I was wondering if it is ok to let the prop spin while under sail, or keep the transmission in forward gear? Any advise would be appreciated. Thanks, John Giaccio
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Eric Lorgus
Sail Yanmar with tranny in reverse
John: There was a post about 1/2 year ago about this. Check the archives for a post by Terry Arnold, who explained that a Yanmar transmission should be in reverse while sailing, to avoid having the small gears in the transmission turn without the lubricating action of the larger gears.
John: There was a post about 1/2 year ago about this. Check the archives for a post by Terry Arnold, who explained that a Yanmar transmission should be in reverse while sailing, to avoid having the small gears in the transmission turn without the lubricating action of the larger gears.
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Bill Ihlenfeldt
prop-gear
I have researched the topic and have found that the only way to stop the prop is to put it in reverse. If you let it spin in neutral it can cause premature wear of the bearing and in forward gear, the transmission. I always shift into reverse when sailing.
I have researched the topic and have found that the only way to stop the prop is to put it in reverse. If you let it spin in neutral it can cause premature wear of the bearing and in forward gear, the transmission. I always shift into reverse when sailing.
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Tom Senator
Catalina 36MKII manual says its OK to put Trans in
neutral when Sailing. The engine is a Universal M35A. (I can't recall the exact transmission....something like HDW-100???) It might be different for the Yanmars, though in my old boat I had a 20 year old 2QM15 Yanmar and left in neutral all the time while sailing & the engine/transmission was fine....... Old Practical Sailor article from a study at MIT said that there was an improvement in sailing speed with the propellor free spinning...especially a three blade...the faster the sailing the more drag that would incur.....translated in actual increases in speed would probably bea small fraction of a knot though.
neutral when Sailing. The engine is a Universal M35A. (I can't recall the exact transmission....something like HDW-100???) It might be different for the Yanmars, though in my old boat I had a 20 year old 2QM15 Yanmar and left in neutral all the time while sailing & the engine/transmission was fine....... Old Practical Sailor article from a study at MIT said that there was an improvement in sailing speed with the propellor free spinning...especially a three blade...the faster the sailing the more drag that would incur.....translated in actual increases in speed would probably bea small fraction of a knot though.
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Peter Clancy
Helicopter Falling!
It has always been my understanding that a locked prop creates less drag than a spinning prop. The analogy is a helicopter that loses power and allows its blades to spin freely thereby reducing rate of descent. If the blades are locked, the helicopter falls like a rock and is history!
It has always been my understanding that a locked prop creates less drag than a spinning prop. The analogy is a helicopter that loses power and allows its blades to spin freely thereby reducing rate of descent. If the blades are locked, the helicopter falls like a rock and is history!
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Jim Cook
Hellicopter falling problem.
Your correlation between a boat prop and helicopter prop in clever and it certainly is true in respect to helicopters. However, it has one flaw. The blades of a helicopter are relatively long and narrow. Therefore, locked blades do not create much resistance in relation to the large volume of air passing between the blades. The blades of a boat prop are relatively wide and short, sometimes overlapping each other. These blades tend to act more like a parachute creating significant resistance as the water has to turn direction and exert force (drag) on the locked blades as it passes between them. Keep up the creative thinking, as it generates new ideas. Happy sailing...
Your correlation between a boat prop and helicopter prop in clever and it certainly is true in respect to helicopters. However, it has one flaw. The blades of a helicopter are relatively long and narrow. Therefore, locked blades do not create much resistance in relation to the large volume of air passing between the blades. The blades of a boat prop are relatively wide and short, sometimes overlapping each other. These blades tend to act more like a parachute creating significant resistance as the water has to turn direction and exert force (drag) on the locked blades as it passes between them. Keep up the creative thinking, as it generates new ideas. Happy sailing...
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Kevin L. Woody
To spin or not
Dear John: Thank you for your question. As for as drag is concerned, the faster the boat speed the more important it is to lock the shaft and propeller in place. The greater the boat speed the less likely the rotational speed of the propeller can keep up, thus creating more drag as speed increases. A greater concern then boat speed should be transmission capabilities. Some transmission makers have limits placed on the free wheeling action. Some say as little as three hours is an acceptable amount. The reasoning is that a pump and not a bath is often used to lubricate the transmission. So it is very important that if you allow the transmission to free wheel you should start your engine periodically and place the transmission into gear allowing the lubrication process to take place. Your transmission manual will inform you of the time frame. For the few of you out their which have hydraulic transmissions, the only way to stop your fixed blade units from free wheeling is to use either a shaft brake or to replace the fixed blade prop with a low drag prop. You may find that the lubrication cycle to be even more important for hydraulic transmissions then mechanical ones. Hope this helps. Sincerely, Kevin L. Woody
Dear John: Thank you for your question. As for as drag is concerned, the faster the boat speed the more important it is to lock the shaft and propeller in place. The greater the boat speed the less likely the rotational speed of the propeller can keep up, thus creating more drag as speed increases. A greater concern then boat speed should be transmission capabilities. Some transmission makers have limits placed on the free wheeling action. Some say as little as three hours is an acceptable amount. The reasoning is that a pump and not a bath is often used to lubricate the transmission. So it is very important that if you allow the transmission to free wheel you should start your engine periodically and place the transmission into gear allowing the lubrication process to take place. Your transmission manual will inform you of the time frame. For the few of you out their which have hydraulic transmissions, the only way to stop your fixed blade units from free wheeling is to use either a shaft brake or to replace the fixed blade prop with a low drag prop. You may find that the lubrication cycle to be even more important for hydraulic transmissions then mechanical ones. Hope this helps. Sincerely, Kevin L. Woody
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