During preparation of cargo holds for loading, how does the design of the cargo hold bilge system normally prevent sea water or ballast water from entering the hold via the bilge line?

A. By keeping the bilge suction valve permanently locked shut and sealed with wire and lead seals

B. The bilge line is fitted with a non-return (one-way) valve, which allows water/bilge to be pumped out of the hold but prevents water from flowing back into the hold from the bilge piping system

C. By fitting a screw-down valve that the chief officer must manually open and close before and after every use

D. By disconnecting the bilge pipework entirely before loading

A. Only the Chief Engineer needs to consider this, never the deck watchkeeper

B. None — stability is fixed regardless of loading

C. Increased displacement generally raises the centre of gravity if weight is added high up, and free surface effects in partially-filled tanks can reduce the effective metacentric height (GM)

D. Additional weight always improves stability regardless of where it is placed

A. This only matters when the vessel is at anchor

B. Negligible — watertight doors below the waterline are rarely closed anyway

C. Only relevant if the vessel carries passengers

D. Significant — a failed watertight closure compromises the subdivision the vessel's damage stability calculations rely on, potentially allowing progressive flooding between compartments in the event of damage