What is 'heeling error' in a magnetic compass, and when is it most likely to matter?

A. An error that only affects gyro compasses, not magnetic compasses

B. A temporary deviation induced when the vessel heels (rolls/lists), caused by the change in the relative position of the compass to the vessel's own magnetic material as it tilts — it is most significant on steel-hulled vessels and can be reduced by a heeling error coil/magnet correctly adjusted, and matters most in a seaway or during a sustained list

C. A permanent, unchanging error that is identical regardless of sea state

D. An error caused only by proximity to the ship's galley equipment

A. The tidal height at the time of transit to confirm sufficient under-keel clearance

B. The yacht's fuel consumption for that leg

C. The colour of the seabed shown on the chart

D. Only the distance to the next waypoint

A. Switch the ECDIS to standby mode and navigate by GPS position alone

B. Ignore it — ECDIS alarms are frequently false and can be left running

C. Assess the situation against the planned route and charted depths, take action to maintain safe water, and inform the Master if there is any doubt

D. Acknowledge and silence the alarm immediately so it does not distract the helmsman