201954 Tug prop wash pushes tanker aground

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 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. 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.

 

Lesson learned
Be aware that powerful tugs can create strong propeller wash currents. If your vessel passes close by these should be minimised (pilot to pilot communications) or taken into account (bridge team communications) if in restricted waters.