Visual navigation in fog is a recipe for an accident. The Nautical Institute gives this warning in its latest Mars Report, in which a cargo vessel grounded while under pilotage.
The Nautical Institute gathers reports of maritime accidents and near-misses. It then publishes these so-called Mars (Mariners’ Alerting and Reporting Scheme) Reports (anonymously) to prevent other accidents from happening. This is one of these reports.
A loaded cargo vessel was outbound under pilotage in daylight and moderate visibility. A tug was in attendance, but was released once the vessel was past the port breakwaters. About seven minutes after the tug departed the vessel, visibility unexpectedly reduced to about 200 metres. The vessel was at a speed of six knots, and over the next two minutes, the pilot gave helm orders to make a 44 degree port turn out to sea (see diagram).
The vessel turned further to port than desired. Once the pilot realised this, he gave starboard helm orders, but it was too late. The vessel grounded outside the buoyed channel about four minutes after the first port helm order was given. Attempts to use ship’s power to return to the channel were fruitless and salvage tugs were needed.
Also read: Ferry trip ends with U-turn into shore
Investigation findings
The investigation found, among other things, that the vessel lacked a complete voyage plan to exit the harbour (ie courses, safety distances, clearing bearings, rate of turn etc.) and that the pilot was navigating primarily by visual means. When the visibility unexpectedly reduced, the bridge team were at a disadvantage. No one on the bridge was in control of the progress of the 44 degree port turn by electronic means such as ECDIS or radar.
Also read: Ferry grounds after narrow port entry proves too tricky in near zero visibility
Advice from The Nautical Institute
- A shared plan is a safer plan. In this case, the plan was in the pilot’s head, much as we saw in Mars 202153.
- Even with a pilot on board a master should ensure courses are put on the chart or ECDIS and officers of the watch (OOWs) are closely following the progress of the vessel.
- Visual navigation in fog is a recipe for an accident.
- When in doubt, slow down if possible. In this case, the vessel was at six knots, which is not that fast – except they didn’t have good situational awareness. At 4 knots, they would have had fifty per cent more time to evaluate.
Also read: Fog and single-point failure lead to allision with bridge support
Mars Reports
This accident was covered in the Mars Reports, originally published as Mars 202433, that are part of Report Number 380. A selection of the Mars Reports are also published in the SWZ|Maritime magazine. The Nautical Institute compiles these reports to help prevent maritime accidents. That is why they are also published (in full) on SWZ|Maritime’s website.
More reports are needed to keep the scheme interesting and informative. All reports are read only by the Mars coordinator and are treated in the strictest confidence. To submit a report, please use the Mars report form.
