Situational awareness is the critical factor for a navigator, warns The Nautical Institute in a new Mars Report. In this report, a tug was so busy breaking ice, that the crew did not notice they were sailing into shallow water at high speed. It led to the loss of the tug.
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.
Two tugs were towing a barge in coastal iceinfested waters. At one point, tug 1 had to release the tow and go around the barge to clear the ice. Tug 2 remained attached to the barge. About 10–15 metres north of their position was a shoal area of less than 6 metres in depth.
When tug 1 had turned around in open water, it was observed that the open water lead was closing behind them. To free the barge, the crew of tug 1 decided to make a pass 5–10 metres from the barge’s starboard (southern) side before recoupling to the barge and continuing the tow.
As tug 1 made a full speed approach towards the barge, using the swell to break up the ice as much as possible, a last-minute decision was made to go to the port side of the barge instead (ie the north side).
Also read: Salvage of grounded cargo ship Meshka completed
Hard aground
Within seconds tug 1 ran hard aground at a speed of 11 knots. The grounding was violent, and the ship immediately listed heavily to port some 40 degrees. Both the master and the crew member fell out of the wheelhouse and landed on the port bridge wing. To avoid being exposed to the cold water, the master released the ship’s liferaft.
Unfortunately, the liferaft ended up upside down on the ice and could not be used. Fearing that the vessel might capsize, the crew crossed the ice to the barge, and hence to tug 2. Tug 1 was later deemed a total loss.
Investigation findings
The investigation subsequently found that tug 1’s ENC did not meet the standards for an approved electronic chart, and lacked information on the quality of the depth data. Additionally, the ENC’s setup made use of the same colour palette for depths between 3 and 10 metres. Because the tug’s draught was 4.2 metres, this setup gave no colour indication of the shoal danger.
Another weakness in tug 1’s ENC was that it had no limit on how far it could zoom in. Electronic nautical charts that are over-zoomed can lead a user to believe that the accuracy is increased to the same extent, which is not the case.
The investigators also found that the principal navigation method was to visually follow the ice channel illuminated by the ship’s headlights and the deck lighting on the barge.
Also read: Poor BRM between pilot and bridge team leads to grounding
Advice from The Nautical Institute
- In this occurrence, the tug crew’s concentration on one task, that of breaking ice and visually following the ice channel, blinded them to the impending danger. They ran aground at full speed.
- Situational awareness is the critical factor for a navigator. It cannot be repeated enough: Use all possible means to determine your position.
- The proper use of ENCs or ECDIS is critical to sharpen your situational awareness and risk appreciation. The correct safety depth and/ or colour palette selection can make the difference in grounding your vessel, or not.
Also read: Restricted waterway bank effect grounds vessel
Mars Reports
This accident was covered in the Mars Reports, originally published as Mars 202523. 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.
Picture: Tug aground and listing (all images by The Nautical Institute).
