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1406Re: [j4x-owners-group] J42 Propeller shaft strut alignment

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  • Thomas Keffer
    Apr 9, 2014
      Could definitely be an alignment issue. Normally, when an engine is aligned, you put the boat in the water, let it settle for a day, then do the alignment. 

      It could also be a bent shaft, bad cutlass bearing, bad engine mount, or a bad prop. The surveyor should have checked for a bad bearing and bad prop, but the others might be tough to spot in a survey. Also, it wouldn't explain why all was well in your sea trial.

      Take a look at your engine mounts, then try an alignment. That would be the least expensive solution. 

      I agree with Bill that these boats are meant for sailing, not motoring. Mine vibrates too. Not an obvious, something-is-wrong vibration, just a low-level throb that's a little short of annoying. 

      Oh, BTW, if it's useful, you can have my old Martec prop. It's been sitting in my basement for 7 years.

      I love this time of year! Spent yesterday crawling around the boat getting ready for the season!


      On Wed, Apr 9, 2014 at 5:22 AM, Barry Dwyer <bdwyer@...> wrote:

      On this same topic, last October we purchased #53. During the sea trials the engine ran smooth and there was no vibration all the way to WOT. The boat had been on the hard for a year, was splashed for the sea trials, and then hauled again that afternoon. Again, no noticeable issue with vibration.


      Fast forward two weeks and the boat is relaunched for the delivery down to Annapolis.  Transiting the river down into the Gulf of Maine everything was fine until we went above 1800 RPM. At that point there was vibration that sounded like something on the prop. Backing down had no effect. As the boat was able to make 6.5 knots at 1800 we decided to continue the trip. There was one other factor; when you put the engine in forward there was a loud clunk associate with the prop opening. Not the normal Martec clunk but rather a cringing expensive sounding clunk.


      So, put it in gear, loud clunk, 1000-1800 rpm all is well, 1800+ vibration. 


      This winter I sent the prop back to Martec. They said they had serviced it in the past and the pin was now the largest they could go but they did their best to recondition it.


      Last week when I launched the clunk was less noticeable but I still had the vibration above 1800 rpm.


      So my question is, could this be an engine alignment issue? Maybe something to do with being on the hard for a year?


      Having just spent a lot of boat bucks I don’t want to buy a new prop if there is some other solution.








      From: j4x-owners-group@yahoogroups.com [mailto:j4x-owners-group@yahoogroups.com] On Behalf Of Thomas Keffer
      Sent: Tuesday, April 08, 2014 11:42 PM
      To: j4x-owners-group@yahoogroups.com
      Subject: Re: [j4x-owners-group] J42 Propeller shaft strut alignment





      It's completely normal to have to realign the engine as its mounts compress over time. If the problem is the strut, it was either installed incorrectly in the first place (unlikely if you've put 1500 hrs on the engine), or it was hit. 


      This should be something you can judge for yourself. Just run something straight --- a broomstick, pipe, or even a piece of string --- from the engine, through the seal and strut. It should all be straight. A laser can also do the job.





      On Tue, Apr 8, 2014 at 8:26 PM, William Stellin <wstellin@...> wrote:


      Normally the alignment is done at the engine not the strut. The engine mounts all have bolts which can raise or lower each corner of the engine.  I wouldn't touch the strut.  It is glassed in and it would be  huge job shimming it.  Having said that, maybe it was hit and is bent out of alignment.  In that case it would have to be fixed.

      Bill    #6

      Sent from my iPad

      On Apr 8, 2014, at 10:13 PM, johnrpotter@... wrote:


      Hi all, after 1500 hrs on the engine, the cutlass bearing needed replacement.  When we removed the prop shaft it had been badly galled and needed replacement as well.  When we pressed in the new cutlass bearing, we found the prop shaft out of alignment  with the shaft tube and transmission flange. The yard thinks I need to re - shim the strut.to bring it into alignment with  the shaft tube and transmission flange.  has anyone done this on a J42 or have any suggested options?


      John Potter #57


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