My Oceanis 393 (Yanmar 4JH3E 56 HP) suffers from excessive engine vibration when revs go up between 1000-1700 rpm, whereas I do not experience any vibration when I reverse or when the boat has acquired speed, I put the lever in neutral and I increase then the revs. I have changed the engine mounts with brand new original ones from Yanmar, I believe that the engine-shaft are perfectly aligned, I have changed the cutlass bearing which was completely worn out and I took the propeller to a local specialist, who (without sophisticated equipment) told me that he cannot see aything wrong. Despite all these, the vibration is still there and I am desperately looking for suggestions! I must point out that I bought the boat secondhand 12 monthsw ago, it had the problem from the very beginning and very stupidly, after testing the boat with my mechanic, I accepted his view that this must be a simple misallignment proplem which can be fixed. Questions: 1. Can a balanced and not bent propeller cause such a vibration in a yacht like this? 2. Does it make sense to take out the propeller and run the engine in gear to see whether the shaft vibrates without the propeller?
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Shaft alignment
I'm surprised the cutlass bearing was totally worn out. The boat isn't that old to have that occur unless there's a problem with the shaft alignment or balance. I'd redo the shaft alignment. If you still get the same vibration try taking it slightly out of alignment. If doing either changes the RPMs at which you experience the vibration then you have a good idea you're on the proper path. When you do the check/adjustment make sure the shaft doesn't sag from it's own weight. If it does you wont get the adjustment correct. You may have to place something under it to support it while you measure the gap.
I'm surprised the cutlass bearing was totally worn out. The boat isn't that old to have that occur unless there's a problem with the shaft alignment or balance. I'd redo the shaft alignment. If you still get the same vibration try taking it slightly out of alignment. If doing either changes the RPMs at which you experience the vibration then you have a good idea you're on the proper path. When you do the check/adjustment make sure the shaft doesn't sag from it's own weight. If it does you wont get the adjustment correct. You may have to place something under it to support it while you measure the gap.
Vibration on Oceanis 393
Thank you Mike for your interest. Do you really think that a 30mm shaft of such a small length can bend because of his own weight? Anyway, I will try what you suggested and I will let you know. Many thanks
Thank you Mike for your interest. Do you really think that a 30mm shaft of such a small length can bend because of his own weight? Anyway, I will try what you suggested and I will let you know. Many thanks
Good to know
Mac, that's interesting and good to know. I know leaving an air bubble in it can cause it to drip and wear the bearing prematurely but never heard that it could cause vibration. I'm getting a short haul Thurs AM, I'll keep that in mind and make sure I burp it properly after we splash. Mike
Mac, that's interesting and good to know. I know leaving an air bubble in it can cause it to drip and wear the bearing prematurely but never heard that it could cause vibration. I'm getting a short haul Thurs AM, I'll keep that in mind and make sure I burp it properly after we splash. Mike
I'd consider it.
Dimitris, if you used a different prop and didn't feel any vibration it would certainly lead you to believe your prop has a problem. Unless someone has better information I would certainly consider finding a different shop to check the prop. If there aren't any then I would move forward with buying a new prop. Good luck. Mike
Dimitris, if you used a different prop and didn't feel any vibration it would certainly lead you to believe your prop has a problem. Unless someone has better information I would certainly consider finding a different shop to check the prop. If there aren't any then I would move forward with buying a new prop. Good luck. Mike
Vibration on Oceanis 393
Dear Mike, I agree with you and that's exactly what I am going to do. I feel most obliged and if you ever decide to come towards our territory please do not hesitate to contact me. degiannis@yahoo.com Take care Dimitris
Dear Mike, I agree with you and that's exactly what I am going to do. I feel most obliged and if you ever decide to come towards our territory please do not hesitate to contact me. degiannis@yahoo.com Take care Dimitris
Clean the shaft
I changed props this spring and made the mistake of not cleaning the shaft - take some emery paper - 200 grit or higher and really spend some time polishing the shaft where the prop slides on (and the key) - the old "marks" where the prop was should be copmpletely removed - it's amazing what vibration can occur with the smallest amount of grit trapped in the wrong place
I changed props this spring and made the mistake of not cleaning the shaft - take some emery paper - 200 grit or higher and really spend some time polishing the shaft where the prop slides on (and the key) - the old "marks" where the prop was should be copmpletely removed - it's amazing what vibration can occur with the smallest amount of grit trapped in the wrong place
New Prop
There has been plenty of talk in the different sailboatowners.com forums about different props. So when you get to the point of buying a new one, check out some of the historical threads on the topic. Certainly we are happy with our Flexofold, and I have heard good things about Max Prop. Good luck, it sounds like you are getting this figured out.
There has been plenty of talk in the different sailboatowners.com forums about different props. So when you get to the point of buying a new one, check out some of the historical threads on the topic. Certainly we are happy with our Flexofold, and I have heard good things about Max Prop. Good luck, it sounds like you are getting this figured out.
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