[C320-list] Prop shakes

[Peter Clancy]

Dave ...... I didn't realize the prop was 11 years old. I suppose its possible that the moving parts of the prop have by now worn down a bit creating excess tolerances. I'd suspect two things ..... the pins that hold the props in place and the surfaces where the blades move in and out of position. I believe Martec can 'restore' their props but not sure about Gori.

Pete Clancy
  ----- Original Message ----- 
  From: Dave Moores<mailto:dmoores at cogeco.ca> 
  To: 'C320-List'<mailto:c320-list at catalina320.com> 
  Sent: Thursday, October 18, 2007 11:52 AM
  Subject: Re: [C320-list] Prop shakes


  Thanks Peter, the boat(and prop) are now 11 years old and I notice a fair
  amount of "slop" in the fore and aft direction when I move the blades around
  with the boat out of the water. I also had a new cutlass-bearing installed a
  while back, which appears to have hard-rubber flutes as the bearing surface,
  and I wonder if that is allowing the prop to shake the shaft around more
  than a solid bearing would do?

  As I mentioned, the problem only occurs when I am at below 2000 revs.
  Everyting smooths right out, after a few moments of nasty shaking, once I
  open the throttle.  This makes me think that the small amount of slop is
  allowing enough imbalance to occur with a partly-unfolded prop, eben though
  the baldes on the Gori are geared-together to avoid assymetrical unfolding.

  But that is just my guess and anybody else's experiences would be welcome. 

  Dave M

  -----Original Message-----
  From: c320-list-bounces at catalina320.com<mailto:c320-list-bounces at catalina320.org>
  [mailto:c320-list-bounces at catalina320.com] On Behalf Of Peter Clancy
  Sent: October 18, 2007 11:33 AM
  To: C320-List
  Subject: Re: [C320-list] Prop shakes


  I installed a Gori 2-blade folder three years ago on 'AROBAN' and never
  experienced vibration problems.

   I understand that Gori props are precisely balanced when manufactured so
  it's unlikely the prop itself is the problem. A loose cutlass bearing or a
  warped shaft could be the culprit. However, incorrect installation of the
  prop is also a common cause. For example, it's critical to 'mate' the
  propellor to the shaft by eliminating any out- of- roundness between the two
  mating surfaces. This is done with valve grinding compound and by spinning
  the prop on the shaft until it turns smoothly. The other step is to assure
  the prop is set fully back on the shaft. It's possible for the key to jam in
  the keyway as the prop is pushed on to the shaft thus preventing it from
  seating firmly. 

  Peter Clancy
  'AROBAN'  C320  #222 (former owner)
  Miami, FL



    ----- Original Message -----  
    From: Pat Moriarty<mailto:patm at psiurethanes.com<mailto:patm at psiurethanes.com>> 
    To: C320-List<mailto:c320-list at catalina320.com<mailto:c320-list at catalina320.org>> 
    Sent: Thursday, October 18, 2007 10:15 AM
    Subject: Re: [C320-list] Prop shakes


    Machine what? Mine did it brand new but gets worse at RPM and I had a 
    new cutlass bearing .

    Pt #130

    At 08:55 AM 10/18/2007, you wrote:
    >My Gori two-blade has started shaking and rattling at intermediate
    >engine-speeds.  It smooths out fine once I rev up.
    >
    >My mechanic says he sees this a lot and it "needs machining".
    >
    >Anybody had a similar situation?  Did machining fix it?  Any other
  advice?
    >
    >Dave Moores

    Pat Moriarty
    PSI Urethanes Inc
    PH: 800-888-5156  Fax: 512-837-8733
    Please visit our web site at
    www.psiurethanes.com<http://www.psiurethanes.com/<http://www.psiurethanescom%3chttp//www.psiurethanes.com/>>