Forums » Ask a Question

Use this forum to post your questions to our experts – you need to be logged on to do it (you can register here ), then scroll down to the bottom of this page and click the blue Post Thread words

If you can help answer the question, feel free to post a reply – you need to be logged on to do it (you can register here ), then hit the reply button on the thread.

 

To go back to the experts page click here>>

AuthorMessage
countyoak
countyoak

Posted: Mon Sep 07, 2009 2:30pm

Post Subject: Prop Shaft Noise

I have recently noticed that there is a sqealing noise coming from my prop shaft, similar to a slipping fan belt but not as loud. It only occurs around 12,000 revs. The shaft runs through an aqua drive flexible coupling. The problem does seem to have co-incided with picking up some debris on the prop which required dislodging via thw weed hatch. Any ideas?

countyoak
countyoak

Posted: Mon Sep 07, 2009 5:45pm

Post Subject: Prop Shaft Noise

Further to my post, the engine is a Barrus Shire 45, not some kind of dragster, so that should read 1,200 revs, not 12,000!

Tony-B
Tony-B

Posted: Mon Sep 07, 2009 7:27pm

Post Subject: Prop Shaft Noise

Dear Peter I am pleased you noticed the speed thing but I would have assumed it was 1200. First of all make sure that the prop is completely clear and at the same time feel around the prop blades for signs of being bent or chipped. To be honest it sounds like hydrophonic noise from the prop (sometimes called a singing prop) and it can be hard to solve. Anything that alters the way water flows around the prop can cause it, so are you on "home waters" or out cruising - it could just be a shallow canal. If it comes and goes it could be the start of leaves around the prop season. Make sure the stern gland is well lubricated if its a normal stuffing box and then use a stick as a stethoscope to try to localise the noise away from the aquadrive & stuffing box. This can be hard because sound will travel down the shaft. Also make sure the anti-cavitation plate under the weed hatch is not vibrating against the hatch trunk. Once you are sure nothing is amis try to live with the noise. If that is not possible and AT YOUR OWN RISK tweak the tip of a blade or two with a large set of adjustable spanners a little so hopefully it vibration frequency is altered. When the boat is slipped grinding the edges of the blade to remove the nicks might or might not help. Sorry not to be much help. Tony Brooks

countyoak
countyoak

Posted: Tue Sep 08, 2009 7:14pm

Post Subject: Prop Shaft Noise

Dear Tony Thanks for the advice. i did in fact notice a small chip out of the prop whan it was recently slipped for blacking,there was also some slight distortion of the blade in the same area, so that may well be the answer. I did consider trying to tidy it up but feared I might do more damage. I'll have another look next time the boat is out of the water. Thanks again Peter

Most Read

Like us on Facebook



Follow us on Twitter

Cache: Disabled for this object  Total Queries: 43.  Total Objects: 162.  Total Unserialized: 3. Total Runtime: 0.24 seconds.