Question 1

In BSafe Case Study 13, what action taken for an unrelated reason removed a key protection against the fumigant entering the accommodation?

Accepted Answer

Stopping the accommodation's forced ventilation and closing its flaps after a wave flooded the galley, which removed the positive pressure keeping the fumigant out After a wave flooded the galley through the ventilation trunking, the crew stopped the ventilation system and closed the accommodation's flaps — without considering that this would remove the positive pressure that had been keeping the fumigant from entering.

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.