Question 1

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 2

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.

Question 3

Before departure, several additional guests and a large amount of luggage/provisions are loaded, along with launching the tender. How should this affect your pre-departure checks as Master?

Accepted Answer

Reassess the vessel's loading condition (draft, trim, freeboard, stability margins) against the approved loading conditions, particularly if weight is added high up (e.g. on upper decks) or the tender's stowage/launching affects stability or freeboard Even modest additions can shift draft, trim and stability margins on smaller vessels, especially weight added high (sundeck stores, davits/tenders). The Master should sanity-check the loading condition against approved limits before departure, not assume it is negligible.

Cargo & Stability Practice Questions