"Grind and polish"!? Have you ever felt how freely and noiselessly the shaft rotates by hand in N when the packing gland nut is backed off a bit? I'm pretty sure that if N was detrimental in any way the Hurth instructions would not include this option. In the 12,000 nm's on our cat of sailing with fixed 2-blade props in N - before the MaxProps - no transmission problems. Why maximize your prop drag by stopping free rotation?
In or out of gear
- Thread starter brad minda
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but the questioner has an M25, not anM18 or anything else. nobody seems to think that sailing with am M25 is wrong, so what's the problem?
This is for Yanmars with sail drives only, as in my 37' catamaran above. But the principle should be the same for either cone clutch (Hurth uses this, I believe) or dog clutch: trying to stop the rotational force of a fixed prop with the clutch mechanism of your transmission obviously stresses it, and may prevent it from shifting or other wise damaging it.
Consider the damage your auto drive train may sustain if, with manual tranny in reverse, coasting forward down a hill and letting the clutch out to stop the car. Or, with your 3-blade fixed prop, rotation stopped by R gear, surfing down a west coast roller at 10 K. Huge internal stresses...
Get a folder or featherer, then stop it in reverse. Otherwise, spare your driveline with N. under way.
Pete
pete, i think you have it backwards. leaving the transmission in neutral allows the prop to spin the shaft when you're sailing. leaving it in reverse locks the prop - no wear no tear.
I think not! If you agree that there's a rotational torque on the prop shaft stopped in Rev. with a fixed prop, that increases proportionally with sailing speed, what part of the transmission takes this stress? The clutch dog or cone assembly, of course, as explained in the Yanmar bulletin link in Weinie's post above, and it can cause failures. Sure, a free-wheeling prop will cause some Cutlass bearing and shaft log packing wear, but these are long-lived elements easily dealt with every few years at haulout time.
Pete
Morty,
You would be well served to actually read the thread and what has actually been posted in terms of official documentation from both Hurth / ZF and Yanmar/Kanzaki.
Yanmar marine specifically requires neutral for both their cone clutches and dog plate clutched reversing gears if a fixed prop is used. If you insist on locking a Yanmar/Kanzaki gear they require the use of a shaft locking device NOT by using reverse. Less damage occurs with a Yanmar/Kanzaki when you leave it in neutral than occurs from locking it in reverse and this is why they have issued both Marine Service Advisories and Technical Bulletins on the matter.
TECHNICAL BULLETIN : Yanmar Sailboat Engine Control Lever Position During Sailing With Engine Stopped.
Carl Hurth / ZF Marine says neutral OR locked in reverse (or locked in direction opposite of travel)
This too:
Before calling other posters out as having it "backwards" you may want to read the multiple instances of official documentation that has been presented.
I have a beta 25 and if it's in neutral the shaft will spin. But if the transmission is left in forward or reverse there is no motion of the shaft. There's just not enough pressure for the engine to turn over when it is left in gear, hence there is no spinning of the shaft in either forward or reverse. So I don't see what the difference is in my application of forward or reverse question. Either/or works for me.
In defense of Mort, Hurth instructions say reverse or neutral. Locked would mean less wear. In defense of Piney, locked would put more strain on the clutch. As Maine Sail advices, it makes sense to follow the manufacturer instructions.
Those of us with Hurth transmissions have the option of sailing in neutral or reverse. I usually sail in neutral for safety reasons so the engine is not accidentally started in gear. Once we get over six knots, the speed on the shaft makes it so noisy I lock it in reverse. The running gear then quiets down and stops complaining so we can enjoy the sail.
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this thread has probably long since past the point of bordedom so to put an end please list all the reasons not to sail in reverse.
The reasons, for various transmissions, have already been posted multiple times.
- Increased Drag & Slower sailing speeds, when locked in reverse with a fixed blade prop
- Physical damage to Yanmar/Kanzaki gears are a direct result of locking in reverse.
- Additional load on the starter when you forget to move back to neutral before starting the engine.
I'm sorry you've become bored but it has only dragged on because you stated this:
Please provide the evidence or documentation out there to support the claim that leaving a Hurth/ZF in neutral will cause the plates to "grind & polish each other". The actual gear manufacturer states the exact opposite.
Like the Hurth/ZF, Twin-Disc/Technodrive, if you have a TMC-40 or TMC-60 on your Beta 25, suggest that leaving it in forward is bad for the gear and can cause damage. They prefer neutral or reverse but not forward. Stanly can also support this.. It seems like you prefer to lock it so choose reverse and you'll be safe with a Technodrive.
Before we changed to feathering 3-blade MaxProps on our 37' catamaran, the saildrive Yanmar 20's had 2-blade fixed props, and we always sailed in neutral because of the higher sailing speeds and drag. But the 90deg. bevel gears of the Z-drives would raise a banshee howl as speeds increased, making the two queen-sized berths over the engines uninhabitable as we ran before an un-forcast gale down the northern CA coast under Solent jib alone, hitting 16-18 knots down the big ones. No question in my mind that the force generated with Rev stopped props would have turned the engines over backwards.In defense of Mort, Hurth instructions say reverse or neutral. Locked would mean less wear. In defense of Piney, locked would put more strain on the clutch. As Maine Sail advices, it makes sense to follow the manufacturer instructions.
Those of us with Hurth transmissions have the option of sailing in neutral or reverse. I usually sail in neutral for safety reasons so the engine is not accidentally started in gear. Once we get over six knots, the speed on the shaft makes it so noisy I lock it in reverse. The running gear then quiets down and stops complaining so we can enjoy the sail.
We did experience this once in rough Carib. waters with the maxprops feathered in Rev, close-reaching at 8-10 kts. when one of the props was thrown un-feathered, and began turning the engine over, presumably backwards - I first thought we had run over something. Heading up and slowing down stopped it, and I went to N, then R to re-feather. No apparent engine damage from it, but a couple of scary minutes.
I'm thinking that Rev. is preferred to stop the prop because the passive torque stress on the clutch components under sail is in the same direction as the active torque in Fwd under power.
Pete
enough, i apologize. the first questioner asked about an M25 and i had asked hurst, when they were still around, about an M25. if they, or i, or both are wrong i'm sorry. your boat, your tranny, enjoy.