Question 1

During the current S-57/S-101 transition period, what is a genuine, practical risk bridge teams should plan for on a long passage?

Accepted Answer

Mixed-format passage planning, where different legs of a voyage may draw on charts in different formats, requiring confirmation of which format applies to each leg rather than assuming consistency Hydrographic offices are producing ENCs in both S-57 and S-101 formats in parallel through the 2020s, with S-57 expected to be phased out only in the 2030s. A long passage can genuinely cross areas covered by different chart formats, and confirming which format actually applies to each leg — rather than assuming uniformity — is a real, current planning consideration.

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.