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Pamkirbs
Pamkirbs

Posted: Wed Dec 21, 2011 4:51pm

Post Subject: Hot, sizzling Shaft

HELLLLLLLPPPPPPP. Firstly, I have today that I am not technical so I apologise in advance. Now, I have a problem that even the engineer is stuck on. My shaft is getting very hot and smoking after hours of sailing. 3 weeks ago I had the packing gland replaced and more recently the rudder bearing. The problems have started 3 weeks after my packing land was replaced whereby my prop gets very hot and smokey. The engineer has checked that the packing isn't too tights and you can turn the prop with your hand, the prop shaft is aligned and there is gear box oil. Now, when he changed the packing the bolt on the collar snapped and the coupling had to be taken to bits to fit new bolts on and refitted. Has anyone got any ideas what could be the matter?

Tony-B
Tony-B

Posted: Wed Dec 21, 2011 9:17pm

Post Subject: Hot, sizzling Shaft

I am assuming this is a traditional shaft assembly and that you are pushing adequate grease into the gland/bearing. First of all I can see no way a competent engineer would snap one of the bolts used to adjust the packing collar. There is no other bolts to undo to repack the gland. The fact that he did snap one suggests that he has very badly over tightened the gland at some stage so the packing itself could still be tight. However there are degrees of "being able to turn the shaft by hand". If the shaft is fairly free to turn I would suspect the engine is out of alignment and it is creating sufficient friction to heat the gland/shaft to start it seizing. Has anything been done to allow the shaft/engine to move forward (like mis-reassembling the coupling) to allow the prop to bush itself against the outboard bearing, again increasing friction. Flexible engine mounts will allow the shaft and prop to move forward when power is applied in ahead unless a thrust bearing is fitted to the shaft. If it really was the whole gland that has been replaced rather than just the packing then possibly the inboard bearing etc. is metric on an imperial shaft so may be fractionally undersized for the shaft. I have known synthetic rope and fishing line jamb between the prop and outboard bearing or actually melt inside the bearing. I think you may need another engineer because there are symptoms here that contradict each other. Tony Brooks

Pamkirbs
Pamkirbs

Posted: Sun Dec 25, 2011 5:49pm

Post Subject: Hot, sizzling Shaft

Hiya Tony, I requested another engineer to come and inspect my boat and the problem was found immediately. The packing was fitted too tight and also the engine mounting bolts had become loose causing movement of the prop. It could have easily been rectified the first time that I xalled for the engineer to fix the problem if only he had checked the bolts in the first place. Anyway, the packing has been replaced and the bolts tightened....everything now seems o be fine. Thank you for your great response x

Pamkirbs
Pamkirbs

Posted: Sun Dec 25, 2011 5:49pm

Post Subject: Hot, sizzling Shaft

Hiya Tony, I requested another engineer to come and inspect my boat and the problem was found immediately. The packing was fitted too tight and also the engine mounting bolts had become loose causing movement of the prop. It could have easily been rectified the first time that I xalled for the engineer to fix the problem if only he had checked the bolts in the first place. Anyway, the packing has been replaced and the bolts tightened....everything now seems o be fine. Thank you for your great response x

Sebastian
Sebastian

Posted: Sun Jan 01, 2012 1:23pm

Post Subject: Hot, sizzling Shaft

FYI - my tub was taken out of the water for 2 weeks, and on replacement this happened, it took ages to work out, but basicly the cutlass bearing had dried out - i loosened off the gland, let some water in and it never did it again.

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