Question 1

During your oral exam you are asked: when planning to anchor a yacht in a bay with an unfamiliar bottom, what factors determine the amount of anchor chain (scope) you should lay out, and why is this important?

Accepted Answer

Scope depends on the depth of water, expected tidal range (the maximum depth at high tide must be used, not the depth at the time of anchoring), holding ground type, forecast wind/weather, and swinging room available — a common guideline is 4:1 to 6:1 for chain in moderate conditions, increasing in stronger winds, because adequate scope reduces the angle of pull on the anchor, improving holding and reducing the risk of the anchor breaking out Insufficient scope results in too steep an angle of pull on the anchor shank, which can cause it to break out of the bottom under load — a common cause of vessels dragging anchor in deteriorating conditions, particularly overnight when wind picks up unexpectedly. The requirement to plan for maximum tidal depth (not current depth) is a frequent oversight that results in inadequate scope at high tide even if it appeared adequate when the anchor was initially dropped, and swinging room must also be assessed against other anchored vessels and the tidal/wind-driven swing circle, since adequate scope for holding can create a swing circle that conflicts with neighbouring vessels.

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.