[C320-list] Engine/Shaft Noise and Vibration
Dennis Harris
dharris02 at suddenlink.net
Sun Feb 20 17:46:45 PST 2011
Karl,
I didn't find the Mainsheet article, but I did find a brief write up
(perhaps a forum message that would appear to be from you on the same
subject. I downloaded it and will check out my situation. Thanks
Dennis Harris
C320 #694
----- Original Message -----
From: "Karl Mielenhausen _/)" <C320 at suddenlink.net>
To: <C320-List at catalina320.com>
Sent: Sunday, February 20, 2011 1:20 AM
Subject: Re: [C320-list] Engine/Shaft Noise and Vibration
> Dennis,
>
> My Mainsheet article
> (http://www.catalina320.com/article.php/20090227141444654) might be of
> interest. I had several similar symptoms.
> You may get lucky and discover loose jack bolts on one or more of the
> engine mounts, like I had.
>
> Karl
>
> On Sat, 19 Feb 2011 11:40:29 -0500, Dennis Harris
> <dharris02 at suddenlink.net> wrote:
>
>> Just curious if other C320 owners experience this. I get a low level
>> noise/vibration at certain speeds, and always have the fear that,
>> despite what the mechanic said, the shaft may be striking the hull, but
>> the frequency doesn't seem right. The boat is a 2000 model (#694) with
>> Yanmar 3GM30F engine and transmission with 2.21 reduction. The sound is
>> a little like a very low level "whump, whump, whump". The frequency
>> increases with engine speed, but at higher speeds, the noise is largely
>> overridden by engine noise and vibration does seem to increase
>> significantly, so it may be noise more than vibration. The cutless
>> bearing is snug and there is no movement in the shaft. However, in last
>> year's haul out, on the forward edge of shaft strut, a small crack had
>> come in hull fairing material. The three remaining sides around the
>> strut were solid and there was no leaking into the boat. The four strut
>> bolts were tight. In previous haul outs, this area was fine, and the
>> noise/vibration that I have mentioned has always been present through
>> out the 10+ years that I've owned the boat. There have been no issues
>> (abnormal, frequent wear) at the packing gland. At ~2200 rpm, the
>> intermittent sound occurs roughly 100 times/minute. With the 2.21
>> transmission reduction, this means that the sound occurs at a frequency
>> of once per 10 shaft rotations, so in my mind, I have attributed the
>> sound/vibration to be a harmonic of the combined system (hull, engine,
>> shaft, etc.) and suspect that it's something not to worry about.
>> But....what if?
>>
>> Do others experience this? Is it a problem that needs to be addressed,
>> and if so, how?
>>
>> Thanks,
>>
>> Dennis Harris
>> C320 #694, Washington, NC
>
>
> --
> Karl Mielenhausen
> Catalina 320 Hull 690
>
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