Propeller Wash From Tug

31st January 2010

Propeller Wash From Tug

Initial Report

Report Text:

This incident occurred some time ago but is worth reporting to draw boat owner’s attention to the hazards of passing large harbour tugs.

A large vessel was finishing mooring operations with  tugs holding her on the berth.  As the vessel was secure an outbound ship with tug was allowed to proceed past.  A port authority patrol boat was also nearby.

A small motor boat was towing a disabled speed boat back into the harbour.  There appeared to be ample sea room for the motor boat to pass between the outbound ship and the berthing vessel and so the motor boat and tow continued with the shortest route.  However as he passed astern of the first tug the propeller wash forced the motorboat across the fairway and towards the course of the outbound ship.

The tug master alerted the ship to the problem and, after confirming it was safe to do so, reduced power to lessen the propeller wash.  The motor boat did not have sufficient power to counteract the wash effect and was spun around.  When the tug reduced power the motorboat realised the danger and continued to distance himself from the area until the outbound ship had passed and the way was clear to transit on the far side of the channel.

It is important that boat owners appreciate the enormous power of modern tugs and the considerable distances that the underwater wash will influence passing vessels.  This was reported as a near miss to the tug company and the Port Authority.

CHIRP Comment:

We spoke to the Harbour Master who was well aware of this issue. A specific warning of this risk is included in the local marine guide for leisure users. In the reported incident, the skipper of the tug was alert to the situation and was able to reduce power without prejudicing the safety of the berthing operation. In different circumstances, the situation could have been more hazardous. It was therefore completely appropriate that the incident had been reported to the Port Authority as a near miss.

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