Awful noise.

[Robin]

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Not sure this would work on a Max Prop as the blades are not shaped and are much thicker than on a conventional prop. My feathering prop also makes a noise at certain revs, but it is not under an aft cabin and is drowned out by lots of other noises. Volumious aft cabins tend to amplify any stern gear noises.


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The blades have probably been sharpened by all the motoring, 2000hrs in two years! Still it is a HR not a sailing boat. /forums/images/graemlins/wink.gif

We bright polish our Brunton prop and a couple of times it has had a liitle sing song immediately after re-launching but it has never lasted more than just the first trip. These days I wet/dry across the trailing edge as part of the polishing and it doesn't happen.

 

[Inselaffe]

Could it just be that something structural is resonating at certain frequency?
i.e. not anything exactly wrong with engine etc, just that a panel for example has a natural freq near the engine vibration frequency at certain revs?
If so then damp the offending panel or whatever?
Not sure if this makes sense but worth thinking about problem from another angle?

 

[bob234]

Strongly recommend he speaks to Darglow (UK Maxprop distributors) for advice. They are very helpful and I certainly wouldn't want to take a file to that lovely prop until you have spoken to them. The Maxprop doesn't have flat blades, there is shaping, but not in the same way as a fixed prop of course, but it's too expensive to mess around with without advice IMO.

Darglow would also be able to advise whether they concur with the radius and the pitch setting done by HR. We once had a problem (different one) with our Maxprop when the pitch was mistakenly re-set. Out by only one setting but boy, did it make a difference! Darglow were superb.

Cheers,

Bob

 

[Scotty_Tradewind]

You mention rudders making a noise Vyv. I was involved in Rowing. One of our new 8's had a 'singing' from the stern from new when the crew were rowing at a certain speed. Around 10-12 knots I guess.
We narrowed it down to the fin underneath, just behind the cox's seat.
We changed it for a thicker/stiffer version which was slightly aero/ or is it hydro-dynamically shaped- no noise at all.