I'm replacing my motor mounts this year to deal with excessive vibration and noise. Could that be your problem? Andy C&C 40 Peregrine
On Thu, Jan 9, 2014 at 12:46 PM, William Hall <wh...@alum.mit.edu> wrote: > Dear List, > > I've been troubleshooting quite a vibration problem since I got my boat a > year and a half ago. I had hoped it all just needed an alignment, but that > does not appear to be the case. I'm hoping that if I present the situation > someone on the list may be able to point me in the direction of a fix! > > The boat is Starfire, my 1985 C&C 37. It has a Yanmar 3HMF. I believe it's > the original engine, but was overhauled a few years ago. The previous owner > said it was overhauled because it was no longer producing enough power. > > The engine drives a 2-blade max prop. There's a line cutter on the shaft. > There's an R&D marine elastomeric coupling between the end of the prop > shaft and the engine drive shaft. > > When I bought the boat, we noted a lot of vibration when in gear above > about 1800 rpm. The surveyor thought it needed alignment and noted as well > that the max prop had more play in it than it was supposed to. I hauled it > that first winter, had the max prop sent back to max prop for overhaul, had > new cutlass bearing installed, and when it all came back together in the > spring found the same vibration as before. When running in forward, the > prop shaft deflects significantly at higher RPM's (maybe 1" of wobble at > the worst point along the drive shaft), and things shake in a way that > can't be good. In neutral, as well as reverse, it runs smooth as silk > right up into high rpms. > > I've since had a few engine / drive people look at it and try to figure it > out. The shaft appears to be true. The alignment appears to be right on, as > measured by two different mechanics. The elastomeric coupling was a bit > worn, so we put a new one in. The engine mounts are substantial and seem > good. The engine people think there's something wrong with the prop that > the overhaul didn't fix. > > What does the list say? Is it the prop? Could there be something wrong in > the transmission, say a thrust bearing or something? In flat calm I can > get almost 5 knots without too much worry of breaking things, but into a > sea or wind I'd really like to have the option to use more power. What > would you try? > > Thanks in advance for the thoughts. > > Regards, > Bill > > 1985 C&C 37 - Starfire > Stamford, CT > > -- > William D. Hall, Ph.D. > 203 653 2886 (o) > 617 620 9078 (c) > wh...@alum.mit.edu > > _______________________________________________ > This List is provided by the C&C Photo Album > http://www.cncphotoalbum.com > CnC-List@cnc-list.com > > -- Andrew Burton 61 W Narragansett Ave Newport, RI USA 02840 http://sites.google.com/site/andrewburtonyachtservices/ phone +401 965 5260
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