Weird

[Norman_E]

I have a Vetus 55KGF bow thruster. I tested it on leaving the marina in Marmaris, and it was OK. Yesterday I needed to use it to swing the boat round in a confined space in Bozburun harbour in order to put someone ashore. I heard the motor run but there was no thrust so I used a burst of revs in forward to kick the boat round against the rudder, then motored back. Testing it again there was no thrust either to port or starboard and no sign that it was even disturbing the water, but the motor could be heard running.

First thought was a broken shear pin on the motor shaft. Other darker thoughts were a failed gearbox with stripped gears or a lost propeller.

I stripped it down today in a quiet bay. The shear pin is intact. Then I swam and removed the propeller, which was correctly fitted, and cleaned off some light fouling. Another longer swim was needed to put it back. I tested the gears by getting SWMBO to hold the coupling to the motor whilst I slowly rotated the prop, and found nothing amiss. After replacing the motor it is working perfectly.

In effect I have changed nothing yet it now works, Weird or what?

 

[NorthUp]

plastic bag in the prop which cleared on your passage out of the harbour?

 

[Norman_E]

plastic bag in the prop which cleared on your passage out of the harbour?

Not very likely, and although I did not fully explain it we motored for a mile or so to a quiet bay and tried it there. There was no disturbance to the water and it appeared that the motor was running without the propeller being turned. After that I sailed several miles to Sailors Paradise, where I tried it again and then stripped it down.

 

[NorthUp]

Many years ago when the UK still had a fishing fleet, a trawler got the net in the propeller out at Rockall, in very poor weather (F8 to 10). His pair trawler mate towed him towards Breasclete on Lewis, where divers were waiting. After five days towing, parting the towline several times in horrendous weather - they approached Gallan Head, a few miles short of harbour the Skipper looked out astern to find the offending net streamed out astern...
they took iton board and went back fishing.
The divers didnt know whether to laugh or cry!

 

[Norman_E]

It is possible something was caught in the prop, but in that case I would have expected the 3mm brass shear pin to have done its job, as it did a few years ago when a rope was caught up. On that occasion I found a steel replacement in the spares box, but after discovering that the broken one was brass, I went to Marmaris to source the correct material from which to cut a new one.