Question 1

During your oral exam you are asked: your vessel's AIS is displaying a target with information (vessel name, dimensions, destination) that appears to conflict with what you can observe visually and by radar (e.g. the AIS shows a small vessel but radar/visual shows a much larger one in that position). What should you consider?

Accepted Answer

AIS data is self-reported by the transmitting vessel and can be incorrect due to data entry errors, outdated information, equipment faults, or in rare cases deliberate manipulation; if AIS information conflicts with radar/visual observation, prioritise the information from radar and visual observation for immediate collision avoidance purposes (actual position, course, and speed as observed), while treating the AIS-derived identity/characteristics information with appropriate caution AIS data quality depends entirely on what has been entered into the transmitting vessel's system and the proper functioning of that system — static data (vessel dimensions, name, destination) is manually entered and can be outdated or simply wrong, while dynamic data (position, course, speed) depends on the transmitting vessel's own sensors. For immediate collision avoidance decisions, the watchkeeper's own radar and visual observations of the target's actual behaviour represent ground truth and should take priority if there is any conflict, while AIS remains valuable for identification and communication purposes (e.g. calling a vessel by name) — over-reliance on AIS data without independent verification has been a contributing factor noted in some near-miss reports.

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.