What does taking a 'meridian altitude' of the Sun at local apparent noon give you directly, and why is it a particularly straightforward observation?

A. It gives longitude directly, with no further calculation required

B. At the moment the Sun crosses the observer's meridian (local apparent noon), its altitude gives latitude directly via a simple calculation (90° minus the corrected altitude, adjusted for the Sun's declination) — it is straightforward because at that instant the Sun's bearing is due north or south, removing the need for the full sight-reduction/intercept method used for other observations

C. It gives an instantaneous fix for both latitude and longitude simultaneously with no further working

D. It can only be used at the spring and autumn equinoxes

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