I recently read an article about diesel engines reaffirming that diesels do not like to be operated without a load on them, that idling for extended periods can cause glazing of the cylinder walls, leading to reduced compression and all sorts of other less good things.
This article pointed out that motor sailing can frequently create less load on the engine than would exist if the boat were just motoring as the wind pushes on the sail(s) and the boat accelerates. Depending on the conditions this could, over time, lead to glazing on the cylinder walls. The author recommended to run the engine “hard” under full load [ie. not motor sailing] for at least 30 minutes at the end of a motor sailing trip to help reduce / eliminate any potential glazing that may have accumulated. Seemed a reasonable preventative action one could take. Did a 6 hour delivery motor sailing this spring in a quite variable northerly. During the gusts was sailing considerably faster than the motoring speed and could hear / feel the prop “un-load” and occasionally did get some of the vibration Dave mentioned. Have a Flex o Fold geared 2 blade prop which probably started to partially close as the boat accelerated. Brian From: CnC-List <cnc-list-boun...@cnc-list.com> On Behalf Of David Knecht via CnC-List Sent: Wednesday, July 31, 2019 11:50 AM To: CnC CnC discussion list <cnc-list@cnc-list.com> Cc: David Knecht <davidakne...@gmail.com> Subject: Re: Stus-List Motorsailing Thanks Andy- I had not thought of that specific issue. In fact, I have a Maxprop so that would fit your explanation. Dave On Jul 31, 2019, at 11:00 AM, Andrew Burton via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: 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://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 <mailto:cnc-list@cnc-list.com> > wrote: Motor sailing as you described should not present any issues. From: David Knecht via CnC-List <mailto:cnc-list@cnc-list.com> Sent: Wednesday, July 31, 2019 9:37 AM To: CnC CnC discussion list <mailto:CnC-List@cnc-list.com> Cc: David Knecht <mailto:davidakne...@gmail.com> 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 _______________________________________________ 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 Dr. David Knecht Professor of Molecular and Cell Biology University of Connecticut 91 N. Eagleville Rd. Storrs, CT 06269-3125
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