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Motor Vibration

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  • Kirk Glenn, CPA
    On the 362 I am looking at between 1,200 and 1,500 rpm s there is a noticeable vibration while in gear. Below and above these rpms it is very smooth. The
    Message 1 of 2 , Sep 6, 2007

      On the 362 I am looking at between 1,200 and 1,500 rpm’s there is a noticeable vibration while in gear. Below and above these rpms it is very smooth. The engine is a 35B which is a three cylinder Westerbeake. This does not have the cv joint that my 38 MKII had. The cutlass bearing is tight and the prop is a 3 bade martec. My previous three boats had diesel engines and accept at a low rpm were very smooth through to the max recommended rpm.  Am I missing some thing ?

       

      Kirk

    • J. Scott Clinton
      vibration can be a tricky thing - you might be getting a resonant frequency. Finding and fixing that can be a nightmare and it may be easier to adjust your
      Message 2 of 2 , Sep 6, 2007
        vibration can be a tricky thing - you might be getting a resonant frequency.  Finding and fixing that can be a nightmare and it may be easier to adjust your RPMs.  On my 28, I find a resonant frequency at about 1/4 throttle (atomic 4 engine - I don't know the RPMs as hull #11 wasn't delivered with a tachometer).  The vibration is generally found in the stove cover - just very loud.

        This throttle setting results in about 3 knots in still water and I generally make a small adjustment (either higher or lower) and eliminate the vibration that way.  Could I chase down the issue and fix it?  Probably, but there are other things that I would rather work on.

        my $.02.

        J. Scott Clinton
        Hull #11.

        On Sep 6, 2007, at 12:42 PM, Kirk Glenn, CPA wrote:


        On the 362 I am looking at between 1,200 and 1,500 rpm’s there is a noticeable vibration while in gear. Below and above these rpms it is very smooth. The engine is a 35B which is a three cylinder Westerbeake. This does not have the cv joint that my 38 MKII had. The cutlass bearing is tight and the prop is a 3 bade martec. My previous three boats had diesel engines and accept at a low rpm were very smooth through to the max recommended rpm.  Am I missing some thing ?

         

        Kirk



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