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folding prop
Flex-o-fold and Varifold are, IMHO, the best designs. They are geared, which means that if one blade opens, they all must open. Also, the blades are designed so that the prop doesn't rely solely upon centrifugal force to open. The blades overlap just a bit, which allows water pressure to force open the blades.
Flex-o-fold and Varifold are, IMHO, the best designs. They are geared, which means that if one blade opens, they all must open. Also, the blades are designed so that the prop doesn't rely solely upon centrifugal force to open. The blades overlap just a bit, which allows water pressure to force open the blades.
folding vs. feathering
I neglected to mention that I've spent the past 6 months avidly researching folding and feathering propellers. For 7 years I had a feathering prop on my C30. Are you aware of the various tradeoffs between folding and feathering props?
I neglected to mention that I've spent the past 6 months avidly researching folding and feathering propellers. For 7 years I had a feathering prop on my C30. Are you aware of the various tradeoffs between folding and feathering props?
Folding vs Feathering
We are now using a fixed 3 blade prop and we would like to go to a folding or feathering prop. We are looking to get better sailing proformance out of our Catalina 30. The boat has a Universal 5411 11hp engine. We are not aware of the tradeoffs between a folding and feathering prop. Could you share your findings? We would appreciate your answers.
We are now using a fixed 3 blade prop and we would like to go to a folding or feathering prop. We are looking to get better sailing proformance out of our Catalina 30. The boat has a Universal 5411 11hp engine. We are not aware of the tradeoffs between a folding and feathering prop. Could you share your findings? We would appreciate your answers.
Tradeoffs
Folding propellers provide the least drag, in general, but especially on saildrive units. On boats with downward sloping propeller shafts, the feathering propeller may do very nearly as well as a folder. Folding propellers have had a history of nonreliability, because the older models rely entirely on centrifugal force to open. This is a real problem when going in reverse, because the flow of the water is against the blades that are trying to open. Many owners of folders know that they must rev the engine after putting it in gear to get the folder to open. The newer geared models from Flex-o-fold and Varifold are better, IMHO. However, marine growth can foul the exposed gears and inhibit the opening. So, it is a very good idea to occasionally check your folder if you let your boat sit for long periods. Folding props are fixed in pitch. Folding props close almost immediately after you shut down the engine and lock the transmission. Folding props cost significantly less and are simpler than feathering props, but they wear out considerably faster. Brands include Martec, Variprop, Gori, Flex-o-fold, etc. Feathering props cost a lot of money. There are several different models available. I have had a J-prop in the past and was quite satisfied with it for 7 years, but it ended up falling off my boat and being lost. I believe my yard quite likely did a shoddy job of installation. Variprop makes a beautiful design with separate adjustments for pitch in forward and reverse, so you can change your setting if you don't like it, even with the boat in the water (other feathering designs such as Maxprop may require a haulout to adjust pitch). Feathering props are very nearly as good in forward as are fixed props, and feathering props are better than any other prop in reverse thrust (which will be same as forward thrust). Feathering props therefore are terrific at stopping the boat, and terrific for slow speed maneuvering. Unlike folding props, feathering props open every time because their design forces them to open. Since they don't rely on centrifugal force, feathering props open even at very low RPM's. Feathering props "feather" when the engine is shut down and the transmission is locked, but they may require more boatspeed to feather than a folding prop needs to fold. However, once feathered, the prop stays that way until you use the engine again. There are no exposed gears to foul the prop, although I have heard of one case when a feathering prop that had sat all season in a high marine growth area was so fouled that it could not open. Brands include Maxprop, J-prop, Variprop, Luke, Hydralign, Autostream, and Autoprop.
Folding propellers provide the least drag, in general, but especially on saildrive units. On boats with downward sloping propeller shafts, the feathering propeller may do very nearly as well as a folder. Folding propellers have had a history of nonreliability, because the older models rely entirely on centrifugal force to open. This is a real problem when going in reverse, because the flow of the water is against the blades that are trying to open. Many owners of folders know that they must rev the engine after putting it in gear to get the folder to open. The newer geared models from Flex-o-fold and Varifold are better, IMHO. However, marine growth can foul the exposed gears and inhibit the opening. So, it is a very good idea to occasionally check your folder if you let your boat sit for long periods. Folding props are fixed in pitch. Folding props close almost immediately after you shut down the engine and lock the transmission. Folding props cost significantly less and are simpler than feathering props, but they wear out considerably faster. Brands include Martec, Variprop, Gori, Flex-o-fold, etc. Feathering props cost a lot of money. There are several different models available. I have had a J-prop in the past and was quite satisfied with it for 7 years, but it ended up falling off my boat and being lost. I believe my yard quite likely did a shoddy job of installation. Variprop makes a beautiful design with separate adjustments for pitch in forward and reverse, so you can change your setting if you don't like it, even with the boat in the water (other feathering designs such as Maxprop may require a haulout to adjust pitch). Feathering props are very nearly as good in forward as are fixed props, and feathering props are better than any other prop in reverse thrust (which will be same as forward thrust). Feathering props therefore are terrific at stopping the boat, and terrific for slow speed maneuvering. Unlike folding props, feathering props open every time because their design forces them to open. Since they don't rely on centrifugal force, feathering props open even at very low RPM's. Feathering props "feather" when the engine is shut down and the transmission is locked, but they may require more boatspeed to feather than a folding prop needs to fold. However, once feathered, the prop stays that way until you use the engine again. There are no exposed gears to foul the prop, although I have heard of one case when a feathering prop that had sat all season in a high marine growth area was so fouled that it could not open. Brands include Maxprop, J-prop, Variprop, Luke, Hydralign, Autostream, and Autoprop.
Options
Couple other options. The Campbell Sailor is a fixed design with narrow blades. Provides the same thrust as a standard sailor prop with less drag when sailing. Also the Kiwi. It is a feathering design with composite blades. Less expensive than the all metal feathering designs, it is getting good reviews. see them both at www.westbynorth.com (no affiliation)
Couple other options. The Campbell Sailor is a fixed design with narrow blades. Provides the same thrust as a standard sailor prop with less drag when sailing. Also the Kiwi. It is a feathering design with composite blades. Less expensive than the all metal feathering designs, it is getting good reviews. see them both at www.westbynorth.com (no affiliation)
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