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31-08-2007, 14:54
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#1
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Registered User
Join Date: Jul 2006
Location: Airlie beach (for the moment)
Boat: newport30, Blues Traveler
Posts: 141
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In gear or out when sailing?
ok we were having a chat the other day around the pub if you leave your engine in gear when sailing so as to stop the prop turning. the argument was that if left out of gear and the prop is turning it makes the gears in the box run on the back faces of the gears causing damage. of course some said this was true and some said it was rubbish. Which way do you all sail? In gear or out of gear?
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31-08-2007, 15:26
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#2
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Registered User
Join Date: Jun 2006
Posts: 726
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sailing in gear or out
it depends on the transmision you have, some are designed for it others aren't.
also if it is hydaulic as a rule unless you have a brake set up you cannot stop the shaft from turning
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31-08-2007, 16:01
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#3
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Registered User
Join Date: Jul 2004
Location: Stuart, FL & Bahamas Cruising
Boat: Lagoon 37
Posts: 880
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we have a hurth transmission and it recomends putting it in reverse to lock it from spinning
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31-08-2007, 17:08
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#4
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Moderator Emeritus
Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
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It's all about the transmission cooling. Read the transmission docs. based om the advanced studies done by the Navy they say lock the prop. The difference if there is no transmission issues is pointless to argue. You can't go that fast one way or another so long as your transmission is properly cooled. All my boats say lock in reverse with the Mickey Ears up (like you could really check).
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
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31-08-2007, 18:30
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#5
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Registered User
Join Date: Aug 2007
Posts: 5
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Having owned one boat and chartering boats for the past three years, I have made it a practice to always sail with the transmission in reverse. I figure if it doesn't need to be in reverse, it certainly want hurt (that,s an engineer's viewpoint anyway ) We owned an Oday 28 at one time and if I forgot to put the transmission in reverse, I would always know because I could actually hear and feel the transmission turning.
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31-08-2007, 18:33
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#6
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Registered User
Join Date: Apr 2006
Posts: 4,413
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MD17D with a direct drive - In reverse for sailing.
jef
sv shiva
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31-08-2007, 20:48
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#7
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Registered User
Join Date: Apr 2007
Location: Marina del Rey, California
Boat: President 43 Sportfish
Posts: 4,105
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Quote:
Originally Posted by viking69
ok we were having a chat the other day around the pub if you leave your engine in gear when sailing so as to stop the prop turning. the argument was that if left out of gear and the prop is turning it makes the gears in the box run on the back faces of the gears causing damage. of course some said this was true and some said it was rubbish. Which way do you all sail? In gear or out of gear?
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Yo Viking,
in reverse is most common, as it is possible to damage some transmissions. A spinning propeller is presumed to create significantly more drag.
best, andy
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
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31-08-2007, 21:44
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#8
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Registered User
Join Date: Jul 2005
Location: new zealand
Boat: Lotus 10.6
Posts: 1,270
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Our Volvo manual says in reverse. Saildrive.
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01-09-2007, 02:54
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#9
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cruiser
Join Date: Aug 2005
Location: No longer post here
Boat: Catalac Catamaran
Posts: 2,462
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I think if you do a search on here for this issue, you'll find this has been dicussed time and time again. It's a question for which there is no correct answer.
Transmissions which have an independent oil supply may be sailed in neutral. Those which are lubricated from the engine sump, must be locked, usually in reverse. The difference in speed is seldom more than 1/2 knot with one 2 bladed prop in the water.
On my boat it's a a 1 knot difference with two, 2 bladed props.
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01-09-2007, 13:03
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#10
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Registered User
Join Date: Jul 2006
Location: Airlie beach (for the moment)
Boat: newport30, Blues Traveler
Posts: 141
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ok thanks all. it would appear that most run with it locked in gear.
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01-09-2007, 16:13
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#11
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Registered User
Join Date: Aug 2004
Location: Hudson, Florida
Boat: Angela M. Bayfield 32c
Posts: 63
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This is from Yanmarhelp.com......
The gear lever should never be put into ahead to stop the shaft turning. Yanmar recommend that the gear lever is left in neutral as this will not damage the gearbox. If left in astern the clutch cone may jam and will only release once the engine is started. This means you have to start the engine in astern gear. Unfortunately some boats (particually American boats - U.S. Coastguard reg) are fitted with "start in gear protection" this prevents the engine from starting if it is in gear, this would leave you unable to start the engine.
Ideally a shaft brake should be used to prevent the shaft from turning
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01-09-2007, 17:35
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#12
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cruiser
Join Date: Aug 2005
Location: No longer post here
Boat: Catalac Catamaran
Posts: 2,462
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Right... I have twin Yanmars and my manuals say the same thing.
Shaft breaks would save a little wear and tear on the cutlass bearing, but I enjoy sailing fast so my transmissions are both in neutral while sailing. By the way, if you do have Yanmars, it's also the safest per the manual.
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01-09-2007, 18:39
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#13
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Registered User
Join Date: Jan 2005
Posts: 47
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Rick,
you said you enjoy sailing fast so you leave your transmissions in neutral. If you do an internet search you'll actually find many sources to state that a fixed prop has less drag than a rotating prop. Surprising, but through all my internet research this seems to be the concensus.
Our Yanmar 3QM30F has a Kanzaki KH18 gear box which has a bath type cooling system. Yanmar says it's okay to let it free spin but we use a shaft lock made by Shaftloc, works pretty good.
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01-09-2007, 21:29
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#14
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Registered User
Join Date: Aug 2003
Boat: Dragonfly 1000 trimaran
Posts: 7,159
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I'm a big fan of folding or feathering props. Had a 3 blade maxprop on my last boat and my current boat has a Gori 2 blade. It's ok but I'm looking...
Steve B.
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02-09-2007, 01:48
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#15
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Senior Cruiser
Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
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Quote:
If you do an internet search you'll actually find many sources to state that a fixed prop has less drag than a rotating prop. Surprising, but through all my internet research this seems to be the concensus
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This is because a Propellor is a form of a "Rotary Wing". Each blade is a wing and once water flows over it's surface correctly, it creates "lift" just like any wing. If a prop is allowed to free wheel in the water, then it will act in the same way a Helicopter uses Auto rotate to stop it from going into the ground when the engine fails. The drag on the boat is created as the speed of propellor rotation increases. As it increases, more resistance to the rotation is applied by friction from the gearbox. So the propellor becomes drag to the boat, just like the helicopter blade. It is less noticable at slow speeds and greatly increases as speed increases.
If the propellor is locked, then water flows over the blade in the wrong way and the blade "stalls". This has a reverse affect. At low speed, the drag of the stalled propellor is large. At a higher speed, the drag is less noticable to the increased force from the wind.
I won't go into the issue of in/out of gear. As Rick505 said, there has been a lot discussed int he past and a search will reveal much information.
__________________
Wheels
For God so loved the world..........He didn't send a committee.
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