What is the difference between 'variation' and 'deviation' when correcting a magnetic compass course to true, and why does the order of applying them matter?

A. They are the same correction applied twice for accuracy

B. Variation is the difference between true and magnetic north at a given place (from the chart, changes with location), while deviation is the error specific to that vessel's own compass caused by nearby magnetic materials/equipment (from the deviation card, changes with the vessel's heading) — deviation must be applied to the compass course to get magnetic, then variation applied to get true, since deviation is defined relative to the compass reading itself

C. Variation applies only to gyro compasses, deviation only to magnetic compasses

D. The order never matters since both corrections are always the same sign

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