Propshaft alignement on Westerly corsair

[mldpt]

Having had my Corsair for 13 years now and replaced the Engine mounts a few times and the Volvo deepsea stern gland, without a problem, I am now getting an unpleasant knocking at high revs and in rough following sea i am assuming that this is the prop shaft catching on the stern tube. I know of one other Corsair which had this problem and he has cured this by putting another cutlass bearing up the stern tube and a flexable coupling into the drive, I am not sure about this as an ordinary flexable drive coupling is not designed to transmit forward thrust which drives the boat forward or astern, has any body else had this problem.
Regards Mike

 

[pvb]

Volvo stern gland...

If you're talking about the simple black rubber Volvo seal, Mike, this has a support "bearing" (rather like a cutless bearing) inside it. Because of this, I think it's unlikely that the shaft would be able to hit the stern tube at the inboard end. It's possible that the shaft isn't perfectly straight, and this could result in knocking at higher revs, as the shaft distorts inside the stern tube.

 

[boatmike]

It could be simply a knackered cutless bearing and/or a bent shaft. Obvious check for both..

 

[eyehavit]

After 13 years I reckon both pvb & boatmike nailed it. Your aftmost bearing is in need of replacement. Well worth checking shaft straightness as well.

 

[pvb]

The plot thickens...

According to another post elsewhere, Mike replaced his cutless bearing last year. So it should still be OK.

 

[Thistle]

Re: The plot thickens...

[ QUOTE ]
According to another post elsewhere, Mike replaced his cutless bearing last year. So it should still be OK.

[/ QUOTE ] ... unless there is some distortion in the shaft.