Powerful tugs can create strong propeller wash currents. A tanker recently ran aground as it was passing two tugs pushing on the side of a berthed vessel.
The incident was covered in a recent Mars Report (number 201954). A transcript of what happened:
A partially loaded tanker was in a river, outbound for the sea at about four knots. A river pilot was at the con and an escort tug was secured aft. The bridge team also included the master, a helmsman and an officer of the watch (OOW).
As the tanker passed a berth to starboard where two tugs were pushing on the side of a berthed vessel, the bow of the tanker swung quickly to port. Helm and engine compensation manoeuvres had little effect and the vessel touched bottom, coming to a stop.
Thirty minutes later the tanker was refloated with the help of the escort tug and another tug. No structural damage was incurred.
Company Investigation
The subsequent company investigation and analysis of voyage data recorder (VDR) data showed no anomalies of ship equipment or helm orders. It would appear that the propeller wash from the two tugs assisting the berthed vessel to starboard was enough to push the
tanker’s bow to port and cause the grounding.
Preventative Measures
To prevent such accidents from happening, prop wash should be minimised when passing close, especially in restricted waters. To achieve this, pilots should communicate with each other before passing. At the very least, the possible occurrence of prop wash needs to be taken into account by the bridge team.
Mars Reports
This accident was covered in the Mars Reports, originally published as Mars 201954, that are part of Report Number 323. A selection of this Report has also been published in SWZ|Maritime’s October issue. The Mars Reports are also published on SWZ|Maritime’s website to help prevent maritime accidents.
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.
