During your oral exam you're asked what actually determines whether a rising parcel of air keeps climbing or sinks back to where it started. What is the deciding factor?

A. Whether the parcel stays warmer — and therefore less dense — than the surrounding air at each height it reaches; if it does, it keeps rising, if it cools faster than its surroundings and becomes denser, it sinks back

B. Whether the surface wind speed exceeds a fixed threshold at the time the parcel begins to rise

C. Whether the parcel started rising over land rather than over open water

D. The time of day the parcel began to rise, independent of temperature

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