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Old 04-05-2016, 12:41   #16
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Re: Minor wobble of prop shaft

Originally Posted by tinkrman69 View Post
check the cutless or strut bearing first as that can be done in the water.


Engine mountings can sag over time or one could even be detached which isn't unknown. If you think about the drive, all the thrust from the prop is taken on the engine mounts in most installations.

With a set of feeler gauges undo the shaft coupling to gearbox and see if they are aligned vertically and horizontally. However, this assumes the cutlass bearing is in good condition or you are on a hiding to nothing. There are some good articles here:

Replacing Motor Mounts & The Obstacles Photo Gallery by Compass Marine How To at

BTW all cutlass bearings are not made equal and the cheapest may not be the best. In addition cutlass bearings are available either with Polyurethane which is good for wear resistance or Nitrile which has better resistance to oils and has less expansion due to water absorption.


Moody 31 - April Lass
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Old 05-05-2016, 08:19   #17
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Re: Minor wobble of prop shaft

If you can see it, it's too much.
If you don't have a dial indicator, disconnect the drive flange and use a feeler gauge to get it as close as you can, by blocking the shaft at it's 'mid point' and then adjusting the engine mounts. If you have low mechanical aptitude ( this LMA is a newly discovered disease, soon to be the subject of generous governmental subsidies!), get some competent help. It'll be a great investment.

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Old 05-05-2016, 13:22   #18
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Re: Minor wobble of prop shaft

That mid point mentioned above is when the prop shaft is centered in the shaft log. and the LMA disease......well that is a societal disease caused by domineering individuals that think too highly of themselves. the same disease women have been afflicted with for centuries. with statements like , That's a Man's job, your a woman you can't do it.

Everything is commonsense. sit down and observe. look what happens, say, when you turn on thing that is connected to another. No one, baring certine handicap's, can "not" learn something...anything for that matter. All it takes is an honest desire to learn it. With that desire, everything you need to learn something will be there. When someone comes along and tries to push you down, with negativity, forgive them and move on to someone who will give their knowledge to you.

I'm an 8th grade dropout. not to mention in a Florida school system of the '60's. I can rebuild gas and diesel engines, repair a sewing machine,build with Fiber glass, build computers, repair rigging, lay block.....I've had no school for these things and many more. But I didn't hesitate to ask questions and give it a try. sure I made mistakes, but I learned and got it right the next time. Every invention was preceded by failure. Live life
and learn...That is the Great investment.

So to all those who ask questions here and those that are too afraid to ask. there are a lot of knowledgeable people here. Take thankfully of the knowledge they freely give. It's a gift.

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Old 05-05-2016, 13:52   #19
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Re: Minor wobble of prop shaft

Lance raises a good point: Take a mechanic's course in diesel maintenance. Our club had an annual presentation by the Perkin's dealer N.A. about how to do basic diesel repairs for cruisers. Weekend course. Paid off handsomely many times when our engine appeared to give up the ghost. They really are simple engines, and with the right tools, are fairly easy to work on(If you got the space).

Which raises a piece of advice: In choosing a boat, make sure there is enough room to get to all parts of the engine. Some boats like the older Hinckleys are impossible to work on with the engine housed in very tight quarters. Hans Christians use to have the engine by the galley and you could literally uncover the entire engine. Cheoy lee put a lot of their engines deep into the bilges. That is a bad, bad idea. The Fishers located their engines right under a large sky light so the engine could be lifted straight out of the boat without much fuss.
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Old 19-05-2016, 03:28   #20
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Re: Minor wobble of prop shaft

Had this pro blem. Turned out it was soft engine mount. Also check prop balance.

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