Best way to prevent the engine block from vibrating

I have a friend who has replaced the engine with a new one. The engine has been shaking since. He has replaced the engine mounts and new brackets, but that seems not to work. Given that the engine runs, and vibrations do occur, the person is out of options. During the engine replacement the mounts and brackets were replaced and refrabricated to compensate for any difference, but still the vibration is occuring to the point of concern? Too much vibration will cause friction against other lines and connections, as most sailors are aware of.  Any suggestion?

It does not happen when the vessal is in nuetral. Reverse is worse.

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The props are cleaned every month, as the hull is as well. This should not be the case. Non of the cleaners have stated they've seen anything odd. We get to deal with it this Friday. I will keep you in the loop of what we find. Maybe we aught to just get rid of the mounts and use wood as you did! LOLOL, only kidding. Those mounts were pre-fabbed for the engine, could not waste good money...O' wait, that would be part of being a boat owner! "humor"

All I know, we worked hard on her, and all was good for weeks, now this. We just want to nab the issue before it does turn into a bigger issue. It should run smoothly, in gear it does, as long as it is at or above 15 RPMs . It should run smoother then it is. If the RPM's drop below 15, the engine vibrates like hell, not always good, while in gear mind you. Neutral is fine.

it could even be the prop got bent a bit.  a diver can do a visual check on that too.  He should know how to do that.  Remember hitting anything while motoring?
That is not even an option, we have not hit anything! I have never. This is FL. anyway, you would have to be an unaware individual to "find" something to hit the prop. on given that it is all soft sand if anything. It's called a depth gauge, they are a very helpful instrument, so that is not an option. Like I stated, including the Capt. himself checking the bottom, so does the boat cleaner, bent prop is not the issue.

Well, it most likely is one of two issues then.  Alignment or a prop issue.  That is my story, and I'm sticking to it.



there you go Capt. Steve, 

you say it! :)  I just must be a glutten for this stuff, I enjoy working on sailboats, it's different from what my field is actually. I appreciate your advise and will check all situations out. I will keep you informed on the outcome.


If it runs fine in neutral then most likely its not an engine issue.  Smooth at a variety of RPM's indicates no engine problem.

If it were a fuel delivery problem it should get worse when the throttle is applied rather than get better.

Whats the idle RPM set at.  How are you determining the engines RPM.  Are you confident in the accuracy of the on board tach?  Have you confirmed the RPM with a optical tach?

Is the prop a fixed blade, folding or feathering?  Just because you haven't hit the bottom doesn't mean the prop hasn't hit something.

If the boat performed well for the first few weeks after the rebuild I would guess that something has loosend up.  Most likely at least one of the mounts has become loose.  The easiest way to confirm this is to check the alignment.

When was the last time the cutlass bearing play was checked?



s/v Veranda

We've discussed it already, it is not, or definitely NOT to be  the fuel delivery system. The idled RPM is about 1100 to 1200 RPM. On board tach. is fine, optical tach. has been used in past by machanics, all is good there! It is a feathering blade prop.

We are counting on something just being loose, if anything, we will have to tighten here and there and re-adjust as needed.

I will keep you all informed. Thank you for your time on your post. Appreciate any/all feedback!

Talk soon,



Ha!!!  it is interesting how information comes out.  I'll bet you a dime for a dollar that the prop has not opened up fully and causing an imbalance.  A barnacle in the wrong place could very well do that and prevent one blade from fully extending.  What kind of prop do you have?
Let me double check with him, I am pretty sure it's a feather. I might be thinking "on the prop. side" of someone elses boat. I know that everyone I know has either a feather or fixed propeller, no other blades. Can't be that anyway, He and the boat cleaner do all that, as in clean the bottom. My friend is emphatic about keeping the bottom and prop clean and clear of debris. Like I stated, Friday will be the day! Fun, fun, I like this stuff and I learn, very quick!. But I will get back to you on what he has on his boat for sure.

I haven't noticed any mention of make/model of engine. Gas or diesel? I'll be checking back to see what transpires on Friday, but I bet it's going to be something simple like a loose engine mount or mis-aligned shaft. As to the folding/ feathering prop, he could have picked up a stick or something that's keeping the prop from opening. I had both blades drop off due to inferior roll pin corroding away, could be just about anything. .


It is a diesel engine, Yanmar, how I know that for sure is because I had to call the Yamar dealer to check pricing on a parts. Remember, it's a new engine, still under warranty.
Well, cancelled this, 60% chance of rain. We have to much stuff to do to fight weather. 50% chance Sat. NOAA is so great to use for boating!


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