The Max-Prop may be worn and need to be rebuilt. Check for looseness in the blades when it is hauled.
I had something similar happen when motor sailing when my prop was worn. When the wind would puff and accelerate the boat taking the load off the prop, it would shudder. Eric C&C 34/36 On Thu, Jun 16, 2016 at 2:59 PM, Tom Buscaglia via CnC-List < cnc-list@cnc-list.com> wrote: > Check your motor mounts. > > Tom Buscaglia > S/V Alera > 1990 C&C 37+/40 > Vashon WA > P 206.463.9200 > > > > On Jun 16, 2016, at 10:36 AM, cnc-list-requ...@cnc-list.com wrote: > > > > Message: 1 > > Date: Thu, 16 Jun 2016 09:25:00 -0700 > > From: Andrew Means <andrew.cnc...@gmail.com> > > To: cnc-list@cnc-list.com > > Subject: Stus-List intermitent vibration/shudder in ocean swells > > Message-ID: > > <ca+egbjxftglnif02r0sisd-krjsltzug6x47emjtxkp9sfs...@mail.gmail.com> > > Content-Type: text/plain; charset="utf-8" > > > > Hey all - > > > > My friends and I are currently in Tofino, BC on day 6 of a much needed > > vacation. So far our Yanmar GM30F and 3-bladed max-prop have been > > performing brilliantly, sipping diesel and pushing the boat through the > > less-windy sections of Strait of Juan De Fuca and up and over some large > > ocean swells on our way up to Tofino. > > > > Yesterday on the way up from Ucluelet I felt a shudder/vibration as the > > boat crested a swell. It was short but pronounced. The motor didn?t > change > > RPM at all or seem under load. About 10 minutes later it happened again, > > also over a swell. This time we had to lower the RPM of the engine and > let > > it idle - when we brought it back up it was smooth again. This happened > > maybe 6 times over the course of the passage, always starting as we were > at > > the top of a swell. > > > > We?d been going through swells at the same angle under power the day > before > > with no trouble, the only difference this time was that the little wind > > there was was behind us. > > > > The only thing I can think of is that one of the blades of the max prop > is > > feathering as we go over these swells. I have no idea how one would fix > > that - or if there?s any way to do so without hauling the boat out > (hoping > > to avoid that mid-trip?) > > > > Any ideas? > > > > -- > > Andrew Means > > S.V. Safari - 1977 C&C 34 Mk I > > Seattle, WA > > _______________________________________________ > > This list is supported by the generous donations of our members. If you > like what we do, please help us pay for our costs by donating. All > Contributions are greatly appreciated! >
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