Q. You have to load vehicles and general cargo on main deck. How will you go about it?
Deck cargo is normally loaded on decks of multipurpose general cargo ships. It must be done in compliance with the carriage rules. Sometimes, a special agreement is made in this respect. Conventional method of carriage on certain routes is usually referred as source of information. On the decks of other ship types, normally, deck cargo is not loaded except as permitted in case of certain type of cargoes and for a particular segment of voyage. Normally, ‘Loading and Stability Manual’ should be used as a guide.
Q. What will you do if in doubt?
Normally, the following considerations may influence the loading on deck:
1. Customary carriage on deck.
2. Legal necessity or prohibition to carry on deck (e.g. limitations caused by assigned freeboard, local regulations, etc.)
3. Increased cargo insurance and terms between Charters and owners.
4. Safety of ship and personnel.
5. Safety of cargo in prevailing weather.
In case of doubt I will consult owners who may get the matter clarified further from Class, P&I, etc.
Q. What factors must be considered prior to agreeing to load on deck?
Apart from the factors as stated above, following must be considered:
1. Size of deck cargo vs. space available.
2. Securing points (whether additional eyes, etc must be welded.)
3. Weight of deck cargo vs. permissible load calculated from the load density of deck.
4. Securing of booms/ cranes, which should not be obstructed.
5. Sounding pipes, cleats (securing hatch covers), etc. must be accessible.
6. Method of securing. Thus, if the lashing ropes must be pre-laid and whether the lashing material is adequate.
7. Guidance regarding securing must be taken from ‘Ship’s Securing Manual’ and ‘Lashing Code’. Annex XIII of code provides sample calculations explaining adequacy of strength against rolling, pitching and tipping.
Q. How will you go about preparing a loading plan on a general cargo ship?
On a general cargo ship there may be the following three situations,
1. Complete loading of bulk cargo.
2. Complete load of general cargo with the plan made by a shore planner or a charterer’s representative.
3. A booking list of cargoes provided to ship and Chief Officer making the tentative cargo plan.
Normally, when a full load of bulk cargo is to be loaded, the reference from previous loading and ‘Loading and Stability Manual’ is taken to decide upon the hold-wise distribution. Load density of each deck as well as maximum permissible load of each space is considered. When a ready cargo plan (made by a shore planner) is given to the Master, a careful study of the plan must be done from the following angles:
a. Total weight in a compartment or in a location must not exceed the safe limit as determined by the respective load density.
b. Plan must be studied for each of the intermediate stage, where stability, stress as well as the remaining cargo’s securing arrangements must be considered.
c. A rough rule of thumb, viz. 65% of total weight must be loaded in lower holds.
d. Separation of the cargoes for different ports is best done tier-wise. If a vertical separation is considered, it should always be athwart-ships, making the consignment for later ports in forward and aft under deck areas. This means, one should not have walls of cargo on port and starboard wings (for later ports).
e. Compatibility of cargoes is important.
f. Fragileness, weight, odour, content, etc. should be considered if overstowing has to be done.
g. Port rotation and accessibility to cargoes at intermediate ports is a very useful consideration.
h. Precious cargo, frozen cargo, mandatory deck cargo, heavy steel cargo, cargo of high stowage factor, dirty cargo, cargo with powdery or liquid contents, etc. are the other considerations.
i. The stowage factor of cargo consignment or size of individual unit.
j. Sometimes, the availability of cargo gear from ship or shore as well as the other limitations, influence the making of cargo plan. Thus, if cargo must be discharged using fork lift at discharge port then a landing place must be created for the fork lift to maneuver. When booking list is provided to ship, the Chief Officer allots locations to different cargoes after considering the various factors stated above.
Q. From where can you get the information regarding load density?
The information is available in G. A. plan, ‘Loading and Stability Manual’, Ship’s Particulars and sometimes, in Rigging Plan. The load density of tank top normally is maximum. The load density of tween decks, main deck, pontoons, hatch covers, etc. is much less.
Q. What are the various documents, necessary to plan and execute various cargo related activities?
Various useful documents are Loading and Stability Manual, G. A. Plan, Chain Register, Rigging plan, Ship’s Cargo Securing Manual, Lashing Code, load line zones, charter party and blank cargo plan. Records from previous loadings can also be useful reference. Thomas stowage, IMDG Code, data sheets, information provided by shipper, etc are very important too.
Q. What information is available in rigging plan?
Rigging plan contains the information necessary for rigging of a lifting appliance such as derrick, crane, etc. Thus, method of rigging derricks, whether as single or modified to lift heavier weights or in union purchase, can be obtained from this plan. Rigging plan is particularly useful when a specialised rigging has to be done for the loads heavier than normal. Sometimes, even crew may not be well-versed with the special rigging. Chief Officer must always consult the rigging plan and check the various details such as location/ SWL of shackles; positioning of slewing guys; safe working load of various components; etc. Some ships have the provision of modifying a light derrick used in union purchase by isolating it and using the same in Gun tackle or Luff tackle. Sometimes, a single heavy lift derrick (Jumbo), which is normally not in use has to be rigged. Slewing guys have to be rigged for operating jumbo and single swing derrick used in gun tackle etc. Detailed information like size of ropes used, SWL of guide blocks, shackles and the recommended rigging is provided in the rigging plan. This plan is also useful when spares and wires related to cargo operation have to be indented.
Q. Sometimes, SWL 5/10t is marked on the booms of union purchase. What does it mean?
It means that the derrick in single swinging derrick mode has SWL of 5. If modified as provided in rigging plan, can lift 10t.
Q. What about union purchase?
In union purchase the cargo booms are stationary during operation. Only the cargo unit moves and hence can be operated at a very high speed. Lifts not exceeding 1/3rd the safe working load of single derrick are handled.
Q. What if a cargo unit to be lifted is heavier than the SWL permitted in Union Purchase or in single derrick lifting?
The single derrick, if modified as provided in rigging plan and attached with slewing guys can be used to lift heavier weights.
Q. What if a cargo unit is much heavier than the strength of deck where it has to be loaded?
The dunnage of appropriate size may be used to spread weight over deck extending to the strength members underneath, so that the total weight over a given area does not exceed permitted load. Girders, frames, beams, floors, etc. may be the strength members below the loaded deck.
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