[C320-list] motor mounts

[Dave Moores]

Pat,

Yes, I have the same question.  It seems as if even though the blades are
geared together there is enough imbalance/slop to allow vibration when the
prop is not fully open when I am at low/medium RPM's and sailing as well.
In that condition there is not enough thrust to force the blades fully open.
A soon as I rev up it all smooths out.

Dave

-----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 9:02 AM
To: C320-List
Subject: Re: [C320-list] motor mounts


Why would your prop not open fully as it is geared?
I live in fresh water and will only develop slime and growth not 
animals with shells.
Can you get full RPM and is it a 2 or 3 balde?

At 07:48 AM 7/30/2007, you wrote:
>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

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