Opinion is that by placing the gear in reverse (stopping the prop spin) while sailing will save on the wear of my Yanmar 3GM (Hunter 356). However, I generally cannot return the handle (gear) to neutral for the start after the sail. I have to momentarily press the starter (while still in reverse), move the handle quickly to neutral, and then perform a normal start. Questions: (1) Does placing the gear in reverse truly make a difference in protecting the life of the engine, and (2) is there any harm to starting while in gear? Thanks.
Prop Spin Under Sail
- Thread starter Bill Glass
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Good questions
I have the same problem on the H232 and H29.5 before that. It's compounded by the annoying lack of the starter ignition sometimes.
I have the same problem on the H232 and H29.5 before that. It's compounded by the annoying lack of the starter ignition sometimes.
archives
Bill, there is a lot of material in the archives but I think the concensus was to shift to reverse when sailing and either slow to about 1 knot or start in reverse before shifting to neutral. That is what I have been doing. Starting in reverse seems not to matter but immediately slows the boat. I believe that the concern is for the freewheeling prop turning the drive shaft and a portion of the transmission, unnecessarily and causing wear. Shifting from reverse to neutral may have the risk of nicking a gear due to pressure on the gears from the prop trying to rotate.
Bill, there is a lot of material in the archives but I think the concensus was to shift to reverse when sailing and either slow to about 1 knot or start in reverse before shifting to neutral. That is what I have been doing. Starting in reverse seems not to matter but immediately slows the boat. I believe that the concern is for the freewheeling prop turning the drive shaft and a portion of the transmission, unnecessarily and causing wear. Shifting from reverse to neutral may have the risk of nicking a gear due to pressure on the gears from the prop trying to rotate.
I have the same problem with my H33, and did for my Catalina 30 before. I just start the engine while in reverse, then after it has started, pull it out of gear. I recall that the manual for the hurth transmission (C30) advised that the transmission be put into reverse while sailing to lock the shaft - but should not be put into forward while sailing. I have started my engines in reverse since 1996 and have had no ill effects that I am aware of. Michael
My experience
I attended the Mack Boring (Yanmar) class last year and the instructor strongly reccomended not to start in reverse because there is a whole lot to force being suddenly put on the reverse gear. According to what I have read and now do as standard procedure is to point the boat up to the wind to slow it down to less than 1 knot and then it easily goes into neutral and can be started. Admittedly at times when things are hectic you need to move quickly.
I attended the Mack Boring (Yanmar) class last year and the instructor strongly reccomended not to start in reverse because there is a whole lot to force being suddenly put on the reverse gear. According to what I have read and now do as standard procedure is to point the boat up to the wind to slow it down to less than 1 knot and then it easily goes into neutral and can be started. Admittedly at times when things are hectic you need to move quickly.
type of transmission and number of prop blades
Bill - A cone-type transmission (like the KM series as on my 05H36's 3YM30) will suffer no harm from a free-wheeling prop. Their only rotating component is the (now uncoupled) drive shaft and its gearbox exit bearing - both of which are low enough to be well oiled unless your gearbox oil is all gone. Whether or not you should fix the prop or free wheel it depends on the number of blades. A Navy study of the issue for large multi-engine/prop vessels apparently showed a slight drag reduction/speed increase for a fixed 2-blade prop (especially when it was aligned with the keel), and a significant drag reduction for free-wheeling a 3-blade. My measurements on my own boats have been consistent with the Navy's conclusions. On my old 99H310 I found that fixing its 2-bladed prop gained me 1/4-to-1/3 kt of speed under sail. On my 05H36 I've found that free-wheeling its 3-bladed prop gains me 0.5 kts over the fixed prop. So, I've had my H36's prop turning over 3200nm - with no adverse effects on transmission or cutless bearing. If you listen closely, there is a very slight low-pitched throbbing/drumming noise from the cockpit floor as each blade passes close to the hull bottom while rotating. However, going below and touching finger tips to the transmission case shows no vibration and the case's exit bearing spins as quietly as a (well-oiled) mouse. My annual haul inspection of the cutless bearing once again shows no play at all. PS for those who wish to avoid "counting the number of teeth in the horse's mouth" as I've done, and instead of measuring on their own boat rely on theorizing about fluid drag - remember that the dynamics of incompressible fluids (like seawater) are very different from those of compressible fluids (like air) before posting the usual airplane prop-feathering analogies. Fair winds
Bill - A cone-type transmission (like the KM series as on my 05H36's 3YM30) will suffer no harm from a free-wheeling prop. Their only rotating component is the (now uncoupled) drive shaft and its gearbox exit bearing - both of which are low enough to be well oiled unless your gearbox oil is all gone. Whether or not you should fix the prop or free wheel it depends on the number of blades. A Navy study of the issue for large multi-engine/prop vessels apparently showed a slight drag reduction/speed increase for a fixed 2-blade prop (especially when it was aligned with the keel), and a significant drag reduction for free-wheeling a 3-blade. My measurements on my own boats have been consistent with the Navy's conclusions. On my old 99H310 I found that fixing its 2-bladed prop gained me 1/4-to-1/3 kt of speed under sail. On my 05H36 I've found that free-wheeling its 3-bladed prop gains me 0.5 kts over the fixed prop. So, I've had my H36's prop turning over 3200nm - with no adverse effects on transmission or cutless bearing. If you listen closely, there is a very slight low-pitched throbbing/drumming noise from the cockpit floor as each blade passes close to the hull bottom while rotating. However, going below and touching finger tips to the transmission case shows no vibration and the case's exit bearing spins as quietly as a (well-oiled) mouse. My annual haul inspection of the cutless bearing once again shows no play at all. PS for those who wish to avoid "counting the number of teeth in the horse's mouth" as I've done, and instead of measuring on their own boat rely on theorizing about fluid drag - remember that the dynamics of incompressible fluids (like seawater) are very different from those of compressible fluids (like air) before posting the usual airplane prop-feathering analogies. Fair winds
Neutral vs reverse
Well forward is right out. Neutral allows the prop, prop shaft and transmission secondary shaft to all spin and reverse causes the whole system to "jam up". The neutral option causes more ware, and there is the possibility of getting a line wrapped and you get a slight increase in speed. The reverse option cause the prop to try to rotate the engine backwards. Since this is rather difficult there is a lot of pressure on all the gears and bearings and you get a slight decrease in speed. If this is all about speed under sail then just go out and buy a sailing prop and get rid of your motoring prop. They ALL have less drag and no wear while under sail. This is how the sailing bug creeps into your life. First it is "I have to get that prop to save my transmission". Later it becomes "I have to get that carbon-fiber mast to get my weight aloft down". And after a few races (formal or informal) "I really need that carbon-carbon-mylar mainsail to keep my flow from separating". ;-)
Well forward is right out. Neutral allows the prop, prop shaft and transmission secondary shaft to all spin and reverse causes the whole system to "jam up". The neutral option causes more ware, and there is the possibility of getting a line wrapped and you get a slight increase in speed. The reverse option cause the prop to try to rotate the engine backwards. Since this is rather difficult there is a lot of pressure on all the gears and bearings and you get a slight decrease in speed. If this is all about speed under sail then just go out and buy a sailing prop and get rid of your motoring prop. They ALL have less drag and no wear while under sail. This is how the sailing bug creeps into your life. First it is "I have to get that prop to save my transmission". Later it becomes "I have to get that carbon-fiber mast to get my weight aloft down". And after a few races (formal or informal) "I really need that carbon-carbon-mylar mainsail to keep my flow from separating". ;-)
Transmission wear
Went to the Mack Boring school several years ago and they strongly recommended NOT to freewheel the prop while sailing. This accelerates wear of the transmission cone(s?). At that time they said the replacement part alone cost around $450!
Went to the Mack Boring school several years ago and they strongly recommended NOT to freewheel the prop while sailing. This accelerates wear of the transmission cone(s?). At that time they said the replacement part alone cost around $450!
MaxProp
it is inherent that the prop will not spin when it feathers. Not sure if that answers your question Waldo.
it is inherent that the prop will not spin when it feathers. Not sure if that answers your question Waldo.
MAX PROP SPIN
Yes, I do not put the max prop in reverse. I was told at a boat show that it is not necessary. Thanks for the comments.
Yes, I do not put the max prop in reverse. I was told at a boat show that it is not necessary. Thanks for the comments.
Our Max Prop spins like crazy in neutral.
So much so that it's very loud. We have to put the trany in reverse. It's not an option.
So much so that it's very loud. We have to put the trany in reverse. It's not an option.
Max Prop feathering
The mfg recommends the best way to ensure that the maxprop feathers is to leave the transmission in fwd gear when you shut down the engine and immediately thereafter shift into neutral. I don't always do that and when I forget, the prop continues to spin so it sounds to me like they know what works.
The mfg recommends the best way to ensure that the maxprop feathers is to leave the transmission in fwd gear when you shut down the engine and immediately thereafter shift into neutral. I don't always do that and when I forget, the prop continues to spin so it sounds to me like they know what works.
Hold on Don.
You have a Max Prop, right? Max props feather, (we all know that's true) A Max Prop rotating can only do so when the blades are at an angle. Blades at an angle mean the Max Prop is not feathered as designed. The slip-steam of water past the blades of a Max Prop cause the blades to feather. That can only happen when the prop is locked. But I could be wrong. I've only had mine since 1993.
You have a Max Prop, right? Max props feather, (we all know that's true) A Max Prop rotating can only do so when the blades are at an angle. Blades at an angle mean the Max Prop is not feathered as designed. The slip-steam of water past the blades of a Max Prop cause the blades to feather. That can only happen when the prop is locked. But I could be wrong. I've only had mine since 1993.
Hold on Don.
You have a Max Prop, right? Max props feather, (we all know that's true) A Max Prop rotating can only do so when the blades are at an angle. Blades at an angle mean the Max Prop is not feathered as designed. The slip-steam of water past the blades of a Max Prop cause the blades to feather. That can only happen when the prop is locked. But I could be wrong. I've only had mine since 1993.
You have a Max Prop, right? Max props feather, (we all know that's true) A Max Prop rotating can only do so when the blades are at an angle. Blades at an angle mean the Max Prop is not feathered as designed. The slip-steam of water past the blades of a Max Prop cause the blades to feather. That can only happen when the prop is locked. But I could be wrong. I've only had mine since 1993.
Fred
My maxprop feathers in neutral. Leaving it in gear will make it stop spinning but won't allow it to feather. To prove the point, next time your boat is out of the water, immobilize the shaft and try feathering the blades - they won't move.
My maxprop feathers in neutral. Leaving it in gear will make it stop spinning but won't allow it to feather. To prove the point, next time your boat is out of the water, immobilize the shaft and try feathering the blades - they won't move.
That's Fun, Don and Fred ;D
Didn't think you both could be right, but here is a quote from the installation manual (of the newer one which has the in-the-water adjustment feature): "4) PROPELLER USE The Max Prop works automatically. By putting the engine in gear the blades will engage in either forward or reverse. The best way to feather the propeller is; Power at 2 to 3 knots in forward. Kill the engine while still engaged in forward. When the engine has stopped, if the shaft is still spinning engage the transmission in reverse to stop the freewheeling. You can check to see if the propeller is feathered or not by taking the engine out of gear. If the propeller is not feathered the shaft will freewheel like with a fixed blade propeller. In that case start the engine again and repeat the three steps. If your propeller has been greased properly it will feather in a fraction of a second as soon as you stop the shaft from freewheeling. Once the prop is feathered, you can either leave the transmission in gear or out of gear, it does not matter. DO NOT kill the engine while in reverse. In this case the blades will be in the reverse position and will not feather. You can actually use this feature to drive a shaft alternator. IMPORTANT: If the Max-Prop is installed on a vessel that can attain sailing speeds over 15 knots, it is MANDATORY to return the transmission to neutral while sailing. If the transmission remains engaged and the propeller were to open (from hitting an object or water flow) it may turn the engine, flooding it, resulting damage to the engine."
Didn't think you both could be right, but here is a quote from the installation manual (of the newer one which has the in-the-water adjustment feature): "4) PROPELLER USE The Max Prop works automatically. By putting the engine in gear the blades will engage in either forward or reverse. The best way to feather the propeller is; Power at 2 to 3 knots in forward. Kill the engine while still engaged in forward. When the engine has stopped, if the shaft is still spinning engage the transmission in reverse to stop the freewheeling. You can check to see if the propeller is feathered or not by taking the engine out of gear. If the propeller is not feathered the shaft will freewheel like with a fixed blade propeller. In that case start the engine again and repeat the three steps. If your propeller has been greased properly it will feather in a fraction of a second as soon as you stop the shaft from freewheeling. Once the prop is feathered, you can either leave the transmission in gear or out of gear, it does not matter. DO NOT kill the engine while in reverse. In this case the blades will be in the reverse position and will not feather. You can actually use this feature to drive a shaft alternator. IMPORTANT: If the Max-Prop is installed on a vessel that can attain sailing speeds over 15 knots, it is MANDATORY to return the transmission to neutral while sailing. If the transmission remains engaged and the propeller were to open (from hitting an object or water flow) it may turn the engine, flooding it, resulting damage to the engine."
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