[C38] Vibration

Wed Jul 8 12:21:23 EDT 2009

If your vibration is from an interaction with your prop and strut, I would
think that if you run your engine in gear while tied up in your slip, the
vibration would be there at all engine speeds though at a different
frequency, while misalignment-caused vibration might stop at low engine
speeds.

It does sound like it could be misalignment.  After major drive train work,
I've had to align my engine several times after a hull out as the boat
settles when you put it back in the water.  

How close is your prop to your hull at the top?  Did they shorten your prop
shaft or move the engine mounting?

By the way, I don't think the flexible couplings help that much with
vibration.  I've had two different kinds.  They require pretty tight
tolerances for engine alignment.

Rich West, Legacy, #360, San Diego

  _____  

From: listserve-bounces at catalina38.org
[mailto:listserve-bounces at catalina38.org] On Behalf Of Max Soto
Sent: Wednesday, July 08, 2009 7:46 AM
To: Catalina 38 Listserve
Subject: Re: [C38] Vibration

Kerry, 
I have the same prop and always had that vibration no matter how well
aligned my engine is and prop is perfect.  I don't have a flexible coupling
yet, and I think that will make a great improvement. 
 I have 1 1/4"  between the strut and the prop.  
When I just bought the boat and moved to my slip the guy that cleaned the
prop left a line on the water that no one else saw. It got caught by the
prop, bent the strut and broke the shaft, so, I also had work done on the
strut and Can't tell if there was a vibration before.

Max Soto
C38 #198 ESTANCIA
Puntarenas, Costa Rica

2009/7/8 <littlebreeze at comcast.net>

I'm sorry, I should have mentioned that the prop is the factory fixed two
blade prop.

Kerry 

----- Original Message -----
From: "Bob Porter" <hiawatha at localnet.com>
To: "Catalina 38 Listserve" <listserve at catalina38.org>
Sent: Wednesday, July 8, 2009 2:45:07 AM GMT -08:00 US/Canada Pacific
Subject: Re: [C38] Vibration

? 
Is there anything that could have changed the balance of your prop. I has a
martec folding prop with a slight imbalance and it caused quite a vibration,
dependent on speed.

Bob Porter

----- Original Message ----- 
From: littlebreeze at comcast.net 
To: Listserve, Catalina <mailto:listserve at catalina38.org>  
Sent: Wednesday, July 08, 2009 2:12 AM
Subject: [C38] Vibration

I recently had my boat in for a bottom job.  While there the strut was found
to be loose.  I had the strut repaired and now there is a vibration.  At
first the vibration was so violent to broke the hose clamps on the packing
gland hose.  Then the engine was realigned and most the vibration was gone.
The vibration which is left is still enough to vibrate the steering
pedestal.  When I bought the boat 5 years ago I brought it up the coast on
the motor and there wasn't a vibration and when I took to have the bottom
repaired there wasn't a vibration.  Now it is logical to believe that the
vibration was there you just couldn't feel it because the strut was loose
and now that it is rigid again you can feel the vibration.  The other thing
which is of concern is that the propeller is mounted within 1/4 inch of the
strut, but there is another Catalina 38 in the same yard and the propeller
is approximately 1 foot from the strut.  (of course is has been a month and
I did not measure the distance between the strut and the prop).  I think
there could be a correlation between the location of the prop/strut and the
vibration.  

So I have several questions.  First, for those of you who have had you boats
out of the water recently, what is the distance between your prop and the
strut.  Second, any Ideas on the vibration?  Third, I know some of you have
had to deal with vibrations in the past, what have you done to rectify your
problems?

Kerry Grimes
Littlebreeze, 139
San Francisco

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