Radar and ECDIS both suddenly show erratic or clearly wrong readings during a coastal transit. What is the correct troubleshooting priority?

A. Trust whichever system was more recently calibrated and ignore the other entirely

B. Immediately cross-check both systems against independent sources — visual bearings, depth soundings, GPS/GNSS position if separately verifiable, and manual plotting — while treating both electronic systems as suspect until the fault is identified, since simultaneous erratic readings on two systems often indicates a shared root cause (GPS/GNSS interference or spoofing, power supply issue, or a common sensor feed) rather than two independent coincidental failures

C. Continue on the current course and speed, since ECDIS alarms are usually false positives

D. Shut down all bridge equipment and wait for it to reset automatically

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