Last sailing season I encountered a problem when I was pulling into my slip when creeping in at about 700 PRMs. At that slow speed the engine whould make a knocking noise and the only way to stop if from happening was to either increase or decrease the RPMs. That causes a problem when I am fighting current while attempting to dock. I did have the engine mechanic out and we were able to reproduce the noise and found that it wasn't the engine that was a problem but the propeller shaft would shake at the 700 - rpms. The mechanic said that he thought it was the cutlass bearing and I should replace it once the boat is out of the water. I was also told that to determine if the cutlass bearing was gone was to try to move the shaft up or down and side to side. If you feel movement than it should be replaced. Well... I couldn't feel any movement. Has anyone else experienced this problem and what would be the best solution
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Pete
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Paul Akers
Mounts/alignment
I once had a "rattle" at low rpm's, also. I had the yard look at it ad they adjusted the motor mounts and aligned the shaft - noise has been gone since.
I once had a "rattle" at low rpm's, also. I had the yard look at it ad they adjusted the motor mounts and aligned the shaft - noise has been gone since.
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Mark Smith
Might just be this simple...
I had the same kind of knocking untill I tightend my stuffing box. Stopped in my case!
I had the same kind of knocking untill I tightend my stuffing box. Stopped in my case!
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Mickey Goodman
Rattle Noise
I had the shaft aligned to the transmission, checked the strut, adjusted the stuffing box and still had the problem. I haven't checked if the shaft is "true" while it is out of the water. Thanks, for the input.
I had the shaft aligned to the transmission, checked the strut, adjusted the stuffing box and still had the problem. I haven't checked if the shaft is "true" while it is out of the water. Thanks, for the input.
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Walt
What kind of engine...
...do you have in your 37? The Yanmar 3QM30 in my 37c (a three cylinder engine) is always pretty rough, but more so at certain rpm settings. I know for sure my engine doesn't like low rpms, especially when cold. I don't think any diesel does. Possible causes? rough engine, loose engine components, bent shaft, misaligned shaft, worn cutless bearing, broken cutless bolts (happened to me), deteriorated engine mounts, engine mounts not firmly fastened to the bed (also happened to me -- bolts pulled loose). After you check things out visually, the best thing might be to have someone take a look and listen while you try to make the sound occur. Don't you love these things?
...do you have in your 37? The Yanmar 3QM30 in my 37c (a three cylinder engine) is always pretty rough, but more so at certain rpm settings. I know for sure my engine doesn't like low rpms, especially when cold. I don't think any diesel does. Possible causes? rough engine, loose engine components, bent shaft, misaligned shaft, worn cutless bearing, broken cutless bolts (happened to me), deteriorated engine mounts, engine mounts not firmly fastened to the bed (also happened to me -- bolts pulled loose). After you check things out visually, the best thing might be to have someone take a look and listen while you try to make the sound occur. Don't you love these things?
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Pete
shaft knock
Mickey- another thought occured to me after reading the other post, I don't know what engine you have but check the mfg. spec for idle speed. 700 rpm's sounds like it might just be a little slow (I know the 3gm30 should idle at 800 to 900) It could be so slow that the vibration is causing the shaft knock at that speed. Just another thougth after reading you had done the other work. Sometimes you get lucky and it is the simple things! ! !
Mickey- another thought occured to me after reading the other post, I don't know what engine you have but check the mfg. spec for idle speed. 700 rpm's sounds like it might just be a little slow (I know the 3gm30 should idle at 800 to 900) It could be so slow that the vibration is causing the shaft knock at that speed. Just another thougth after reading you had done the other work. Sometimes you get lucky and it is the simple things! ! !
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Joe
Muffler
My muffler was rattling under the aft bunk (Hunter 29.5 with 2GM20). I used 1/8” rubber to insulate it. No more noise! Joe G.
My muffler was rattling under the aft bunk (Hunter 29.5 with 2GM20). I used 1/8” rubber to insulate it. No more noise! Joe G.
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Gene B. s/v Paradigm
Muffler info
Joe, I'm interested in what you did with your muffler. Could you provide more information, please? How did you get to it, what did you use, how did you mount, etc? Thanks.
Joe, I'm interested in what you did with your muffler. Could you provide more information, please? How did you get to it, what did you use, how did you mount, etc? Thanks.
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Mickey Goodman
My Engine is a 3HM35F
I was able to reproduce the rattle with the boat tie to the dock and saw the shaft rattle. If I came into my slip at 800 RPMs I would be going to fast and would end up by running into the dock.
I was able to reproduce the rattle with the boat tie to the dock and saw the shaft rattle. If I came into my slip at 800 RPMs I would be going to fast and would end up by running into the dock.
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Pete
Mickey
Just for fun check what the mfg. engine idle spec is. As far as 800 being to fast alot of people are in neutral when coming into the dock and I have seen and even had to use reverse to slow myself down once or twice. Just because you have aroused my curisoty please let us know (when you fix it) what was causing you shft to knock. Good Luck !
Just for fun check what the mfg. engine idle spec is. As far as 800 being to fast alot of people are in neutral when coming into the dock and I have seen and even had to use reverse to slow myself down once or twice. Just because you have aroused my curisoty please let us know (when you fix it) what was causing you shft to knock. Good Luck !
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