Inspection of Holds prior Loading:
All holds should be inspected prior commencing loading this may be done while the ship is enroute or just after completion of discharging and prior loading at the same port.
A thorough cleaning of the hold is undertaken; the bilges are cleaned and tried out with an amount of water. If required the hold is hosed down and the water pumped to holding tanks.
This ensures that there is no refuse lying within the holds and that the bilges after loading would if necessary be capable of being pumped out.
The bilges if with offensive smell have to be sweetened.
This is again a necessity to prevent any food cargo from being tainted.
All other lines in the hold are to be pressed up and checked for leaks. Air pipes and sounding pipes passing through the hold spaces are to be checked up with a head of water.
The above ensures that ingress of water into the hold is minimized.
The hold bottom has to be inspected for any dents in the plating.
Some DB’s may be dedicated for fuel oil/ ballast as such this would give a fair idea if the plates have set in or if their appears to be a deep indentation/
All spar dunnage at the ship sides are to be fitted and the frames at the sides have to be inspected.
This is done so that if bale cargo is loaded the shipside steel does not come in contact with the cargo.
The used lashing material has to be removed including all temporary eyes, which had been made.
And if this is not done then the same eyes may be inadvertently be used for new lashing – lashing wires are for one use only and the risk of parted lashing arises by using old lashings.
Use of Dunnage
There are basically a few reasons why dunnage is so necessary on general cargo ships while loading general cargo.
Of prime importance is to keep the cargo away from the steel bottom of the hold. The steel bottom condenses the moisture in the air and these droplets of moisture over a period of time can damage cargo. This is known as ship sweat. And only by dunnage can the cargo be
safeguarded against this. Good ventilation certainly helps but some amount of sweat is ever present.
The second reason why dunnage is spread about on the holds is to bring about some amount of frictional resistance between the cargo and the steel bottom. Thus lashing becomes easier. Another factor is the dunnage helps in spreading the cargo weight evenly.
In the event of small ingress of water the dunnage helps in channeling the water into the bilge wells, if this were not prevented then any accidental ingress of water would be absorbed or retained in pools by the cargo.
If the hold bottom is dirty due to stain and hard coating of earlier cargo and hosing down is not possible then a double layer of dunnage would prevent the cargo in coming into contact with the stain.
In general holds are laid with double dunnage while tween decks are layered with single dunnage.
The size of the dunnage may vary but usually they are about 6” X 1” X 6 feet. These are laid about 6” to 10” apart, though the gaps may again vary depending upon the nature of the cargo. The bottom tier of the hold dunnaging may be laid in the fore and aft direction and the top tier in the athwart ship direction. At the aft of the hold a clearing of two feet is laid with the bottom tier in the athwart ship direction. This helps in the water/ condensation from trickling to aft and then subsequently finding the bilge well.
Tween deck dunnaging is of one tier – exceptionally may be two tiers and it really doesn’t make much difference if the dunnage is laid out in the fore and aft direction or in the athwart ship direction.
For heavy cargo where spreading the weight takes precedence over other hazards, the dunnage or timber used is generally 4” X 4” X 6 feet (they may be also of stouter variety).
These heavy timbers are laid out in the fore and aft direction in order that the load is spread on as many frame spaces as possible.
Dunnaging also forms a very important factor when ventilation is of primary concern
especially when loading a consignment of Rice. Extra channels are created within the bagged cargo to allow good ventilation. Together with double dunnaging being provided between
stacks of 4-6 bags. If this is not done then the cargo sweat that may be generated is not removed and condenses on the cargo itself allowing the cargo to rot.
Dunnage is used primarily for the protection of the cargo from sweat related damage and consequently it is used so that the cargo does not get too closely packed thereby obstructing to the flow of air.
Special cargoes use more dunnage where air channels have to be kept so that the airflow is not hampered. Rice is one such cargo.
Advantage of dunnaging is also from the fact that it spreads the weight of the cargo evenly all across the tank top or tween deck top, but this advantage is a side benefit, the main reason is protection from sweat. And to some extent from heat from the boiler spaces in the engine room.
Dunnage is thus primarily for the prevention of sweat damage to cargo.
The structure of the ship is made of steel, this steel being a good conductor of heat cools down faster than wood as such the temperature of the steel may fall below the dew point of the air within the compartment leading to sweat. However if this steel can be prevented from coming into contact with the cargo by a layer of wood, which being a poor conductor of heat does not cool down so drastically, then the effect of the sweat coming into contact with the cargo and thus damaging the same may be limited.
If despite precautions being taken, sweating does occur, the damage caused may be minimized by adequate dunnaging of the boundaries of the compartment.
The permanent dunnage of the ships side is known as SPAR Ceiling or CARGO BATTENS. It consists of timber about 150mm x 50mm fitted over the side frames. It is usually fitted horizontally into cleats on the frames. There is a vertical distance of not more than 230mm between the battens. On some ships the spars are fitted vertically and this gives better protection to the cargo as well as it suffers less damage and is thus more long lasting. Spar ceiling may also be fitted on the bulkheads at the ends of the compartment; this is especially the case where the bulkhead is the engine room bulkhead.
The tank top should be covered with a double layer of dunnage. The bottom layer is usually 100mm x 50mm or 150mm x 50mm spaced about 300mm apart and laid athwart ships to ensure free drainage to the bilges. If the ship has only bilge wells then it is preferable to lay the dunnage in the fore and aft direction.
The upper layer consists of 25mm boards about 150mm in width laid at right angles to the bottom layer, about 150mm - 300mm apart.
Occasionally burlap/Hessian is laid over the dunnage - this improves the appearance of the hold but restricts air circulation through the cargo,
A permanent wooden ceiling more than 65mm thick is often laid on the tank top in the square of the hatch; this is to protect the tank top and does not replace the dunnaging.
A similar arrangement of dunnage will be found in the tween decks, although double dunnaging is not so commonly found here. Care should be taken to have a good layer of dunnage at the ship’s side over the stringer plate, as water tends to accumulate there.
Secondhand timber is frequently used for dunnage. It should always be inspected to ensure that it is free of stains, odour, nails and large splinters. New timber also has its drawbacks; it should be free of resin and should not have a strong smell of new wood.
The top of the cargo is protected by a covering (especially under the stringer plate) by matting, wood dunnage or some sort of waterproof paper, or plastic sheets.
Single Fore and Aft dunnaging the most common dunnaging:
The second Layer
Contamination of Cargo
Cargoes -which taint easily, e.g. tea, flour, sugar, should be kept well away from strong smells. If a pungent (strong smelling) cargo e.g. cloves, cinnamon has been carried previously, deodorizing of the compartment will be necessary.
Dirty Cargoes should never be carried in the same compartment as “clean” cargoes.
A very general classification for “dirty” cargoes could include paints and oils, steelwork, animal products other than foodstuffs. Similarly a general classification of clean cargo could
include food products and manufactured vegetable products e.g. clothing. Naturally there will be exceptions to both of the above groups.
Reasons for a general inspection of holds
All holds should be inspected prior commencing loading this may be done while the ship is enroute or just after completion of discharging and prior loading at the same port.
A thorough cleaning of the hold is undertaken; the bilges are cleaned and tried out with an amount of water. If required the hold is hosed down and the water pumped to holding tanks.
This ensures that there is no refuse lying within the holds and that the bilges after loading would if necessary be capable of being pumped out.
The bilges if with offensive smell have to be sweetened.
This is again a necessity to prevent any food cargo from being tainted.
All other lines in the hold are to be pressed up and checked for leaks. Air pipes and sounding pipes passing through the hold spaces are to be checked up with a head of water.
The above ensures that ingress of water into the hold is minimized.
The hold bottom has to be inspected for any dents in the plating.
Some DB’s may be dedicated for fuel oil/ ballast as such this inspection would give a fair idea if the plates have set in or if their appears to be a deep indentation.
All spar dunnage at the ship sides are to be fitted and the frames at the sides have to be inspected.
This is done so that if bale cargo is loaded the shipside steel does not come in contact with the cargo.
The used lashing material has to be removed including all temporary eyes, which had been made.
And if this is not done then the same eyes may be inadvertently be used for new lashing - lashing wires are for one use only and the risk of parted lashing arises by using old lashings.
Bilge and Suction Wells
Bilges and bilge wells should be thoroughly cleaned prior loading any cargo and especially if the previous cargo was oil cakes or such other cargo.
Bilges should be cleaned, the suctions tried out and then the bilges should be sweetened with pine oil or such. The bilges should be finally dried.
Prior loading of cargo all bilge wells should be cleaned and then filled with water and the water then pumped out.
Timings for pumping out the water should be noted and compared with the pump efficiency.
While filling the bilge well the sounding as measured by the sounding rod should be checked against the actual as observed inside the bilge well.
The sounding pipe should be checked for any blockage.
The striker plate underneath the sounding pipe also should be checked for wear down.
Deep Tanks
Deep tanks are tanks on general cargo ships, which are accessible from the hold. The lines leading to such tanks are to be blanked off since a slight leakage in such lines can damage cargo in the holds. The man holes to these tanks also has to be ensured that they are water tight. If any liquid is loaded then the thermometer conduits should be checked for any leakage as well the heating coils have to be tested prior loading. The pumping out arrangement has to be tried out before hand.
Covering of Bilge Wells
These suction filters are very easily taken care of. Hessian is used to form a pad comprising of a double layer and this is wrapped around the loose filter covers of the drain wells. The pad should not be so thick that it would absorb water and prevent the water from draining into the wells.
For limber boards the same pads are nailed down between the adjacent boards. And they then serve the same purpose, that is prevent any debris from clogging up the suctions.
Care of Ballast Lines
This is very important, since the inadvertent ballasting of the deep tanks would damage cargo loaded in the deep tanks.
There are many instances of the above happening, bulk carriers of yesteryears often had a hold dedicated as a water ballast tank, in 1978 a new ship off the building yard in
Gothenburg had not blanked off the ballast lines since the line had a double segregation. The vessel proceeded to load grain in a US port and on arriving at a UK port for discharging her cargo, it was found that a substantial amount of cargo in the mentioned hold had become damaged due to leakage of water from the ballast lines.
Separation Of Cargo
Separation of cargo for the above cases is required to prevent claims arising due to short landing and later complications with port authorities and customs for cargo left behind on a ship for which duty is payable
There may be numerous ways of separating cargoes bound for different ports or for same port and different consignees. In general though not all are any hard and fast rule the principle is to ensure that cargoes destined for a particular port or consignee is delivered accordingly.
Failure to do this at the time of loading would create chaos at the discharging port, with short landings – residual cargo, since the excess cargo that would remain would not be permitted to be discharged in a subsequent port without creating more paperwork and expenditure. In fact cases have arisen where ships have been arrested for landing cargo not destined for that port – customs take a very strict view of this in many parts of the world.
Thus it is of paramount importance to ensure that cargoes are efficiently separated and marked so that to an un-initiated the cargo discharge may proceed smoothly.
Port markings may be made by different means for different cargoes, the following are some of the few:
Hessian separation strips, in various colours – used to encircle the parcel
Shoring, blocking and securing the later port cargo, since this would have to be done in any case at the discharging port.
Paper sheets
Lashing ropes with coloured strips of cloth wrapped around the joints-turnbuckles/ shackles/
bulldog clips.
Different cargo used as a separation between two similar cargoes.
Water based colours used as port marking or consignee marking – this method though is used more often for consignee marking.
Where bare steel cargo is loaded oil based paint is also sometimes used, since the others may not be suitable due to partial rusting of the plates as well that hessian strips are in-efficient for these cargoes.
Valuable Cargo
Valuable cargo such as Banknotes or mail earlier used to be carried on general cargo ships in special lockers. If such lockers were not available then some dedicated space, which could be effectively secured, was made available. Newer ships do not have such allotted spaces and today most cargoes of such nature is shipped in containers.
Personal effects are also shipped and unless stated as very valuable is loaded in ordinary holds and are quickly over stowed with other cargo. As long as the over stowage is
incomplete the hold is strictly watched and the watchman is done away with once the cargo is over stowed and the entrance to the hold is locked.
All mail and personal effects are tallied on board – by shore staff as well by a ships staff, the results are then verified. In case of any dispute the authorities are informed before a general protest is made.
Ventilation
On general cargo ships one of the largest number of cargo claims is made for goods, which, have been damaged in transit. Barring breakages and handling damage the most common damage is caused by sweat.
SWEAT is formed when the water vapour in the air condenses out into water droplets when the air is cooled below its dew point.
The water droplets may be deposited onto the ship’s structure known as “ship’s sweat” or on to the cargo known as “cargo sweat”.
Ship’s sweat may run down, and may also drip onto the cargo.
Cargo sweat occurs when the cargo is cold and the incoming air is warm. Cargo sweat that is formed may be absorbed by the cargo or if steel may run down after rusting the cargo.
To avoid sweat and its effects it is imperative that wet and dry bulb temperatures of the air entering and the air contained in the cargo compartment are taken at frequent intervals (once a watch).
If the temperature of the outside air is less than the dew point of the air already in the compartment, sweating will occur.
This gives rise to ship sweat and is most usually found on voyages from warm places to colder places. Especially in winter, on voyages from Singapore to Northern China.
Similarly if the temperature of the air in the compartment (or the cargo) is lower than the dew point of the incoming air sweating will again occur.
This gives rise to cargo sweat and usually occurs on voyage from cold to warmer places.
Especially in winter, on voyages from Northern China to Singapore.
If the latter of the foregoing conditions is encountered ventilation from the outside air should be stopped until more favourable conditions obtain.
It should be noted that indiscriminate ventilation often does more harm than no ventilation whatsoever.
It should also be noted that variation in the angles of the ventilators from the wind cause very different rates of airflow within the compartment.
The angle, which the ship’s course makes with the wind, also affects the flow of air.
The angle, which the ship’s course makes with the wind, also affects the flow of air.