[C320-list] motor mounts

[Dave Moores]

Pat,

I think mine is the same size...but your problem does sound different, as
mine is fine at higher RPMs, and only shakes when it is (presumably) not
fully open at lower RPMs.

Only one other thought.  My problem seemed to get worse after I had a new
strut bushing which has the rubber flutes inside as the bearing surface.  I
am wondering if this has a bit more "give" that allows the vibration.

Dave M

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Pat Moriarty
Sent: July 30, 2007 8:20 AM
To: C320-List
Subject: Re: [C320-list] motor mounts


My prop is new and it is ok at low RPM but bad at higher RPM and I 
have a new strut bushing. What is your prop 15X10?

Pat #130At 08:41 AM 7/28/2007, you wrote:
>Tha would be the Gori prop.
>
>Mine does it when not fully open and I'm just idling along.  Once up to 
>full RPMs it's fine. I'm told it needs a rebalancing and/or re-bushing 
>job.  The mechanic said "We see this all the time".
>
>My prop is presumably as old as the boat though.  Is yours brand new?  
>A brand new one ought not to shake.
>
>Dave M
>
>California Girl #342
>
>-----Original Message-----
>From: c320-list-bounces at catalina320.com 
>[mailto:c320-list-bounces at catalina320.com] On Behalf Of Robert E. Sloat
>Sent: July 27, 2007 11:54 AM
>To: C320-List
>Subject: Re: [C320-list] motor mounts
>
>
>Your new propeller may be too far aft on the propeller shaft.  I was 
>told by my Autoprop dealer that the maximum distance from the front of 
>the propeller hub to the strut should be no more than 1.5 inches.  When 
>I installed my Autoprop, the installed distance was at 1.5 inches.  
>Your flex coupling probably added one inch to this distance from the 
>OEM propeller to the strut and I assume the Gori is heavier than the 
>OEM propeller you replaced which may cause the shaft to wobble from 
>possible extra weight farther aft on the propeller shaft.  
>Unfortunately, you may have to do the measurement checking on the 
>tarmac.
>
>Some folks talk about replacing the brass OEM propeller shaft with 
>stainless.  They say the latter has less flex.  I don't know.
>
>When I installed my Autoprop propeller it seemed heavier than the OEM 3 
>blade propeller and I should have weighed both but didn't.  One season 
>and no increased vibration over the OEM propeller.  The one spot on 
>engine RPM where a little more vibration was present before the new 
>propeller was installed moved to a a slightly different RPM.
>
>Check with Gori to see if the 1.5 inches is critical for their 
>propeller and if the over pitching problem can cause vibration which I 
>doubt.
>
>Bob Sloat
>Savannah Hull #894
>
>----- Original Message -----
>From: "Pat Moriarty" <patm at psiurethanes.com>
>To: <c320-list at catalina320.com>
>Sent: Thursday, July 26, 2007 9:01 AM
>Subject: [C320-list] motor mounts
>
>
> > Hello out there does anyone have any hints on this problem?
> >
> > I have switched from the 3 blade fixed to a Gori 2 blade folding and 
> > picked up lots of vibration. In trying to sort it out engine mounts 
> > came up and while underway I checked the shaft and sure enough there 
> > is lots of engine shake and shaft wobble. Question is since it did 
> > not exist before (it was so smooth before it was like electric) is 
> > the prop shaking the engine or the engine shaking the shaft. How do 
> > you test the motor mounts? I also have a flex coupling so shaft 
> > alignment is not as straight forward as standard and not as 
> > important. As found by users in the past Gori also over pitched this 
> > prop, I get hull speed at 2500 and can not get 3000 RPM out of the 
> > Perkins.
> >
> > Pat #130
> >
> > Pat Moriarty
> > PSI Urethanes Inc
> > PH: 800-888-5156  Fax: 512-837-8733
> > Please visit our web site at
> > www.psiurethanes.com
> >
> >

Pat Moriarty
PSI Urethanes Inc
PH: 800-888-5156  Fax: 512-837-8733
Please visit our web site at
www.psiurethanes.com