As a novice to sailing I'm confused by all the recommendations. I have a B331 with the stock 2 blade prop. I have a "very" tight slip that I definately need to back into and understand 3 blade is the way to go. Everything I read says Maxprop or Autoprop. Autoprop suggested a H5-416mm for the Westerbeake 30.(2.47:1 gear ratio and 25mm shaft. I like the idea of not having to adjust it, since I want to install it myself and I understand it auto adjusts. I'm not sure what the spec is for Max Prop but, I read lots about them need to be adjusted for the boat. Once this baby's back in the water I don't want to be pulling it out to play with a prop. What is the real difference?
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My take on Max vs. Autoprop
Rich, in a nutshell all that I have read, heard, and experienced leads me to suggest that if you sail most and motor least that the Max-Prop might be better for you as its symetrical blades, allow it to feather to a slightly more slippery configuration under sail, resulting in less drag. If on the other hand you motor more than sail, then the Autoprop might have the edge as its shape is slightly more efficient under power due to the fact that its blades are assymetrical (read: more hydrodynamicly efficient). That same assymetrical shape seems create slightly more drag under sail though, so........ To the best of my understanding it is almost a toss-up. My 3 blade Max-Prop has served me flawlessly for 5 years now. It gives excellent thrust in both forward and reverse. With regard to maintenance, I haul once/year, polishing and greasing it each time. A truly excellent piece of gear. I have a friend with an Autoprop who has nothing but good things to say about it as well. I think that perhaps the primary use of your boat should be the deciding factor between the two. In my opinion, you can't go wrong with either one. All Good Wishes! Ron Hughes s/v "Best Revenge" H 40.5
Rich, in a nutshell all that I have read, heard, and experienced leads me to suggest that if you sail most and motor least that the Max-Prop might be better for you as its symetrical blades, allow it to feather to a slightly more slippery configuration under sail, resulting in less drag. If on the other hand you motor more than sail, then the Autoprop might have the edge as its shape is slightly more efficient under power due to the fact that its blades are assymetrical (read: more hydrodynamicly efficient). That same assymetrical shape seems create slightly more drag under sail though, so........ To the best of my understanding it is almost a toss-up. My 3 blade Max-Prop has served me flawlessly for 5 years now. It gives excellent thrust in both forward and reverse. With regard to maintenance, I haul once/year, polishing and greasing it each time. A truly excellent piece of gear. I have a friend with an Autoprop who has nothing but good things to say about it as well. I think that perhaps the primary use of your boat should be the deciding factor between the two. In my opinion, you can't go wrong with either one. All Good Wishes! Ron Hughes s/v "Best Revenge" H 40.5
Max Prop for me
Two reasons. 1. Ron Hughes has it exactly right. The Max-Prop feathers better and is therefore preferable if you want to pick up more speed. 2. One side of the Auto Prop will have a tendency to flop downward if the shaft stops while the two props are in and up and down position. Momentum under sail will mitigate against the drop-down angle, but hey it's unnecessary resistence. (To understand this better, just go to your yard and check out the Auto-Props already installed to see how the flop downward.) It's true the Max-Prop takes a precise angle. All I did was have the mechanic on hand at launch and let him take a short spin. Within minutes he determined the corrected angle and pulled the boat with the same crew still in place. No charge. I'm a happy Max-Prop user and have no vested interest. In fact, my yard won't install the dripless packing gland made by the Max-Prop company and others because they don't trust them. By coincidence, a debate on this is raging in a related post made in the past day or two.
Two reasons. 1. Ron Hughes has it exactly right. The Max-Prop feathers better and is therefore preferable if you want to pick up more speed. 2. One side of the Auto Prop will have a tendency to flop downward if the shaft stops while the two props are in and up and down position. Momentum under sail will mitigate against the drop-down angle, but hey it's unnecessary resistence. (To understand this better, just go to your yard and check out the Auto-Props already installed to see how the flop downward.) It's true the Max-Prop takes a precise angle. All I did was have the mechanic on hand at launch and let him take a short spin. Within minutes he determined the corrected angle and pulled the boat with the same crew still in place. No charge. I'm a happy Max-Prop user and have no vested interest. In fact, my yard won't install the dripless packing gland made by the Max-Prop company and others because they don't trust them. By coincidence, a debate on this is raging in a related post made in the past day or two.
Autoprop
have an autoprop on my 410 and love it. Regarding Bill's observation about the prop angle, he's correct when they're on the hard, however, autoprop recommends having the shaft locked when sailing. This causes the blades to feather against the resistance of the water so I don't think there's much diffeerence in resistance. IMHO the auto pitching feature will lead to more acceleration and stopping power, since the prop is always perfectly pitched for boat speed, water conditions and current and the like. Never had a MaxpProp, but hear lots of good things about them. Bryce S/V Spellbinder
have an autoprop on my 410 and love it. Regarding Bill's observation about the prop angle, he's correct when they're on the hard, however, autoprop recommends having the shaft locked when sailing. This causes the blades to feather against the resistance of the water so I don't think there's much diffeerence in resistance. IMHO the auto pitching feature will lead to more acceleration and stopping power, since the prop is always perfectly pitched for boat speed, water conditions and current and the like. Never had a MaxpProp, but hear lots of good things about them. Bryce S/V Spellbinder
Take a look at J-Prop
I researched the comparison between Autoprop and Maxprop endlessly last year, talked to representatives of both products, etc. There is a big price difference between them, and if it is a tossup otherwise, then price alone will suggest the Maxprop. However, I stumbled upon a different brand of feathering propeller, called the J-prop. It is very similar to the Maxprop, eith one HUGE advantage: The J-prop permits pitch adjustment with the boat in the water; all you do is turn a dial to set a different pitch. Maxprop has this feature available only on props too large for my boat, and the cost is also much greater. I bought the J-prop for my Catalina 30 at a price just under what the comparable Maxprop costs, and I now have a prop that I can easily adjust the pitch. This might not seem like a big deal, until you realize that the alternative is to pay for a haulout. After one season, I am pleased with the J-prop. It added about 0.5 knots under sail, and the motoring performance is very similar to what I had with a fixed prop, with one exception: thrust in reverse is far better.
I researched the comparison between Autoprop and Maxprop endlessly last year, talked to representatives of both products, etc. There is a big price difference between them, and if it is a tossup otherwise, then price alone will suggest the Maxprop. However, I stumbled upon a different brand of feathering propeller, called the J-prop. It is very similar to the Maxprop, eith one HUGE advantage: The J-prop permits pitch adjustment with the boat in the water; all you do is turn a dial to set a different pitch. Maxprop has this feature available only on props too large for my boat, and the cost is also much greater. I bought the J-prop for my Catalina 30 at a price just under what the comparable Maxprop costs, and I now have a prop that I can easily adjust the pitch. This might not seem like a big deal, until you realize that the alternative is to pay for a haulout. After one season, I am pleased with the J-prop. It added about 0.5 knots under sail, and the motoring performance is very similar to what I had with a fixed prop, with one exception: thrust in reverse is far better.
I know whats better!!! 
Hello Rich, The Max-Prop needed for your 331 is a 17” two blade set to 14 degrees blade angle, bored to a 25mm Italia/ISO taper. If you would like to hear my opinions about my Max-Prop and how it differs to the Auto-Prop, please feel free to contact me. kwoody@pyiinc.com 800-523-7558. Hope this helps you
Hello Rich, The Max-Prop needed for your 331 is a 17” two blade set to 14 degrees blade angle, bored to a 25mm Italia/ISO taper. If you would like to hear my opinions about my Max-Prop and how it differs to the Auto-Prop, please feel free to contact me. kwoody@pyiinc.com 800-523-7558. Hope this helps you
I have tried both...
Autoprop Con: The size recommended by the Autoprop company was obviously derived from a formula because it didn't fit my boat (too large). There was not enough clearance between the blade tips and the hull. Also, the shaft strut had to be modified to allow clearance when shifting from forward to reverse. Overall result was excess vibration. The extra drag (compared to maxprop) was no more than one tenth of a knot. Autoprop Pro: Of the two the Autoprop was the faster, more powerful prop when motoring. Curved blade sections were much more efficient - I easily motored at hull speed with plenty of throttle to spare. Another advantage was motor-sailing. The self-pitching blades would bite the on-flowing water while slowly sailing with a huge amount of pitch. If the sails are pulling the boat at 3 kts, it would only take slightly above idle power to bring the boat up to 5 or 6 kts. Autoprop summary: In my opinion, Autoprop is the superior prop if you get a successful installation. Before ordering find someone else who is using one on a boat like yours and find out what fits. For the type of sailing I do I would rather have an Autoprop if one could be properly fitted to my 30 footer. Maxprop Con: Flat inefficient blades prevent my boat from reaching hull speed while motoring. (I have the 3 blade model). Setting the pitch to the setting that others use or what PYI recommends doesn't guarantee the optimum pitch for YOUR boat. Many people I have talked to required 3 different pitch adjustments to dial in the best setting for their boat. I have done 2 and am not happy with the performance yet. Too much pitch results in black smoke, overheating and not being able to achieve full rpm. Not enough pitch means you will not transmit full power into thrust. The best compromise seems to be a setting that results slightly less than full rpm (with high temp and slight smoke) while still not developing full thrust. The additional haul-outs for re-pitching negate any savings of the slightly lower cost maxprop. MaxProp says that their props can be adjusted in the water by a diver. It helps if you are in clear water with a sandy bottom that makes it easy to retrieve dropped parts. The entire prop has to be disassembled and re-assembled to re-pitch and all internal parts are coated in marine grease (very slippery). Another con: The flat blades have a sharp corner that cavitates at certain rpms. You can hear the loud gurgling at all rpms between 1200 and 2000 rpm, making about half of my power curve unusable. Maxprop Pro: Flat blades are slightly faster than Autoprop when sailing (Not much). Maxprop is lighter than Autoprop - the "clunk" of engaging in gear is much less with Maxprop and easier on the transmission. Maxprop is slightly cheaper than Autoprop. Maxprop Summary: PYI markets the maxprop but you can get it even cheaper from other distributors. The one I used (not PYI) offered 30 day satisfaction guarantee on everything they sold. I guess they were satisfied with my money because when I expressed my desire to return it they changed from friendly and helpful to quite the opposite. (They weren’t too happy that I had actually put it in the water!) They referred me to PYI and all requests for help from PYI were answered with the recommendation to re-pitch (again). I am disappointed with my Maxprop's powering performance. Perhaps it will improve with the next adjustment but it will have to wait until next haul out. Choose carefully. It sucks having nearly two thousand dollars invested in a prop you don’t like.
Autoprop Con: The size recommended by the Autoprop company was obviously derived from a formula because it didn't fit my boat (too large). There was not enough clearance between the blade tips and the hull. Also, the shaft strut had to be modified to allow clearance when shifting from forward to reverse. Overall result was excess vibration. The extra drag (compared to maxprop) was no more than one tenth of a knot. Autoprop Pro: Of the two the Autoprop was the faster, more powerful prop when motoring. Curved blade sections were much more efficient - I easily motored at hull speed with plenty of throttle to spare. Another advantage was motor-sailing. The self-pitching blades would bite the on-flowing water while slowly sailing with a huge amount of pitch. If the sails are pulling the boat at 3 kts, it would only take slightly above idle power to bring the boat up to 5 or 6 kts. Autoprop summary: In my opinion, Autoprop is the superior prop if you get a successful installation. Before ordering find someone else who is using one on a boat like yours and find out what fits. For the type of sailing I do I would rather have an Autoprop if one could be properly fitted to my 30 footer. Maxprop Con: Flat inefficient blades prevent my boat from reaching hull speed while motoring. (I have the 3 blade model). Setting the pitch to the setting that others use or what PYI recommends doesn't guarantee the optimum pitch for YOUR boat. Many people I have talked to required 3 different pitch adjustments to dial in the best setting for their boat. I have done 2 and am not happy with the performance yet. Too much pitch results in black smoke, overheating and not being able to achieve full rpm. Not enough pitch means you will not transmit full power into thrust. The best compromise seems to be a setting that results slightly less than full rpm (with high temp and slight smoke) while still not developing full thrust. The additional haul-outs for re-pitching negate any savings of the slightly lower cost maxprop. MaxProp says that their props can be adjusted in the water by a diver. It helps if you are in clear water with a sandy bottom that makes it easy to retrieve dropped parts. The entire prop has to be disassembled and re-assembled to re-pitch and all internal parts are coated in marine grease (very slippery). Another con: The flat blades have a sharp corner that cavitates at certain rpms. You can hear the loud gurgling at all rpms between 1200 and 2000 rpm, making about half of my power curve unusable. Maxprop Pro: Flat blades are slightly faster than Autoprop when sailing (Not much). Maxprop is lighter than Autoprop - the "clunk" of engaging in gear is much less with Maxprop and easier on the transmission. Maxprop is slightly cheaper than Autoprop. Maxprop Summary: PYI markets the maxprop but you can get it even cheaper from other distributors. The one I used (not PYI) offered 30 day satisfaction guarantee on everything they sold. I guess they were satisfied with my money because when I expressed my desire to return it they changed from friendly and helpful to quite the opposite. (They weren’t too happy that I had actually put it in the water!) They referred me to PYI and all requests for help from PYI were answered with the recommendation to re-pitch (again). I am disappointed with my Maxprop's powering performance. Perhaps it will improve with the next adjustment but it will have to wait until next haul out. Choose carefully. It sucks having nearly two thousand dollars invested in a prop you don’t like.
I have an Autoprop on a "99 Cat 36MKII
And I am "basically" very satisfied with my autoprop.....if you are not a "pure Sailboat Racer"....then go with the autoprop....its basically the same price....but SO MUCH more efficient!....It is self adjusting to the proper pitch ALL THE TIME....not just in a certain engine RPM...no Re-pitching ---EVER! If I wanted to win sailboat races......then I would go go with the Maxi-Prop...I think Rick was being kind.....maybe when the wind is blowing....its only a .1 knot difference......but in light air I think it might be more....but you would only notice if you were a pure racer..............if not, you WILL NOT notice......
And I am "basically" very satisfied with my autoprop.....if you are not a "pure Sailboat Racer"....then go with the autoprop....its basically the same price....but SO MUCH more efficient!....It is self adjusting to the proper pitch ALL THE TIME....not just in a certain engine RPM...no Re-pitching ---EVER! If I wanted to win sailboat races......then I would go go with the Maxi-Prop...I think Rick was being kind.....maybe when the wind is blowing....its only a .1 knot difference......but in light air I think it might be more....but you would only notice if you were a pure racer..............if not, you WILL NOT notice......
How about barnicle
I appreciate all the good input on the two props. My concern is that would barnicle growth or fouling from slime get in the way of either max or auto prop functioning properly, especially Autoprop. Any input on that? Thanks Good Winds Dave
I appreciate all the good input on the two props. My concern is that would barnicle growth or fouling from slime get in the way of either max or auto prop functioning properly, especially Autoprop. Any input on that? Thanks Good Winds Dave
Well I sail on Long Island Sound and Haven't had
any problems with the Autoprop and I don't think you ever will. The Autoprop has the three blades constantly twisting in their bearing races (at least a little) even at the dock.....Even if there was some kind of growth the way the Autoprop works would automatically "grind" whatever was in there away....... I wouldn't have any concerns.......now a barnacle on the actually blade of the propeller.....well thats something we all have to deal with in our oun way..;-)
any problems with the Autoprop and I don't think you ever will. The Autoprop has the three blades constantly twisting in their bearing races (at least a little) even at the dock.....Even if there was some kind of growth the way the Autoprop works would automatically "grind" whatever was in there away....... I wouldn't have any concerns.......now a barnacle on the actually blade of the propeller.....well thats something we all have to deal with in our oun way..;-)
prop fouling
Dave, I sail out of Boston on my H410 with an autoprop and have no types of fouling problems in three years of use. Bryce S/V Spellbinder H410
Dave, I sail out of Boston on my H410 with an autoprop and have no types of fouling problems in three years of use. Bryce S/V Spellbinder H410
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