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-   -   vibration on increased revs (http://www.sailnet.com/forums/gear-maintenance/51020-vibration-increased-revs.html)

cheoylee43 01-31-2009 04:37 PM

vibration on increased revs
 
Our cheoy lee 43 motorsailer runs beautifully at 1500 to 1800 revs , any more we get a vibration which could be cavitation ?? or the cutlass bearing ??does Can any one suggest what to look for ?:confused:

Rockter 01-31-2009 05:16 PM

cheoy :

On my own ship, over the years I have noticed a few revs... and they are few... where the motor tends to be smoother. At some revs, the ship vibrates and the compass pedestal in particular notices it. I have learned to live with it. It's hard to tell the degree of vibration you complain about.

Take your motor revs up until it is at its worst, then send a man below to see what might be doing it. You might see something then.

FarCry 01-31-2009 05:38 PM

How clean is the prop? Did the vibration just suddenly appear or is it something that has been slowly getting more pronounced over time?

For Rockter's enjoyment-----Check for a missing fuel return line.:D :D :D

Rockter 01-31-2009 07:04 PM

Farcry :

I hope your engine mounts get splashed with diesel from your ruptured return line and they turn to mush and your motor vibrates like a box of nuts.

timebandit 01-31-2009 07:37 PM

clean the prop

lynger1 01-31-2009 08:12 PM

Hi this site wil help you
VIBRATION
Good luck

trantor12020 01-31-2009 08:58 PM

run the engine with gear in neutral see if the vib is there. if not then probably you have foul prop or worn cutlass or both.

AlanBrown 01-31-2009 10:12 PM

Here's the good news. Your vibration problem can be fixed.

The bad news that there are a myriad of things that could be causing it.

As others have mentioned, the most likely causes of the problem could be something as simple as a bent or foul prop. It could be a prop out of balance. It could be caused by a bad cutlass bearing or a bent prop shaft. A worn out or bent prop strut could be the cause. Damaged or loose motor mounts could also be the problem. As you can see, there is no simple answer.

My suggestion is to start with the things you can look at easily, the motor mounts. Also, check the bolts that hold the prop shaft to the engine for play

If you are unable to find the problem that way, depending on your location, you may have to get your boat hauled. In warmer waters, you could just put you mask on and go over the side to do a visual inspection and cleaning. For example, I have to scrub the crap off my prop a couple times a year or it vibrates like hell.

Over the years, I've had noticeable vibration problems several times. The first was caused by a bent prop. The second, loose motor mounts, and the last time, a broken prop strut.

Good luck! I hope you find a cheap and easy solution.

wchevron 02-01-2009 07:10 AM

i had this same problem this past season. i thought it was the cutless or a bent shaft. when i pulled the boat this fall, i noticed a big chunk of barnacles on the prop & shaft. i'm assuming this is the cause since the vibration got worse as the summer went along.

danielgoldberg 02-01-2009 07:18 AM

Trantor has the best idea for a first step. That mot likely will tell you if it's a problem at the engine, or somewhere else.

You don't say which engine and prop you have. Just to throw it out there, what are the max RPM for your engine? Some engines are slow turning and they top out around 1900 or 2000 RPM. If yours is one of those, the answer could be as simple as you are pinning the engine at full throttle.

Another possibility could be engine alignment. I doubt that's it because you would experience symptons even at the lower RPM, but you never know.


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