I'm considering replacing a traditional 3-blade fixed prop with a two-blade folding prop. I like the idea of a folding prop for sailing, but am wondering if there's much loss of speed or power when motoring. Thoughts? Thanks.
Folding props
- Thread starter steve_in_Lex
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We are considering doing the opposite. Our recently purchased boat has a folding prop on it, and we are not confident that it was sized correctly. The boat has a 2GM20 Yanmar that can hit 3800+ RPMs when the throttle is pushed forward to the limit. That is not the best situation.
Furthermore, the folding prop does not let this boat back very well. I'm sure some of the fault lies with my inexperience with the boat as I have mentioned in other posts. Last week the boat backed pretty well instead of walking to port as it had done the first time I tried to back into our slip. This time the maneuver was done at low tide and the keel dragging in the mud helped negate the prop walk, I think.
About 12 years ago we had a folding prop on an Irwin 31. That prop performed very well in all respects.
I believe that the correctly sized folding prop would be OK for a lighter boat, but the size and displacement of a Pearson 35 might not be handled very well. My opinion, not based on very wide experience with folding props. One gets (+) and one gets (--).
Best wishes, Phil
Furthermore, the folding prop does not let this boat back very well. I'm sure some of the fault lies with my inexperience with the boat as I have mentioned in other posts. Last week the boat backed pretty well instead of walking to port as it had done the first time I tried to back into our slip. This time the maneuver was done at low tide and the keel dragging in the mud helped negate the prop walk, I think.
About 12 years ago we had a folding prop on an Irwin 31. That prop performed very well in all respects.
I believe that the correctly sized folding prop would be OK for a lighter boat, but the size and displacement of a Pearson 35 might not be handled very well. My opinion, not based on very wide experience with folding props. One gets (+) and one gets (--).
Best wishes, Phil
The real test for prop sizing is from a dead start pushing to full throttle and seeing if the engine takes on a serious load until the boat speed comes up the match the prop. I was way under propped and the engine would go to 3000 rpm while the boat was dead stopped then it would slowly accelerate.
I went from a fixed three blade to a three blade Flex-o-fold. I could not be happier. I don't think the drag reduction from a 3 blade folding to a 2 blade folding is really significant. I think the flex-o-fold USA rep works in Massachusetts.
I saw no difference in backing, I gained .2 kts under power, sailing is now as efficient as it can be w/re to underwater drag, and the transmission does not freewheel when sailing.
Count me satisfied.
I saw no difference in backing, I gained .2 kts under power, sailing is now as efficient as it can be w/re to underwater drag, and the transmission does not freewheel when sailing.
Count me satisfied.
I changed from a 16x11 fixed 2 blade to a Gori folder which I believe is 16 x 14 that I purchased used. I know it's over pitched for my 2GM20 Yanmar, and I max out at about 3200rpm. I mostly use the engine to get in and out of my mooring and about 10 minutes to get into Lake Michigan. I don't normally do extended cruises. The main reason for getting the folder was Yanmar's insistence that the engine not be locked in gear while sailing. I hated the rotational noise from the rotating fixed prop.
The advantages were that I gained almost a full knot in sailing speed, lost no overall speed in motoring, and got far better response in reverse. Most of my motoring is in no wake zones. As a result, I cannot run the engine in higher rpm ranges. I have considered contacting Gori to see if I could somehow get a pair of 11 pitch blades without having to apply for a mortgage.
The advantages were that I gained almost a full knot in sailing speed, lost no overall speed in motoring, and got far better response in reverse. Most of my motoring is in no wake zones. As a result, I cannot run the engine in higher rpm ranges. I have considered contacting Gori to see if I could somehow get a pair of 11 pitch blades without having to apply for a mortgage.
I took off our folding prop because I couldn't back up. I'm happy with a fixed prop. I don't worry about the 0.1 knot loss while sailing. I guess I'm a cruiser and being able to come to a dock and stop is a bigger deal to me. When the boat is on the hard that bronze folding prop is a lot sexier, but I prefer to be in the water.
Ken
Ken
There are folding props and there are feathering props. A quality feathering prop allows you to adjust blade pitch for optimum efficiency, and a 3, 4 or 5 blade feathering prop can increase your fuel efficiency and reduce vibration. My 3 blade max prop reverses pitch and provides far more power in reverse than the OEM fixed 3 blade. Any final decision on prop purchase should include review of the manufacturer's instruction on transmission selection during sailing. Many Yanmar installs require neutral, and you will be listening to shaft rumble as a result, unless you install a folder/feathering prop.
A cheaper alternative to a feathering / folding prop is the Campbell Sailer (http://www.westbynorth.com) Since it is a foil shaped blade it doesn't tend to cause the shaft to rotate much (or any I've heard), and has a low drag profile similar to that of a normal 2 blade, or maybe even less.
Maine Sail has reviewed them very positively as well, and I know at least one person who uses one to great success as well.
Plus if you race, you get the credit for having a 3 blade, but the drag profile of a 2 blade, so you may do a little better in races
Maine Sail has reviewed them very positively as well, and I know at least one person who uses one to great success as well.
Plus if you race, you get the credit for having a 3 blade, but the drag profile of a 2 blade, so you may do a little better in races
My boat came with a Maxi 3 blade feathering prop and it is fantastic. If money is not a problem I would go with this prop. Had it not been installed on the boat when i bought it, I would not have spent the money. The Maxi is the cat's meow. Great performance in both directions.
I have switched from fixed to folding on two boats and really don't notice much of a difference under power. As long as they are correctly sized. But your boat will sail noticeably faster. Mine have been older Martec ones that I ebayed.
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