When the cargo loading plan is agreed, the master and terminal representative should confirm the method of cargo operations so as to ensure no excessive stresses on the hull, tank top and associated structures, and exchange information to avoid any structural damage to the ship by cargo handling equipment.
The terminal representative should alert the master, when the cargo is heavy, or when the individual grab loads are large, that there may be high, localized impact loads on the ship's structure until the tank top is completely covered by cargo, especially when high free-fall drops are permitted. As such impacts have the potential for causing structural damage, special care should be taken at the start of the loading operation in each cargo hold.
Special care needs to be taken with heavy cargoes such as iron ore, scrap iron, lead and other concentrates.on general bulk carriers with uniform hold lengths alternate hold loading or block hold loading may be utilized to stow high density cargoes. With such loading arrangements high shear forces occur at the ends of the holds requiring additional strengthening of the side shell in way of the bulkheads.
The loader chute, spout or grab should be kept as close to the tank top as possible and loading should be started at a low rate until the tank top in the loading area is covered with a layer of cargo. As the pile builds up on that area the cargo will roll down the pile and slowly spread over the rest of the tank top without any heavy impact.
Monitoring of the cargo handling operation, and effective communication between the terminal and ship, must be maintained at all times, and especially during final trimming of the ship.
Communications may be maintained by all or any of the following:
a) Direct verbal contact between the designated ship's officer and the terminal representative.
b) Portable radio communication between designated officer, terminal representative and/ or loader operator.
c) Telephone and/or easily accessible Talk Back speakers on loader structure to allow surveyor/designated ship's officer/terminal representative speak directly with loader operator during trimming operations.
Any requirement for cargo trimming should be in accordance with the procedures of the IMO Code of Safe Practice for Solid Bulk Cargoes (BC Code).
The master, the terminal representative and the loader operators at the load port should bear the unloading of the cargo in mind while they are loading the ship. They should, where possible, avoid trimming cargo on to beams or ledges from where it will be difficult or unsafe to remove.
In order to effectively monitor the progress of the cargo loading operation it is essential for both the master and terminal representative to have readily accessible information on the total quantity loaded, as well as the quantities per pour.
a) The loading belts should be run empty before the 90% survey if there is any doubt about the quantity of cargo remaining on them.
b) Where applicable scale weights should be checked against the draught survey estimates of cargo loaded and cargo remaining to be loaded, and allowances made for the balance to be loaded.
c)The quantity of cargo to be trimmed into the fore and aft holds should be delivered exactly as required to ensure the ship finishes with the required fore and aft draughts and trim. This will ensure it will be able to depart from the load port and proceed to and arrive at its unloading port safely and with the required under keel clearance.
On completion of loading, the master and the terminal representative should agree in writing that the ship has been loaded in accordance with the loading plan, including any agreed variations.
The ship's agent should assist in preparing the necessary documentation on completion of loading.
Ships responsibility during cargo operation:
The ship is responsible for loading the cargo at all times. The safety of the ship and those onboard is paramount. In preparing for any cargo loading operation, commercial understanding and cooperation with the loading terminal is essential to ensure maximum efficiency. The loading of the ship must be done in accordance with the ship's instructions, not those of the terminal. In the event of any unresolved differences involving safe loading or the safety of the ship after loading, in addition to advising owners agent or operating office it is recommended that the situation is discussed with the port safety services or the coastguard.
Measures against shifting of bulk cargo
Generally, to prevent cargo shift, bulk cargoes with an angle of repose less than 35° should be trimmed level to fill spaces within the cargo hold. This is not such a problem in bulk carriers with wing tanks designed to fill the top spaces within the hold.
Another advantage of trimming cargoes is that it reduces their surface area, reducing the possibility of spontaneous combustion by cargoes such as concentrates.
Most modern ports now use flexible extending grain chutes capable of rotation to reach all parts of a hold. At the final stages of loading, bulldozers can be used to trim the cargo.
In most cases, the angle of repose is provided by the shipper before loading. If there is any doubt, the IMSBC code provides detailed procedures for its calculation.
What is angle of repose ?
The maximum slope angle of non-cohesive (ie, free- flowing) granular material. It is measured as the angle between a horizontal plane and the cone slope of the material.
Deck officer of the watch/ cargo officer duties
During the cargo watch, as well as the normal duties expected of an officer of the watch (OOW), the cargo officer should: