Looking to purchase a folding prop. I have a 36' Beneteau with a 27 hp Yanmar. Please advise on which brands work best. How much do they cost? Where can I buy them? How much faster will my boat sail with one? Thanks
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Nautilas
Try Nautilas Propellers in Toronto. When you speak with them, tell them that his customers from the East Coast recommended them. A friend and ourselves purchased new props last season. One for a C&C and the other for our Hunter. Great!!!!!!!!!
Try Nautilas Propellers in Toronto. When you speak with them, tell them that his customers from the East Coast recommended them. A friend and ourselves purchased new props last season. One for a C&C and the other for our Hunter. Great!!!!!!!!!
Max Prop
I use a max prop for my Cal 33, which is powered by a 27hp Yanmar. I feel less vibration under power, an increased sailing speed, and install and price were both easy. Max-Prop Propeller 12532 Beverly Park Rd. Lynnwood, WA 98037 Toll Free: 800-523-7558 Fax: 425-355-3661
I use a max prop for my Cal 33, which is powered by a 27hp Yanmar. I feel less vibration under power, an increased sailing speed, and install and price were both easy. Max-Prop Propeller 12532 Beverly Park Rd. Lynnwood, WA 98037 Toll Free: 800-523-7558 Fax: 425-355-3661
Feathering vs Folding
Before I bought a prop for my B361, I gave some thought to the different folding and feathering props available. In addition to price, there are four major considerations to evaluate a prop: Thrust, Efficiency, Drag, and Serviceability. Feathering vs Folding Folding allows the prop blades to have a twist without necessarily increasing drag. Twist is needed because as the blade rotates, its local speed increases with the distance from the shaft center of rotation. Thus, to maintain a constant angle of attack relative to the incoming water, the blade pitch needs to be progressively reduced, hence the twist in the blades. Feathering props, such as the MaxProp or the Kiwi, have no twist and thus are substantially less efficient than folding props; "The tradeoff for any flat blade design (required for the feathering function) as boat speed increases is a fall in relative efficiency." (From Kiwi website). The self pitching Autoprop does have a twist and higher efficiency but at much higher drag cost. Translated, for a tank of fuel you will get a longer range with a folding prop. This is important for those planning long passages, like me. If you have a large fuel tank and are not planning long passages, feathering props may be for you but don't overlook the yearly maintenance involved. Two vs three blades. Unless you are a devoted racer, the additional gain in reduced friction from a 3 blade to a 2 blade prop, does not justify the reduction in thrust of the 2 blade. Translated, the 3 blade will work better against heavy chop and, given a proper design, will add minimal drag. The three-blade folding props I considered were the Gori, the Flex-o-fold, and the Volvo. Of these, the Flex-o-fold appeared to have the best efficiency, followed by the Volve and the Gori. However, in the Volvo efficiency came at the expense of a substantial increase in drag, based on the German Study cited by the Flex-O-Fold website. I concluded that both the Gori and the Fexofold were excellent choices but each required a compromise. Although very similar in concept, there are two important differences between these props. Both props have the twist in pitch that you see in fixed blade props. Because the shape of the FlexoFold blade is closer to that of a fix blade prop (thinner blades and more twist) and not surprisingly it is 10% more efficient than the 3-blade Gori (German study). Balancing that, the Gori 3-blade has two features that are unique. One, the prop has what they call an overdrive configuration. When you power the prop with the boat at rest the blades rotate so that their leading edge remains the same in forward and reverse. This rotation of the blade is similar to that of the MaxProp and other feathering props and claimed to improve the prop-walk in reverse (I don't buy it, most of the prop walk comes from the inclination of the shaft away from to the horizontal line.) In the Gori 3-blade prop, during the change from reverse to forward while the boat is still moving in reverse, the pressure of the water keeps the prop unfolded in the reverse configuration as it begins to rotate in the forward direction. Because the pitch is higher in the reverse configuration compared with that in forward configuration, this gives the prop a more effective pitch for motor-sailing where the sails are helping the prop. A second difference between Gori (left on PIX) and Fex-o-Fold (right on PIX) is the configuration of the prop in the folded state The Gori-3 keeps the folded blades in a radial direction relative to the shaft, while the Flexofold keeps the blades in a circumferential direction. Clearly, the total area presented by the folded prop is greater in a FexOFold than a Gori and thus the friction should be somewhat higher. More importantly, as the Gori begins to rotate, the water pressure acts on the blades surfaces and pushes them to unfold. This effect occurs equally in the forward and reverse directions. As the blades unfold, increasing centrifugal force takes over and finishes the job. This leads to a smooth transition from rest to motion whether forward or in reverse. More important, it provides you with the certainty that the blades will unfold when you need it without having to over-rev the engine!!! (ie; when you need to stop before you hit something). In contrast, the Flexofold 3-blade, as most 2-blade folding props, counts almost exclusively on centrifugal force to unfold. As a result, the shaft has to turn at quite a bit of speed before the blades begin to unfold and when they do it, they do it with a big bang!. Not that it matters if you get used to it, but to me having the extra force of the water unfolding the blades gives me an extra sense of security. I supose that by now you figured what was my choice. Fair winds
Before I bought a prop for my B361, I gave some thought to the different folding and feathering props available. In addition to price, there are four major considerations to evaluate a prop: Thrust, Efficiency, Drag, and Serviceability. Feathering vs Folding Folding allows the prop blades to have a twist without necessarily increasing drag. Twist is needed because as the blade rotates, its local speed increases with the distance from the shaft center of rotation. Thus, to maintain a constant angle of attack relative to the incoming water, the blade pitch needs to be progressively reduced, hence the twist in the blades. Feathering props, such as the MaxProp or the Kiwi, have no twist and thus are substantially less efficient than folding props; "The tradeoff for any flat blade design (required for the feathering function) as boat speed increases is a fall in relative efficiency." (From Kiwi website). The self pitching Autoprop does have a twist and higher efficiency but at much higher drag cost. Translated, for a tank of fuel you will get a longer range with a folding prop. This is important for those planning long passages, like me. If you have a large fuel tank and are not planning long passages, feathering props may be for you but don't overlook the yearly maintenance involved. Two vs three blades. Unless you are a devoted racer, the additional gain in reduced friction from a 3 blade to a 2 blade prop, does not justify the reduction in thrust of the 2 blade. Translated, the 3 blade will work better against heavy chop and, given a proper design, will add minimal drag. The three-blade folding props I considered were the Gori, the Flex-o-fold, and the Volvo. Of these, the Flex-o-fold appeared to have the best efficiency, followed by the Volve and the Gori. However, in the Volvo efficiency came at the expense of a substantial increase in drag, based on the German Study cited by the Flex-O-Fold website. I concluded that both the Gori and the Fexofold were excellent choices but each required a compromise. Although very similar in concept, there are two important differences between these props. Both props have the twist in pitch that you see in fixed blade props. Because the shape of the FlexoFold blade is closer to that of a fix blade prop (thinner blades and more twist) and not surprisingly it is 10% more efficient than the 3-blade Gori (German study). Balancing that, the Gori 3-blade has two features that are unique. One, the prop has what they call an overdrive configuration. When you power the prop with the boat at rest the blades rotate so that their leading edge remains the same in forward and reverse. This rotation of the blade is similar to that of the MaxProp and other feathering props and claimed to improve the prop-walk in reverse (I don't buy it, most of the prop walk comes from the inclination of the shaft away from to the horizontal line.) In the Gori 3-blade prop, during the change from reverse to forward while the boat is still moving in reverse, the pressure of the water keeps the prop unfolded in the reverse configuration as it begins to rotate in the forward direction. Because the pitch is higher in the reverse configuration compared with that in forward configuration, this gives the prop a more effective pitch for motor-sailing where the sails are helping the prop. A second difference between Gori (left on PIX) and Fex-o-Fold (right on PIX) is the configuration of the prop in the folded state The Gori-3 keeps the folded blades in a radial direction relative to the shaft, while the Flexofold keeps the blades in a circumferential direction. Clearly, the total area presented by the folded prop is greater in a FexOFold than a Gori and thus the friction should be somewhat higher. More importantly, as the Gori begins to rotate, the water pressure acts on the blades surfaces and pushes them to unfold. This effect occurs equally in the forward and reverse directions. As the blades unfold, increasing centrifugal force takes over and finishes the job. This leads to a smooth transition from rest to motion whether forward or in reverse. More important, it provides you with the certainty that the blades will unfold when you need it without having to over-rev the engine!!! (ie; when you need to stop before you hit something). In contrast, the Flexofold 3-blade, as most 2-blade folding props, counts almost exclusively on centrifugal force to unfold. As a result, the shaft has to turn at quite a bit of speed before the blades begin to unfold and when they do it, they do it with a big bang!. Not that it matters if you get used to it, but to me having the extra force of the water unfolding the blades gives me an extra sense of security. I supose that by now you figured what was my choice. Fair winds
Flex-o-fold after 1 season
This spring I purchased a used Beneteau 351 and had previously used a folding 2 blad Martec. I chose the Flex-o-fold and have loved it both sailing in powering. The only problem was to get the correct pitch I had to change out the first blades and change them. Have had not problems and would highly recomend it.
This spring I purchased a used Beneteau 351 and had previously used a folding 2 blad Martec. I chose the Flex-o-fold and have loved it both sailing in powering. The only problem was to get the correct pitch I had to change out the first blades and change them. Have had not problems and would highly recomend it.
Sixth season w/Flex-O-Fold.
I replaced the original 2-blade with a Flex-O-Fold 2-blade in 1999. I have never had a problem. Forward power is better and reverse is slightly better. It does not solve prop walk however. It is probably worth a half a knot SOG above six knots. My boat is underpowered, 20hp and 18000# displacement. Still it easily cruises at 6 knots around 2400 rpm. Given my experience I would opt for the 3-blade next time. I think it would help prop walk and provide more power in strong currents and waves.
I replaced the original 2-blade with a Flex-O-Fold 2-blade in 1999. I have never had a problem. Forward power is better and reverse is slightly better. It does not solve prop walk however. It is probably worth a half a knot SOG above six knots. My boat is underpowered, 20hp and 18000# displacement. Still it easily cruises at 6 knots around 2400 rpm. Given my experience I would opt for the 3-blade next time. I think it would help prop walk and provide more power in strong currents and waves.
Seahawk Slipstream Stainless Folder...
...is what I put on my Nonsuch. Perfect performance in both forward and reverse with no discernable prop-walk. I purchased mine from H&H Propeller in Essex, CT (they have an office in Salem, MA as well) and they were wonderful to deal with. You can contact H&H at www.handhprop.com and ask for Jim Blanchard. You can see the prop on Seahawk's website (linkage below). This prop performs every bit as good as a fixed prop. It pushes me to hull speed effortlessly and stops the boat on a dime in reverse. Stainless, being much stronger than bronze, allows them to begin the pitch almost immediately from the hub which gives you that much more surface area to bit with. With weaker metals, the pitch can't begin too close to the hub because the blades have to be a bit thicker throughout their entire length due to the inherent weakness in the metal. When opened, the Slipstream folder looks exactly like a fixed prop. Both blades are geared to each other to ensure they open together. The prop is totally user maintainable and easy to install. It's available for both shaft drive and saildrive. Customer support from H&H is top-notch! I will NEVER mess with bronze props again! You can't beat stainless! Cheers, Bob
...is what I put on my Nonsuch. Perfect performance in both forward and reverse with no discernable prop-walk. I purchased mine from H&H Propeller in Essex, CT (they have an office in Salem, MA as well) and they were wonderful to deal with. You can contact H&H at www.handhprop.com and ask for Jim Blanchard. You can see the prop on Seahawk's website (linkage below). This prop performs every bit as good as a fixed prop. It pushes me to hull speed effortlessly and stops the boat on a dime in reverse. Stainless, being much stronger than bronze, allows them to begin the pitch almost immediately from the hub which gives you that much more surface area to bit with. With weaker metals, the pitch can't begin too close to the hub because the blades have to be a bit thicker throughout their entire length due to the inherent weakness in the metal. When opened, the Slipstream folder looks exactly like a fixed prop. Both blades are geared to each other to ensure they open together. The prop is totally user maintainable and easy to install. It's available for both shaft drive and saildrive. Customer support from H&H is top-notch! I will NEVER mess with bronze props again! You can't beat stainless! Cheers, Bob
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