[C320-list] A High Pitched Whine Noise

[Chris Burti]

Your symptom sounds very much like prop harmonics. While there does
not seem to be any rationale in it appearing after a simple cleaning,
I have heard of it happening in one other instance and a light
flattening/rounding of the leading edge cured the whine.

While alignment is more likely to cause vibration than whine, accepted
wisdom is that alignment should be done after every haul out and
particularly after a land delivery

On Fri, Sep 10, 2010 at 12:57 PM, Utility Email <kswanson123 at comcast.net> wrote:
> We after trucking out C320 all the way from San Diego to Seattle, spending a week in the Seattle boatyard repainting the bottom, waxing the hull, and inspection restepping the rig, our beautiful boat is back in the cool waters of Puget Sound.
>
> However, we also have a new sound...
>
> When motoring between, say 1800 and 2200 RPM, there is a high pitched whining sound coming from the shaft area.  The noise is more like a high pitched whistling or whining sound. The sound is very high pitched and sharp in tone.
>
> After doing a list-server search, I read somewhere that it could possibly be a high pitched harmonic with our stock 3-bladed propellor and a "fix" could be to "dull" the leading edges of the blades. I'm not sure that I buy this explanation/fix without other input, but I am at a loss for another rational explanation.  Hence, this is why I am inquiring through our C320 list server.
>
> We never heard this sound before in our C320 after operating the boat for the last year, or any other boat we have had.  Has anyone else experienced this type of noise coming from the drive train area?
>
> A couple of other facts about some basic changes to the boat from San Diego to Seattle:
>
> 1. We cleaned the prop and applied 3 coats of Petit (barnacle buster) zinc paint to the brightly cleaned bronze 3-bladed prop during our recommissioning in Seattle. The prop was cleaned with vinegar and a wire brush to a bright metal finish, no filing or edges of the prop were sharpened in the cleaning process.
>
> 2.  I cleaned out the stock flax shaft packing and installed 2 rings of new 1/4" Gore Tex GFO packing. I adjusted the drip rate to about 3 drips per minute under power, and we still get high pitched sound.
>
> 3.  I have not checked the engine and shaft alignment yet. I am thinking of hiring a mechanic to check and realign the shaft to the engine since the boat was transported from SAN to SEA by truck.  Do others agree that the engine and shaft should be aligned after overland trucking of the boat?
>
> 4.  New zincs are installed on the propellor shaft and strut. I doubt this has any affect.
>
> 5.  Yesterday we motored for about 5 hours to transit the boat from the Seattle-based boatyard to our home marina. The high pitched sound was present when we started and also when we arrived at our marina.
>
> 6.  The engine has about 100 hours on it and it has been well taken care or and services regularly.
>
> If the sound doesn't indicate that there is nothing mechanically wrong with the boat or drivetrain, then it is just an annoying sound that I will avoid while operating the engine.  If not, then I would like to learn about what I should do to fix it.
>
> Any and all comments, advice, and/or a fix would be appreciated.  Please weigh in with your experience.
>
> Thanks!
>
> Dave Swanson
> S/V Emily Ann
> 2007 C320 MK II, No. 1107
> Mukilteo, WA
>
>



-- 
Chris Burti Farmville, NC