On my 37H I installed an old Michigan folding prop. my teeth nearly fall out when starting until it snaps into place with a hell of a clunk. Same reversing with an unnerving time lag when maneuvering. I did check and it runs freely. I'm thinking of trying to find a used three blade with the geared action. A big concern here in Maine is all the darn lobster traps so I prefer folding over feathering. Anybody have any experience on this or suggestions?
Folding Prop?
- Thread starter DanMaine
- Start date
I am not familiar with the Michigan folding prop but it sounds like it might be worn out. Specifically, the hinges on which the blades fold may be worn and no longer functioning properly. I have a Martec folding prop which also has two independently folding blades (not geared) and I know that it needs to be sent back to Martec every few years to get refurbished for that very reason. They also warn against buying used ones as that is often an issue. The geared folding props work great but are very expensive.
We have 5 years and about 350 engine hours on our flex-o-fold 3 blade. No issues at all. No clunking, and no required maintenance except the usual anode replacement.
+1 for Flex-o-Fold here. Two seasons and just a good pressure wash, anode replacement, scuff and repaint the blades with galvanized paint. No maintenance recommended.
We have 5 years and about 350 engine hours on our flex-o-fold 3 blade. No issues at all. No clunking, and no required maintenance except the usual anode replacement.
Well i guess I will replace mine! No clunks nor vibration issues then? any size recommendations? Anyone have a used one they might part with?
I called Flex-O-Fold with my engine size, displacement, and transmission gear ratio. They gave a recommendation and it worked out fine. I can still reach maximum RPMs and motoring speed is just slightly higher than the OEM fixed prop.
Davidsailor26 has it right - with Flex-o-fold you contact them with engine (e.g. Yanmar 3YM30), transmission and ratio (e.g. Kanzaki KM2P-1 with 2.6:1) and shaft size, and they'll tell you what size two blade or three blade is appropriate. They're very responsive. I had a prop shop install mine professionally and change out the cutlass bearing at the same time (fairly sure it was the original from 2009). Its a thing of beauty when you first open the box. One of the best improvements to the boat that I made. Went with the 3-blade as I'd read some reports about two blade Flex-o-Fold having noticeable vibration. My 3-blade does not. If you haven't read this thread with Mainesail's detailed thoughts, DO SO ASAP, its a great one:
Folding Prop Report | Sailboat Owners Forums
After reading that thread, it sounds just like my vibration problem, too much weight aft with my present folding prop. But I'm hearing good reports. I'm confused. I have a thin 1" shaft. maybe it's longer than the others which would make it vibrate easier.
Thumbs up for flex-o-fold. Amazing piece of technology. I've installed one on each of two very different boats and the guys in Boston absolutely nailed the specs both times.
I've heard great things about the Flex-O-Fold and am about to buy a 3 blade. Does anyone with a Flex-O-Fold know their diameter and pitch ? Unlike the Maxi-Prop(feathering), there is no pitch adjustment. I'm leaning to a 17x11. Details of my thinking follow:
I have a Yanmar 3GM30F on my cutter 37 that they rate at 27 HP at 3600 rpm for 1 hour or 24 hp at 3400 rpm continuous. I run the motor at 2800 rpm general cruising or 3000 rpm for a delivery. Flex-O-Fold initially suggested a 16x11 prop using the 3600 (unrealistic) rpm number. In asking FOF to double check this, it showed they entered the boat weight incorrectly. They next ran the prop calculator for 3000 rpm with the corrected boat displacement at 24 hp to come up with a 16x13 prop. For some reason a 17" prop was not suggested.
Like many on this and other threads I went to a 3 blade fixed after I found a 2 blade prop had low acceleration. When motoring into a sea, a large wave took 3 or more knots off the speed. A 2 blade prop could not accelerate before the next wave hit which killed all headway. A 3 blade in this situation worked fine. I did not have vibration issues with a 2 blade as others have reported.
There is room for a 17" prop on the Hunter/Cherubini cutter 37. I'd guess that like the difference between a 2 blade and a 3 blade, the 17" has better acceleration (bite) than the 16". The larger blade area doesn't matter sailing as it folds. I understand the science says a 17" prop is slightly less efficient than a 16" prop
I have a Yanmar 3GM30F on my cutter 37 that they rate at 27 HP at 3600 rpm for 1 hour or 24 hp at 3400 rpm continuous. I run the motor at 2800 rpm general cruising or 3000 rpm for a delivery. Flex-O-Fold initially suggested a 16x11 prop using the 3600 (unrealistic) rpm number. In asking FOF to double check this, it showed they entered the boat weight incorrectly. They next ran the prop calculator for 3000 rpm with the corrected boat displacement at 24 hp to come up with a 16x13 prop. For some reason a 17" prop was not suggested.
Like many on this and other threads I went to a 3 blade fixed after I found a 2 blade prop had low acceleration. When motoring into a sea, a large wave took 3 or more knots off the speed. A 2 blade prop could not accelerate before the next wave hit which killed all headway. A 3 blade in this situation worked fine. I did not have vibration issues with a 2 blade as others have reported.
There is room for a 17" prop on the Hunter/Cherubini cutter 37. I'd guess that like the difference between a 2 blade and a 3 blade, the 17" has better acceleration (bite) than the 16". The larger blade area doesn't matter sailing as it folds. I understand the science says a 17" prop is slightly less efficient than a 16" prop
You REALLY need to contact Flex-o-fold directly on your particular boat. Getting advice here may or may not be good and it would be a very expensive non-returnable purchase. Flex-o-fold will ask you some specific questions about what motor and transmission you have, the size of your prop shaft, etc. They can then tell you exactly which of their 2 or 3 blade props are correct. They're very knowledgeable and responsive. They'd be able to give you advice on a 16" vs 17" prop for your boat, and why it might or might not be a good idea.
Good luck.
Good luck.
Contact Flex-O-Fold ?
I've done 6 back and forth emails with Flex-O-Fold. I don't want to have the wrong prop with an overloaded motor or a boat without speed at high rpm. My problem with Flex-O-Fold is they quoted a different prop than they quoted several years ago. The prop calc program print out they sent me showed errors. They didn't really know if they should be running a calc at 3600 rpm or 3000 rpm. I'm hoping to get the prop sizes of people with a Flex-O-Fold prop on a cutter 37 to solve this question.
I've done 6 back and forth emails with Flex-O-Fold. I don't want to have the wrong prop with an overloaded motor or a boat without speed at high rpm. My problem with Flex-O-Fold is they quoted a different prop than they quoted several years ago. The prop calc program print out they sent me showed errors. They didn't really know if they should be running a calc at 3600 rpm or 3000 rpm. I'm hoping to get the prop sizes of people with a Flex-O-Fold prop on a cutter 37 to solve this question.
I gave Flex-O-Fold my boat model (Beneteau 37), engine HP and max RPM (29/3600) and gear ratios (1:2.62 forward, 1:3.16 reverse). They recommended a 16x12-3R. That’s what I got and it’s worked well.
I suspect the max RPM is what matters for prop sizing, not the standard cruising RPM. You want the prop sized so that you can still achieve the max RPM at full fuel, not to lug the engine spinning slower and over propped. I cruise at 2800, but giving them my max rated RPM of 3600 got the calculations to the right point and my prop behaves correctly.
Have you tried using the blinkin' telephone and explain this to them? The reason why is given below.
I just had a very pleasant experience with a vendor who had sent me a quite helpful email in response to a product I'd returned to him. We got more done in one 10 minute phone call than we could have in 29 emails.
Why oh why can't people pick up the blinkin' phone anymore?
I do not have a specific answer but some observations. My daughter has a 1984 H37C with a 3qm30 Yanmar. Rated at 30hp and max rpm 3000. With her Campbell Sailer 3 blade prop she cruises at 6.3 kts. WOT 7 kts. Theoretical hull speed 7.3 kts. I do not know the diameter or pitch of the Campbell prop but Yachting Monthly September 2009 rated it the least drag of anyfixed three blade prop. My son has a H410 with a 54 hp yanmar also with a three blade Campbell sailer and he cruises at 7.8 kts at 2800 rpm. The point is if you want an alternative to the more expensive FOF consider the Campbell Sailer. On my boat, H466 with the 76 hp 3600 rpm Yanmar I switched from my fixed three blade 18 x 17 to a 20 x 14 three blade FOF. They had originally recommended a 22 x 14 but I was concerned with tip clearance and went with the 20 x 14, which coincidentally a buddy of mine with the identical boat had so another reason to go with the 20 x 14. I did call the plant in Denmark and had a very pleasant conversation with them.at 2900 rpm 8kts. For the Campbell Sailer see info@westbynorth.com or 778-802-4202. They are located in British Columbia and have a wealth of information and are also very easy to speak with.