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-   -   Sailing ... transmission in reverse? (http://www.sailnet.com/forums/beneteau/142538-sailing-transmission-reverse.html)

JohnB40 05-25-2014 06:38 PM

Sailing ... transmission in reverse?
 
Hi

Have a 2009 Beneteau 40 with Yanmar 4JH4AE engine. Sorry ... don't know which transmission.

Was told when bought boat in 2011 not to put it in reverse when sailing (to stop prop turning). If I put in reverse then have to almost stop boat to get into neutral.

I have now read that leaving shaft turning while sailing leads to much quicker wear so should engage reverse.

Any comment?

I will try and find transmission type but info plate on engine leaves this space empty!!

Thanks, JohnB40

Stumble 05-25-2014 08:14 PM

Re: Sailing ... transmission in reverse?
 
John,

It depends on the transmission. Some need it locked some can handle free spinning. Either way it is faster to keep the prop from spinning so neutral is generally the worst option unless your folding/feathering prop prefers it.

Maine Sail 05-25-2014 09:31 PM

Re: Sailing ... transmission in reverse?
 
Quote:

Originally Posted by Stumble (Post 1871290)
. Either way it is faster to keep the prop from spinning so neutral is generally the worst option unless your folding/feathering prop prefers it.

Completely untrue.... Old wives tales die hard...

Yanmar adamantly and strongly advises their gears be locked only with a shaft brake or allowed to free spin...

gamayun 05-26-2014 05:53 AM

Re: Sailing ... transmission in reverse?
 
The spinning prop will drive you crazy. I put it in reverse while sailing, then put the boat in irons to slow it down and get it into to neutral before I crank the engine. It slides right in if there's no pressure. I think the problem comes when trying to force it out of gear. I have a Yanmar 3GM30. Anyway, as you'll see,the advice on this seems to be all over board....

Maine Sail 05-26-2014 09:30 AM

Re: Sailing ... transmission in reverse?
 
Quote:

Originally Posted by gamayun (Post 1871874)
The spinning prop will drive you crazy. I put it in reverse while sailing, then put the boat in irons to slow it down and get it into to neutral before I crank the engine. It slides right in if there's no pressure. I think the problem comes when trying to force it out of gear. I have a Yanmar 3GM30. Anyway, as you'll see,the advice on this seems to be all over board....

The problem comes because water movement over the prop wears the cones over time and eventually causes slipping of the gear necessitating a rebuild. Yanmar had so many issues they issues an MSA on the topic to all dealers. Folks have also broken gear linkages etc..

Yanmar MSA - Gear Position While Sailing


Advisory Number: MSA08-003:

DATE February 8, 2008 Dealers and OEMs
TO: All Marine Distributors
SUBJECT: Gear in Neutral While Sailing All MODELS:

All Sailboat Engines

We continue to get questions regarding the correct gear position while sailing with the engine OFF. This advisory is issued as a reminder; Yanmar requires that if sailing with the engine OFF (not running) the transmission shifter must be in the neutral position or internal damage to the gear or sail-drive will result. This damage will not be covered by Yanmar’s Limited Warranty. Please instruct customers and dealers who deliver the sailboat to the customer, of the correct (Neutral) position for the marine gear while sailing.

If the customer desires that the propeller shaft not spin while sailing, either a folding propeller, shaft break, or other suitable device may be used. However, Yanmar accepts no responsibility for the selection, installation, or operation of such devices. Please also refer to Marine service advisory “MSA07-001_Yanmar Sail Drive Propeller Selection” for additional information.

If you have any questions regarding this advisory please contact a Customer Support representative.

Stumble 05-26-2014 04:01 PM

Re: Sailing ... transmission in reverse?
 
As I said it depends on your transmission. But allowing the prop to spin, ie neutral without a shaft break, is slow.

fmueller 05-26-2014 05:03 PM

Re: Sailing ... transmission in reverse?
 
This is incorrect. Their is no reason a spinning prop would create more drag than a fixed one (except folding props of course). The opposite is almost certainly true.

Sent from my XT1060 using Tapatalk

Maine Sail 05-26-2014 05:06 PM

Re: Sailing ... transmission in reverse?
 
Quote:

Originally Posted by Stumble (Post 1872962)
As I said it depends on your transmission. But allowing the prop to spin, ie neutral without a shaft break, is slow.

Sorry you have it backwards. A freewheeling sailboat prop has LESS DRAG not more..

gamayun 05-26-2014 09:55 PM

Re: Sailing ... transmission in reverse?
 
See study results (link below) from 2008, which stated the following in its findings, though I still contend that a rotating propeller will Drive_You_Crazy: "The experimental results confirm that a locked propeller produces greater drag than does a freewheeling screw (up to 100% more drag was observed, this being at higher speeds). Furthermore, for the freewheeling case, the magnitude of the hydrodynamic resistance is significantly affected by the amount of frictional torque on the shaft, low torque being accompanied by low drag."

Sailboat propeller drag

Alex W 05-27-2014 01:10 AM

Re: Sailing ... transmission in reverse?
 
Note that Yanmar does allow you to shift into reverse while sailing if you have a folding or feathering prop. That's good since some props won't fold or feather without locking the shaft. Even so I usually put it into reverse for a few seconds, then back into neutral when the prop feathers.

When I had a non-feathering prop I did confirm on my own boat that freewheeling was faster than locking the prop shaft.

Putting on a feathering prop last winter was the best performance upgrade that I've made to the boat.


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