During mooring work there were two tugboats giving help. The after boat was connected with a towing hawser which had a gantline in its end; it had been used to take onboard the tail rope on the ship’s poop deck. When the hawser was to be released, the gantline fell in the water and was sucked down and got tangled in the propeller. The propeller had adjustable pitch blades and was still rotating, even though it was not driving. The towing hawser was stretched so hard that it broke off and seriously injured a crewmember on the tugboat.
A number of similar incidents have been reported to Insjö, of which seven have been studied. Of these, most had been using heavy hawsers of the Atlas type, which sink in water. Only one used a floating hawser, and even that had been forced under the water by currents.
It seems that adjustable pitch propellers, which continue rotating even though they are not in use, commonly create currents that pull hawsers towards them. In two cases it has been judged necessary to emergency stop the propellers. In one of the cases described in Insjö there was a personal injury. All incidents required assistance from divers and caused delays and consequential costs. In two cases material damage was caused: one damaged axle bush and an oil leakage.
The above incidents lead to the following reflections:
• Propellers with adjustable pitch blades require great care to be taken since they continue rotating even when not used for propulsion.
• Heavy hawsers run a greater risk of fastening in propellers than floating hawsers.
• The risk of personal injury or material damage is evident.
BSU 607/07. Insjö 392 394 1099 1102 1766 1776 2234