Question 1

You're OOW in busy coastal waters and a target vessel's AIS shows a safe CPA/TCPA. Per Gard's guidance on AIS-assisted collisions, what should you do?

Accepted Answer

Cross-check the AIS picture against systematic radar plotting and visual observation before treating the situation as safe Gard's guidance is explicit: AIS should support, not replace, radar plotting and visual observation. A safe-looking AIS CPA/TCPA is not sufficient on its own — several real collisions happened with a seemingly clear AIS picture because the underlying sensor data was inaccurate or the other vessel's AIS wasn't transmitting at all.

Question 2

You're preparing a passage plan for a coastal leg in a yacht drawing 3.2m. At one point the chart shows a least depth of 3.8m at chart datum. What MUST you check before finalising this leg?

Accepted Answer

The tidal height at the time of transit to confirm sufficient under-keel clearance Charted depths are referenced to chart datum (often LAT), so you must add the predicted tidal height for your transit time to get the actual depth, then compare to your draft plus a safety margin to confirm UKC.

Question 3

During your watch the ECDIS gives a "safety contour crossing" alarm. What is the correct response?

Accepted Answer

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 A safety contour alarm indicates the vessel may be approaching water shallower than the set safety contour. It must be investigated against the route and charted information, with avoiding action taken and the Master informed as appropriate — never simply silenced.