You are in clear visibility. The vessel ahead alters to starboard and sounds three short blasts. What does this signal mean and what action do you take?

A. Three short blasts on the whistle means "I am operating astern propulsion" (Rule 34(a)). The vessel is going astern on its engines. You should assess the effect on the vessel's movement, determine if risk of collision exists, and take early and positive action if required. Note: this signal indicates the ENGINE is operating astern, not necessarily that the vessel is moving astern through the water.

B. Three short blasts means "I intend to alter course to port." You are the stand-on vessel and should maintain course and speed.

C. Three short blasts is a distress signal under Annex IV. You should prepare to render assistance and contact the MRCC.

D. Three short blasts means the vessel is not under command. Alter course immediately to starboard to pass astern of the vessel.

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