[C320-list] noise

[Rick Sulewski]

I concur with Chris.  Put an edge on the prop blades. I have the same whine
this year and used some rough grit sandpaper to clean up the prop - a
mistake as I have whine that I may reduce by changing the engine speed
(slower or faster)

I will use a file to replace the square edge that may have been reduced with
the sand paper.

My-Ria 277

-----Original Message-----
From: c320-list-bounces at lists.catalina320.com
[mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Chris Burti
Sent: Wednesday, September 03, 2008 10:16 PM
To: C320-List at catalina320.com
Subject: Re: [C320-list] noise

If you have a fixed bladed prop, I have a guess as to the cause of your
problem. Sometimes when the blades have been finished too sharply, they
produce a noise that can be described as whistling. It is some form of
harmonic resonance and as the noise is transmitted up the shaft and strut,
it is loudest in the lazarette. I don't know the physics of it, but whenit
is the cause, taking a file and dulling the leading edge of all blades
uniformly will make the noise ddisappear.


On Wed, Sep 3, 2008 at 8:58 PM, jim brown <jbrown5093 at yahoo.com> wrote:

> Was motoring to Kingston Ontario yesterday and about half way there (12
> miles) noticed a whistleing noise at about 2200rpms. Seemed to go away at
> 2800 but could be heard at lower rpms. It was hard to pinpoint but I
removed
> the front and real engine covers and heard nothing, checked the shaft and
> packing gland nut which was cool and leaking normally. The transmission
was
> quiet. I opened the rear lazarettes and the whistle/warble was quite loud.
> Went into the compartment and it seemed to be coming from the bottom area.
> While sailing back home today I left the tranny in neutral and there was
no
> noise. It also doesn't happen in reverse. Could this be the sound of a
> failing cutlass bearing or are there other possibilities. Hull 978 with
200
> hours on the engine. Desafinado will be hauled in 2 weeks for the winter
but
> I was wondering what to expect or have checked over the winter lay up.
> Thanks for any help.  Jim Brown
>
>
>
>


-- 
Chris Burti Farmville, NC