Question 1

A vessel develops a list shortly after a heavy lift has been loaded. The list does not correct when the cargo distribution is checked. What dangerous condition should immediately be suspected, and what is the correct first action?

Accepted Answer

A possible angle of loll caused by negative or very low GM, which is dangerous and requires immediate action — typically lowering the centre of gravity by filling a low double-bottom tank rather than assuming calculations are correct An angle of loll occurs when a vessel has negative or zero initial GM (e.g. due to free surface effect, incorrect loading, or flooding) and lies stably at an angle to either side, rather than returning upright. It is easily mistaken for a simple list caused by cargo distribution, but is far more dangerous because the vessel has effectively lost positive stability. The correct response is urgent action to lower the centre of gravity — typically by filling a low, centreline or low-side double-bottom tank — while being cautious that further free surface effect during filling does not worsen the situation. Calculations alone should not be trusted; the situation must be treated as an emergency until GM is restored.

Question 2

The yacht is loading additional stores and fuel before a long passage, raising the displacement significantly. What effect does this have on stability that you, as OOW, should be aware of?

Accepted Answer

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) Adding weight changes the vessel's centre of gravity depending on where it is stowed, and partially-filled tanks create free surface effects that reduce GM. OOWs should understand these basic stability principles even on smaller vessels without a dedicated loading computer.

Question 3

During a survey, watertight door seals in a transverse bulkhead below the waterline are found to be perished and not closing properly. As Master, what is the significance of this for the vessel's damage stability?

Accepted Answer

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 Damage stability calculations assume watertight subdivision functions as designed. A bulkhead door that cannot seal properly defeats that subdivision, allowing flooding to spread beyond the single compartment the design assumed — this must be rectified before further operation.