I recently purchased a 85 Hunter 31. The previous owner raced the boat almost exclusively. He fitted the boat w/ a folding prop. To it seems to go forward okay, but it doesnt have hardly any reverse or stopping power. Do all folding props have these characteristics? If so, would the original type prop be a better choice for me since I do not race & need better handling under power? How much are propellers & where could you find one for this boat? Thanks for any replies.
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Scot Fraser
Similar prop problem
I've just purchased a 1983 Hunter 31, which has the standard fixed 2-blade prop and the reverse thrust is very unimpressive. I'm wondering if a 3-blade prop would make a significant differance. Anyone know?
I've just purchased a 1983 Hunter 31, which has the standard fixed 2-blade prop and the reverse thrust is very unimpressive. I'm wondering if a 3-blade prop would make a significant differance. Anyone know?
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Tim Leighton
PROPELLER
John/Scot: Both of you should have good prop shops in your sailing areas. The price you pay for folding props is poor reverse performance. By then again, how often do you sail backwards? All kidding aside, think long and hard about dumping a folding prop (I don't have one, but am looking) since it can provide a significant (around 10%) increase in sailing speed/loss of drag. As for a 3 bladed prop, I wasn't aware that one was ever offered for the 31. If you do a LOT of motoring, a 3 may be a good choice, but I'd be curious if any 3's are correctly sized/pitched for our 3GMF's. Besides, a "3" just means another blade to scrape! Those of us with "older" 31's are plagued with undersized engines, but just remember that a different prop (or at least one which is not properly sized for your engine) may cause more harm than good. Hope this helps. Tim L. (S/V "TIDE")
John/Scot: Both of you should have good prop shops in your sailing areas. The price you pay for folding props is poor reverse performance. By then again, how often do you sail backwards? All kidding aside, think long and hard about dumping a folding prop (I don't have one, but am looking) since it can provide a significant (around 10%) increase in sailing speed/loss of drag. As for a 3 bladed prop, I wasn't aware that one was ever offered for the 31. If you do a LOT of motoring, a 3 may be a good choice, but I'd be curious if any 3's are correctly sized/pitched for our 3GMF's. Besides, a "3" just means another blade to scrape! Those of us with "older" 31's are plagued with undersized engines, but just remember that a different prop (or at least one which is not properly sized for your engine) may cause more harm than good. Hope this helps. Tim L. (S/V "TIDE")
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Scott Fraser
Prop info Hunter 31
Talk about timeing. I just recevied the latest issue of Practical Sailor, and someone asked the Advisor that very question. Here's the question and answer: Propeller Alternatives You have done two excellent articles comparing the relative performance characteristics of various types of small boat propellers (Oct 1, 1993 and January 1, 1995). From those articles and the other reading that I have done, I have concluded that the best propeller to replace the existing folding one on my 35-foot sloop is a feathering propeller. The issue I am having trouble resolving is the benefit of a three-blade feathering propeller over a two- blade one. The boat is underpowered by today’s standards, therefore I want to maximize the engine performance. My question is whether, for a given horsepower and engine RPM, a three-blade feathering propeller will drive the boat at a higher speed than a two- blade propeller? In adverse conditions (wind, seas) will the three-blade propeller outperform the two-blade? -James D. Phyfe III, Hong Kong A three-bladed prop will produce stronger, smoother thrust than a two-bladed prop, which means it will be better at pushing the boat into strong headwinds and chop. Feathering props are a bit less efficient than fixed-blade props at driving the boat forward, mainly because they have less twist built in so that they present less drag when feathered. Even so, a feathering three-blade should be more efficient than a fixed two-blade, and a lot better in reverse. Boatspeed is another question with more components. If, for example, your boat’s maximum hull speed is 7 knots and you can reach that speed in flat water with your two-bladed prop, you’ll probably be able to reach it more easily with the three-bladed prop at the same RPM, and cruise at 6 knots at a lower RPM (depending on how your engine is geared). The three-bladed prop won’t have much of an effect on top speed in flat water, although it might muscle the boat ahead a bit faster at the cost of fuel and engine wear. Again, it will be a good deal better at getting you home in a headwind. You should check with an expert to make sure your engine is geared right for the prop in question. We have a good shop here in Connecticut called the Essex Machine Works. Number: 800/724-0528. You can ask for Bob Claps. Also, read Dave Gerr’s definitive Propeller Handbook, available from International Marine Publishers at 800/262-4729. -------------------------- That was interesting. Today, I just happened to drive by a prop shop and went in to talk with the folks. I learned a three blade prop will significantly increase the thrust at low speed, and provide more power/speed using less fuel. I also learned there are different props for sailboats and motorboats. The ones for sailboats have a teardrop shape to the blades. A motorboat prop will provide even greater performance than a sailing prop, but with greater drag. However, my boat is so underpowered with the 2GM engine that I'm seriously considering the motorboat prop. I know this is tanamount to a sailor's sin, but right now the lack of thrust is dangerous. Maybe a 3-blade sailing prop will be good enough, but I don't have a lot of money to play with and can't keep trying props till I find one that works right. Scott Fraser Harborage Marina; Slip A-21 1110 3rd St. So. St. Petersburg, FL 33701-5525
Talk about timeing. I just recevied the latest issue of Practical Sailor, and someone asked the Advisor that very question. Here's the question and answer: Propeller Alternatives You have done two excellent articles comparing the relative performance characteristics of various types of small boat propellers (Oct 1, 1993 and January 1, 1995). From those articles and the other reading that I have done, I have concluded that the best propeller to replace the existing folding one on my 35-foot sloop is a feathering propeller. The issue I am having trouble resolving is the benefit of a three-blade feathering propeller over a two- blade one. The boat is underpowered by today’s standards, therefore I want to maximize the engine performance. My question is whether, for a given horsepower and engine RPM, a three-blade feathering propeller will drive the boat at a higher speed than a two- blade propeller? In adverse conditions (wind, seas) will the three-blade propeller outperform the two-blade? -James D. Phyfe III, Hong Kong A three-bladed prop will produce stronger, smoother thrust than a two-bladed prop, which means it will be better at pushing the boat into strong headwinds and chop. Feathering props are a bit less efficient than fixed-blade props at driving the boat forward, mainly because they have less twist built in so that they present less drag when feathered. Even so, a feathering three-blade should be more efficient than a fixed two-blade, and a lot better in reverse. Boatspeed is another question with more components. If, for example, your boat’s maximum hull speed is 7 knots and you can reach that speed in flat water with your two-bladed prop, you’ll probably be able to reach it more easily with the three-bladed prop at the same RPM, and cruise at 6 knots at a lower RPM (depending on how your engine is geared). The three-bladed prop won’t have much of an effect on top speed in flat water, although it might muscle the boat ahead a bit faster at the cost of fuel and engine wear. Again, it will be a good deal better at getting you home in a headwind. You should check with an expert to make sure your engine is geared right for the prop in question. We have a good shop here in Connecticut called the Essex Machine Works. Number: 800/724-0528. You can ask for Bob Claps. Also, read Dave Gerr’s definitive Propeller Handbook, available from International Marine Publishers at 800/262-4729. -------------------------- That was interesting. Today, I just happened to drive by a prop shop and went in to talk with the folks. I learned a three blade prop will significantly increase the thrust at low speed, and provide more power/speed using less fuel. I also learned there are different props for sailboats and motorboats. The ones for sailboats have a teardrop shape to the blades. A motorboat prop will provide even greater performance than a sailing prop, but with greater drag. However, my boat is so underpowered with the 2GM engine that I'm seriously considering the motorboat prop. I know this is tanamount to a sailor's sin, but right now the lack of thrust is dangerous. Maybe a 3-blade sailing prop will be good enough, but I don't have a lot of money to play with and can't keep trying props till I find one that works right. Scott Fraser Harborage Marina; Slip A-21 1110 3rd St. So. St. Petersburg, FL 33701-5525
Don't see anything very positive about a folder!
I do not see much positive about a folder, other than sailing faster. We have a two blade CDI which is suppose to be engineered for the 2GM engine. I think ours is 15x10 or 11. It works OK. I do not find the H'31 underpowered most of the time. We can crank her up to hull speed without any problems. We are going to try a Kilian 2 blade prop when we pull the boat later this year. It is a very good compromise in my opinion. They have some special tricks that make a two blade prop back up without prop walk (three blade prop makes prop walk worse) and give you more thrust in forward (all for about $130) on your existing prop. If you look up Kilian in the archives you should get some feed back on these props. Kilian is located in San Leandro, Ca. A/C 510 (sorry don't have their entire phone number)
I do not see much positive about a folder, other than sailing faster. We have a two blade CDI which is suppose to be engineered for the 2GM engine. I think ours is 15x10 or 11. It works OK. I do not find the H'31 underpowered most of the time. We can crank her up to hull speed without any problems. We are going to try a Kilian 2 blade prop when we pull the boat later this year. It is a very good compromise in my opinion. They have some special tricks that make a two blade prop back up without prop walk (three blade prop makes prop walk worse) and give you more thrust in forward (all for about $130) on your existing prop. If you look up Kilian in the archives you should get some feed back on these props. Kilian is located in San Leandro, Ca. A/C 510 (sorry don't have their entire phone number)
J
John
New ad in SAIL magazine
The new issue of SAIL magazine has a new ad in the back of a company called Perfect Pitch Propellers. They make propellers for several yanmar engines. They claim to have tested these props so we dont have to. So i plan to call them and find out more info when i get back to my boat and get the magazine. Thanks for all the previous responses.
The new issue of SAIL magazine has a new ad in the back of a company called Perfect Pitch Propellers. They make propellers for several yanmar engines. They claim to have tested these props so we dont have to. So i plan to call them and find out more info when i get back to my boat and get the magazine. Thanks for all the previous responses.
John, I've got one!
John: I've got one. I have nothing bad to say about the prop. It was pitched slightly less than the stock prop so I am better RPM's. Had it for two years without any problems.
John: I've got one. I have nothing bad to say about the prop. It was pitched slightly less than the stock prop so I am better RPM's. Had it for two years without any problems.
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