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S&S Swan Maintenance - Swan 44 knocking noise - is it the rudder?
29 July 2021 - 16:21
#1
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Simonballantine
Join Date: 26 November 2011
Posts: 7

Swan 44 knocking noise - is it the rudder?

We get a very load knocking noise when turning the rudder but this only happens when the boat is powered up and going about 8 knots.  It sounds like a machine gun!

I had always assumed it was due to the large 18" fixed propeller having too little clearance to the hull, but having just installed a smaller 4-blade feathering propeller I am still getting the same noise.

I can feel no vibration in the prop shaft, or in the rudder stock and there is no vibration in the steering wheel.  The noise in the aft cabin is very loud and seems to be coming from near the rudder.  

Any ideas ?
30 July 2021 - 09:12
#2
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the professor
Join Date: 02 January 2008
Posts: 1547

Dear Simon

You say the problem occurs when "the boat is powered up". Assume this means the engine is running at high rpms, if so, your propeller shaft is touching the stern tube.
The shaft position in the stern tube needs adjustment.
 
Kind regards
Lars
30 July 2021 - 09:51
#3
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Simonballantine
Join Date: 26 November 2011
Posts: 7

No, by 'powered up' I mean the boat is under sail in a strong wind, with lots of load on the rudder... 

The noise happens when we are above a certain speed (approaching 8knots) and when the rudder is turned, or when the rudder is being held straight (with some effort) whilst a wave or a gust is trying to turn the boat to windward..
30 July 2021 - 10:48
#4
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the professor
Join Date: 02 January 2008
Posts: 1547

Thank you for the info.

Suggest you check the steering cables, the steering sheave bearings, and the bearing at the upper end of the rudder stock
Lars
30 July 2021 - 10:54
#5
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Simonballantine
Join Date: 26 November 2011
Posts: 7

Thanks; i will do exactly that...
31 July 2021 - 11:20
#6
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PerS
Join Date: 16 December 2013
Posts: 8

Could it be a wear in the lower (delrin-)bearing in the shoe, that creates this noise?

PerS
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