BSafe Case Study 18 — The Chart Showed the Shoal. The Alarms Never Fired.

An Amendment Approved Before It Was Finished

Before departure, the master asked the second officer to amend the passage plan using the owner's weather routing service recommendations. The amended plan was presented to the master for approval — while still incomplete. It passed 0.3nm from a charted shoal.

The second officer's pre-departure ECDIS settings form recorded safety depth and safety contour at 20m, shallow contour at 15m, deep contour at 50m, and a danger detection sector of 5.0nm across the bow. Each leg's default cross-track limit was set at 0.50nm — wider than the 0.3nm margin the amended route actually left against the shoal.

The OOW Asked the Right Question, Then Moved On

At 0800, once on passage, the chief officer handed the watch to an additional second officer serving as OOW and left the bridge. Throughout the watch, the master, chief officer, and the other second officer all came and went, using the bridge for various administrative tasks. At one point the OOW mentioned to the second officer, who was calculating bunker requirements, that he couldn't get a line of position from a charted feature ahead — 0.30nm north of track. The second officer told him it was a shoal, to keep clear.

The OOW interrogated the ECDIS feature. He did not check whether its depth was safe against the ship's own draft (4.85m forward, 7.44m aft). He then turned to preparing arrival documents for the next port. The vessel began drifting to port, undetected. At 1155 it crossed the 5.0m depth contour and grounded.

What the Investigation Found

• The passage plan amendment was approved by the master while still incomplete, leaving a track only 0.3nm from a charted shoal.
• The ECDIS cross-track limit (0.50nm) was wider than the actual margin the amended route left against the hazard — meaning the alarm most likely to catch this exact drift was set looser than the risk required.
• No audible or visual warning was given to the OOW as the vessel drifted off track — despite settings nominally being in place.
• The OOW identified the charted shoal and asked about it — a genuinely good watchkeeping instinct — but didn't complete the check by confirming depth against draft before returning to admin work.
• Multiple officers used the bridge for non-watchkeeping tasks during the same period the vessel was drifting, without any one of them owning the developing situation.

Recommended Actions

Not invented — the direct implications of what the investigation found:

1. A passage plan should never be approved while incomplete — an amendment that changes the route's proximity to a hazard needs the same scrutiny as the original plan, not a faster sign-off because it’s ‘just an update.’
2. ECDIS safety settings — safety contour, XTL, DDS — need to be checked against the specific route being sailed, not left at a default that happened to work on a wider-margin leg elsewhere in the voyage.
3. Identifying a charted hazard and asking about it is the right instinct — but the check isn't finished until depth is actually confirmed safe against the vessel's draft, not just visually noted and moved past.
4. Bridge administrative tasks are real work that has to happen somewhere — but not at the expense of a single person clearly owning the watch at the moment the vessel is closest to a charted hazard.

Human Element Analysis

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Related Reading

• The Meshka Grounding — another real ECDIS/passage-planning gap, a different registry, the same underlying lesson
• S-100 ECDIS: what's actually changing and where crews get caught out