Your examiner asks: "What is free surface effect, and why does it matter if a compartment floods partially rather than completely?"

A. Free surface effect is the reduction in effective stability (a rise in the effective centre of gravity / reduction in GM) caused by liquid free to move within a partially-filled space as the vessel rolls — a partially flooded compartment, where water can slosh from side to side, generally has a worse effect on stability than the same compartment fully flooded (where the water mass, though heavier, cannot shift as freely), which is why some emergency response guidance favours either completely flooding or completely draining a damaged space rather than leaving it partially flooded.

B. Free surface effect only applies to fuel and water tanks, never to flooded cargo or accommodation spaces.

C. A partially flooded compartment is always more stable than a fully flooded one, with no free surface penalty in either case.

D. Free surface effect describes wave action on the ship's exterior hull and has no relation to internal flooding.

A. Report it immediately to the bridge/Master — do not wait to "confirm" the problem alone — note the apparent quantity/rate of ingress if safely observable, avoid taking any action (e.g. opening further compartments to investigate) that could inadvertently worsen flooding or compromise watertight integrity elsewhere, and stand by for instructions while keeping the area under observation if it is safe to do so.

B. Attempt to fully diagnose and resolve the source of ingress alone before reporting, to avoid raising a false alarm.

C. No report is necessary unless the water level visibly rises during the time you happen to be observing it.

D. Open adjacent compartments immediately to inspect for similar flooding, before reporting the initial finding.

A. Damage stability standards scale with vessel size, type and the consequence of loss — larger vessels and those carrying passengers represent a greater potential loss of life and asset value if lost, and (generally) have more internal volume/length available to provide additional subdivision, so regulations require them to survive a more demanding flooding scenario (e.g. two or more compartments) rather than the less demanding standard that might apply to a smaller vessel.

B. Vessel size has no bearing on the number of compartments a damage stability standard requires the vessel to survive; the same fixed number applies to every ship regardless of size or passenger status.

C. Smaller vessels are required to survive more simultaneously flooded compartments than larger ones, since they have less reserve buoyancy.

D. Passenger-carrying status has no bearing on damage stability standards; only cargo-carrying capacity is relevant.