I think you are on the right track with your diagnosis. I’ve found that with a feathering prop if you start sailing faster than the prop is driving the boat you can get a vibration. I assume this is because the prop partly feathers.
Andy Andrew Burton 139 Tuckerman Ave Middletown, RI USA 02842 www.burtonsailing.com http://sites.google.com/site/andrewburtonyachtservices/ +401 965-5260 > On Jul 31, 2019, at 10:05, Matthew L. Wolford via CnC-List > <cnc-list@cnc-list.com> wrote: > > Motor sailing as you described should not present any issues. > > From: David Knecht via CnC-List > Sent: Wednesday, July 31, 2019 9:37 AM > To: CnC CnC discussion list > Cc: David Knecht > Subject: Stus-List Motorsailing > > We just got back from a long cruise (long for us- 5 days) where the wind > tended to be against us every day. We ended up motor sailing some of the > time fairly close hauled with winds varying 5-10 knots. We were pressed > for time and wanted to keep our speed up and direction to our destination so > that ended up with some pinched sailing a bit too close to the wind, but > better than either motor alone or sail alone. Periodically, (especially as > the wind increased) the engine/hull would start intensly vibrating and if I > adjusted engine rpm, I could usually get it to stop. I am presuming that I > was getting resonances in the engine/prop due to the sails and prop trying to > drive the boat simultaneously and not always in sync. Obviously strong > vibrations are not a good thing, but my question is whether motorsailing like > this is a bad idea altogether due strain on transmission/engine. Thanks- Dave > > S/V Aries > 1990 C&C 34+ > New London, CT > > <pastedGraphic.tiff> > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each and > every one is greatly appreciated. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each and > every one is greatly appreciated. If you want to support the list - use > PayPal to send contribution -- https://www.paypal.me/stumurray >
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