Hello,
Over the winter I had the boatyard change my mounts to the vetus k50's, change to a stainless shaft, change the stuffing box and change the cutless bearing.
Currently, in neutral the engine sounds GREAT at all rpm's. In forward, above 1450 rpm's the engine has a harmonic/vibration that will not go away as I raise the rpm's to a max of 2600 rpm's. Below 1400 rpm's the engine sounds and feels GREAT also.
When I put my hand on the stuffing box above 1450 rpm's I feel the same vibration/harmonic that I hear in the cockpit while engining.
Any thoughts/suggestions?
I wrote the above question for help and did not show up as a registered user??? :confused:
Ron: The stuffing box was original and the boatyard told me it should be changed. The shaft is new and stainless steel.
The boatyard seems to do good work, but with this kind of job it do not know. Is it possible the vibration I feel in the stuffing box is coming from the hull and going to the shaft/stuffing box?
Thanks for the input, when I call the boatyard I will be able to give them more information.
:)David
I agree with Ron, but don't forget to check the engine coupling/ shaft alignment. I just switched mounts this past winter and noticed a shake before I had the alignment right on.
Jeff, The engine coupling/shaft was aligned before the boat was put in the water and adjusted once it was in for over 24 hours. Is there a chance that the vibration is going from the hull to the shaft at the higher RPMs?
Thanks, David
David,
We can't tell you what is wrong. If everything is fine in neutral but not when in gear then it probably has something to do with the shaft turning or the engine being under load. You could have a problem with the prop., the shaft, the alignment or maybe even the lag bolts or nuts for the mounts not being tight. Something's not right and you'll just have to go through it all step by step. With my new mounts and the improved shaft centering and alignment there is no vibration at any time. Good luck!
Could you have a loose shaft zinc?
I changed the position of mine this
year and installed it closer to the
strut, and noticed less vibration.
Just a thought
Jan & Liz Rupinski
s/v La Vie Dansante
C34mkII #1311
r/v Southwind 35S "Moose"
Cape May, NJ
I did the same thing myself this winter, except that I re-used the bronze shaft. I pulled and replaced the shaft past the rudder, and due to the stress and bending felt very uncomfortable doing it. However, the result was a quieter installation throughout the rpm range, so I presume no harm was done. And I know many other C34 owners have done it this way, but I wonder if your yard did the same and whether it could have caused any lasting effect? The fact that it is quiet at some rpm, but not at others suggests to my inexperienced mind that there is something out of balance rather than mis-aligned. In that case could the prop have been damaged during removal. As suggested above, I put my zinc close (about 2 inches I think)to the strut, and BTW, the prop should only have 1/2 inch or so between the hub and the cutless bearing. (On the other hand presumably these two are not too close - the shaft moves slightly forwards or backwards depending on transmission selection - this unlikely possibility would be ruled out if the vibration is there in both directions.)
Maybe you could get the yard to listen and comment. They ought to take some responsibility, even if it is no more than an opinion.
Good luck.
John, Thanks for info...I moved my boat to Stamford CT, from Bridgeport and the boatyard has not returned my two calls. I will keep at it.
Thanks,
David
David,
Uncouple your shaft flange from the transmission by removing the four bolts. Slide the shaft and flange back about an inch. Move the shaft to its full verticle (up and down) travel. Next move the shaft to its full horizontial (left and right) travel. These distances should be about a half inch or so. Once you have the approximate center of the verticle and horizontial movement, put a block of wood or whatever under the shaft to not allow it to return to its gravity position. Now move the engine mounts to match the flange coupling. Once you have the engine so the flange slides into the transmission easily use the feeler gauge to refine the allignment to .oo3. My yard always alligned in the gravity position and I always had a harmonic vibration. Since I have followed this method on my own, bliss. Good luck.
Denny #142 Turning Point
Thanks Denny,
I am pretty handy, but I think this is over my head. The engine was aligned twice. I do not want to make a bigger mess of this by doing it myself for the first time. Is there a way to confirm that the harmonics is coming from the engine/shaft/prop/etc? I am confused...I did feel the harmonic on the stuffing box, but I just want to be sure...Some people tell me it could be going from the hull to the shaft??? :confused:
Thanks for the insight and any new ideas,
David
Howdy,
Looks like you've got some pretty good advice. I don't think you can rule out missalignment of the prop shaft because you can feel the vibration at the stuffing box, as any vibration from the prop shaft would transmit thru the stuffing box into the rest of the hull. By just backing out the coupling bolts a bit and using that .003 feeler guage already mentioned, you could check the boat yards work without too much effort.
Vibration being transmitted from the hull to the shaft? What would be the source of the vibration? The only source I can think of would be the engine, in which case you should be able to see it and feel it through the hull. And transfer of vibration from the hull to the shaft would require either shaft/hull contact, or VERY close proximity, meaning that your shaft isn't centered in the log.
Denny describes what you need to do. I'd bet you're capable of doing it. I'd also bet that you care more about how well it gets done than the yard. There have been numerous stories re: vibration (and other maladies) where owners have paid yards lots of bucks over several YEARS to resolve the problem, to no avail. When the owners did their own research (like you're doing) and took their own action, they were able to isolate and fix the problem.
Centering the shaft and aligning the shaft/engine is pretty basic. I don't see any way you could cause any permanent damage by trying it - the worst that could happen is that you decide it's not worth your trouble (after banging your head a few times on the aft cabin ceiling), so you call the yard back in to finish it.
Good luck, let us know how this ends up.
I've read this thread twice now and...
has the prop itself been checked for
fouling? If I remember correctly, a decent-
sized wrap of seaweed would cause approximately
the same symptom set, n'est-ce pas?
Rumours of my Death Persist
David
All I can share with you is my experience on my boat, but I threw a bunch of money at a new SS shaft, balanced the prop, new shaft bearing, drivesaver which made it worse. Ultimately I ditched the drivesaver, got new engine mounts which a yard helped install on half inch starboard because the new mounts were a little shorter. The yard had a small portable jack for lifting the engine. I confess a yard in FL showed me the alignment technique. I have since pulled the engine to have a rear main seal repaired and reinstalled it myself using the technique I described for alignment. My engine runs like a sewing machine now and before, the tapping noise and harmonic vibration was so loud I had to wear foam ear plugs to drive. We have lived aboard for 2 yrs now and put 2000 hrs on the engine.
Good luck,
Denny
Denny
Thanks to everybody,
I spoke to the machanic today. He thinks the zinc could be loose. Before I bring the boat on the 4 hour trip back to Bridgeport, CT I am having a diver go under and check things out. I could be the best $25.00 I ever spent. Thank you all for the advice and insight.
David :)
Thanks Ron,
I will post what the dive guy tells me tomorrow.
David
David -- I have exactly the same problem: harmonic vibration above 1400rpm that you can feel in the stuffing box (and even stop it by holding it). I also had the alignment checked multiple times then posted here, etc... my gut is it's Denny's suggestion... this was also outlined in detail in one of the old tech notes. ("Shaft Align Revisited"; 1989 no 4: http://www.c34.org/mainsheet/pdf/1989_no4.pdf (http://www.c34.org/mainsheet/pdf/1989_no4.pdf))
I haven't tried it yet... In San Francisco, you really don't motor much, so getting out of the harbor is fine at low rpm's.
Let me know what you find!
thx
-fb
I had the diver go under the boat, and in his words there are "no smoking guns." He said everything is in place. I will go over the Tech Notes with the machanic for aligment of this boat. Unfortionatly he can not see the boat till after Memorial Day. I will use her at low RPMs.
Thanks again and I will keep you up to date.
David
Thanks Frank, for your reminding me about the Post back in 1989. That's what's so great about this site. It's easy to search a subject. Sounds like between Denny's input and the 1989 post by Herb even I might give it a try. My vibration is OK but maybe it could be better?
Frank, lets get together on this since we are in the same harbor
Dave, sounds good. I've seen Wind Dragon around. I'm in B-3 and will start doing the Fri night races as soon as my boom issue gets sorted out.
Another Question:
After the diver gave me the all clear I decided to check the engine in forward at the dock to see if anything released from the shaft / prop. I brought the engine up to 2600 rpms with the boat secured at the dock and did not hear the metal harmonic sound. I did hear/feel a rolling vibration on the wheel. I do not know what is a normal feel of the engine :),
David
Update:
I finally got my boat back to the yard. They thought the engine was not aligned and said they would fix it. After a new alignment they were still not happy, so they are hauling the boat today or tomorrow to check into some other things.
Thanks to everybody who gave me advise and insight. Even though I am not doing the work myself, I feel I was able to communicate better with the machanic.
Thanks... David :)
Another Update:
After the boat was hauled the cutless was checked. The machanic told me there was a problem with the STRINGERS and this is causing the shaft to rub against the hull. He said this is sometimes a problem with production boats.
Can somebody explain to me what this means....if anything??? :)
Thank you,
David
Having taken an engine in and out of a C34 over 4 times I am very familure with Stringers,Shaft Tubes, Shafts, Engine Mounts, and Alignment......To your question"What are Stringers"? The stringers are what the engine and its mounts sit on. I find it very hard to believe that this is the problem! The only way that the stringers could be an issue is that somehow they were installed in the wrong location at the factory, thus not allowing enough room to allow all four engine mounts to sit properly on them. I just realigned my engine because I replaced the engine mounts and although I had to redrill new holes for the lag bolts there was all kinds of room to accomidate the alignment. I would really question your yard hard on this. I find it hard to beleive the stringers have a problem.
Having said that you mentioned that the yard said that your shaft was hitting the hull. I did have a problem with my C34 when it was new where by the log shaft tube was not installed at the factory correctly. The old tube had to be drilled out and a new one reinstalled due to not being able to align the engine the way it needed to be without having the shaft rub against the log tube. I had the same symptoms you describe. Once this was done everything could then be aligned easily without any interference of the shaft and tube.
Again I find it strange that this problem that has just come up. In my case I always had the problem from the time it was new until it was corrected a year later. I believe I am correct in saying that in your case you have had proper alignment and no vibration. Therefore something has changed and I can tell you it is not the shaft tube and it is not the stringers. Review the previous comments again as they are sound advise on proper alignment steps.
Just my thoughts....
Kelly