of air flow

7 Bare steelwork must be insulated

8 All odours must be cleared from the compartment

9 All outside ventilation must be shut down

10 Pre-cooling of the compartment must take place before the cargo

is received, times being noted in the cargo log or deck log book

11 Before loading, the compartment should be surveyed The surveyors’comments together with the opening temperature of the chambershould be recorded in the mate’s deck log book

Any dunnage required for the cargo should be of a similar standard ofcleanliness as that of the compartment All slings, chains etc should also

be clean and pre-cooled in advance of cargo reception

CARRIAGE OF GOODS IN DEEP TANKS

Deep tanks are cargo compartments that may be used for the carriage ofdry or liquid cargoes They are usually found in dry cargo vessels at thebottom of one of the holds, forming what would normally be the lowerhold portion of the hatch Some vessels were built with deep tanks either

side of the shaft tunnel (three-island type vessels), where they ran from

the midships machinery space, aft

The openings into the tank are as follows:

8 CO2 or steam smothering line (not always fitted)

9 Steam inlet pipes for heating coils

When the tank is to be used for dry cargo, the following actions should be

carried out before loading the cargo:

(a) Open CO2 or steam smothering lines, if fitted

(b) Blank off ballast line.

(c) Check bilge suction and leave the bilge line open.

(d) Blank off steam inlet to heating coils Coils may sometimes be

removed

(e) Open or close ventilator trunks, as required.

When the tanks is to be used for liquid ballast, the following actions are

necessary:

(a) CO2 or steam smothering lines should be blanked off

(b) Bilge line opened.

(c) Steam inlet to heating coils sealed off.

(d) Ventilator trunks opened.

(e) Ballast bend fitted.

( f ) Main lid hard rubber packing should be inspected and checked for

deterioration If found in good condition, the locking bolts should

be seen to be well screwed down to obtain even pressure on the

seal Manholes should be treated in a similar manner

Preparation of Deep Tanks to Receive Liquid Cargo

Tanks must be tested by a head of water equal to the maximum to which

the tank may be subjected, but not less than 2.44 m above the crown of

the tank The rubber seal should be inspected for any signs of deterioration

about the perimeter of the main lid Any rubber gaskets about the

inspection manholes should be seen to be in good order and to make a

good air/water seal

After the tank has been tested, it should be thoroughly cleaned and

sealed No rust spots or oil patches etc should be visible Hat boxes and

wells should be meticulously cleaned and sealed off, and ballast and CO2

lines blanked off Pressure valves should be fitted into ventilators and the

steam coils fitted and tested

Once all preparations have been completed, the tank must be inspected

by a surveyor before loading and a certificate of the tank’s condition will

be issued

T ABLE 6.1 Cargoes carried in deep tanks

Containers of all sizes are generally loaded by a shore side gantrycrane, travelling the length of the quay on trackways These cranes areusually equipped with automatically controlled lifting mechanisms tofacilitate the lifting and loading of units The jib section of the gantrycrane being lowered from the stowed elevated position after the vesselhas berthed alongside

It would appear that in container operations one of the more sensitiveareas for accidents to ships’ personnel is ashore in the container stowagearea Straddle trucks, often referred to as elephant trucks, used for thetransportation of containers from the park to the gantry crane, are driven

by drivers in a highly elevated position The field of view is somewhatrestricted by the structure of the trucks, making the area extremelydangerous for unauthorised personnel

The disadvantage of the container trade is that an empty containerwith no load to refill it becomes a liability, left at the wrong end of thetrade route Consequently, the majority of container designed vessels will

at some part of the voyage carry to and fro some empty units This means

a limited loss of revenue to the shipowner, though a necessity for thecontinuation of the operation

Ship’s officers should be aware that containers should be loaded in aneven manner, both athwartships and fore and aft, to maintain the stability

of the vessel Not all containers are in a fully loaded condition, so thatthe centre of gravity of the containers will vary This will affect the finalcentre of gravity of the vessel on completion The problem is that unlesseach container is opened up on loading, the ship’s personnel have onlythe shore authorities’ word with respect to the weight and CG of thecontainer However, it should be remembered that most container terminalshave means (weigh bridge) of checking container weights

ROLL ON–ROLL OFF SYSTEM

Roll on–roll off (Ro Ro) methods of handling cargo have developed