[C320-list] motor mounts

[Pat Moriarty]

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