[C320-list] Vibration under power issue

[jim brown]

There are 2 good articles on the 320 site on shaft alignment. I think Jeff Hare posted one and it comes complete with a spread sheet with measurements. 

Jim Brown


      From: Chris Burti <clburti at gmail.com>
 To: 320 <C320-List at catalina320.com> 
 Sent: Wednesday, July 27, 2016 3:52 PM
 Subject: Re: [C320-list] Vibration under power issue
   
Alignment can be a bit trickier than many yards realize.
The first rule is that it has to be done with the boat in the water and at
least couple of days after being put back in the water so that the hull has
had a  to settle back into its normal shape.

Second rule is that the alignment has to be done four times with the
coupling faces sequentially rotated at 90 degree intervals to be assured
the the couplings are installed perfectly square on their respective
shafts. If they are not (and that is not uncommon), you can't truly align
the shafts and you will not be successful in getting vibration reduced to a
minimum.

Squaring the couplings on either of the shafts, if required, is a job for a
machine shop requiring a haulout.

CB
Commitment, #867

Chris Burti
Farmville, NC


On Wed, Jul 27, 2016 at 3:36 PM, MSail <msail at baymoon.com> wrote:

> I'd appreciate any feedback from the fleet regarding a vibration issue
> that arises above about 2000 engine rpm.
>
> 1996 C320
> Westerbeke 30B
> JS Transmission
> 16" Max Prop (3-1/4" clearance tip to hull)
>
> Problem:  In gear, vibration/rattle above 2000 rpm, increasing further as
> engine speed increases to maximum.    Engine and transmission moving
> considerably on mounts when vibration is encountered. In neutral, engine
> runs smoothly to max rpm, no vibration.
>
> I've replaced:
>
> Engine mounts (with Westerbeke OEM original types)
> Prop shaft (from original bronze to Aquamet 22)
> Cutlass bearing (replaced 2 years ago, showing some wear as of 7/16 but
> not deemed excessive)
> Done careful shaft-transmission coupler alignment with yard.
>
> Have NOT replaced damper plate.
>
> Thanks in advance for comments.  Has anyone else on this list experienced
> this problem with this setup?
>
> Michael  Mellon
> Santa Cruz, CA
> msail at baymoon.com
>