Cargo Handling and Stowage: Planning, Securing and Documentation
The cargo plan as a control document
A candidate must be able to build a plan that satisfies stability, stress, segregation, ventilation and lashing requirements simultaneously. Know how to use a loading computer, but also how to sanity-check its output against hand calculations.
Dry bulk and grain
Understand the angle of repose, the grain code's requirements for heeling moments and assumed filling of partially filled compartments, and the risk of liquefaction in mineral concentrates. Know the transportable moisture limit and why a cargo above it can shift suddenly.
Dangerous goods and segregation
Know the classes, the meaning of the segregation table, and the difference between segregation and separation. Understand the requirement for a dangerous goods declaration, stowage away from living accommodation, and the special risks of class 1 and class 7 cargoes.
Containers, heavy lifts and securing
Understand stack weight limits, lashing calculations, the effect of a heavy lift on GM and list, and the need to check deck load limits and hatch cover strength. Know the purpose of a cargo securing manual and the meaning of a lashing's safe working load.
Traps
- Treating a loading computer result as proof rather than as a calculation to be verified.
- Forgetting that a high centre of gravity of cargo raises KG even when displacement is unchanged.
- Overlooking ventilation requirements for hygroscopic cargoes.
- Assuming a container's declared weight is accurate.
Worked example
A 40 t lift is loaded 4 m off centreline on a 8,000 t displacement vessel. The heeling moment is 160 t·m. Using the vessel's GM of 1.0 m, the resulting list is approximately the heeling moment divided by displacement times GM, giving 0.02 radians, about 1.1 degrees. Check this against the acceptable list before lifting.