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Bonobo

Flexofold

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I have a Flexofold 2 blade prop that plays up. Reverse is fine. In forward the prop will not unfold. The way I get it out is to select reverse then forward. As long as the boat has no forward speed that works. Once out the propellor goes fine in cruise.

Another manifestation of the problem is when approaching marina or a mooring and power is reduced to idle forward. When RPM is increased prop has folded and will unfold. Only way is as above ie use reverse to bring boat to stop (or backwards) and select forward gear. Clutch etc have been checked. Any suggestions please

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when is the last time you physically inspected the actual prop ?

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Yes, I'd check the gears for barnacles, worms and other crusty bits.

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I had a two blade on the saildrive that did not have the anodes and the gear teeth got very corroded away, along with the blades. prop worked fine but would jam when the blades were moved by hand.  $1200 later and the prop is all good with anodes this time. 

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It seems that you are not the only one to have problems with the 2 blade flexofold. Did it used to work?

 

 

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Wow. I had one on my wish list, after reading the performance reviews. Cancel that. I will stay with my SS Slipstream. Geared two bladed, made in Ozz. Swapped props with the boat I sold. Good bye Kiwi prop. Have a Yanmar 2GM20 that makes 16hp. Motor was dancing around too much. Bought expensive made in Ozz motor mounts, and picked up over 1/2 knot. We can hit 7.1 in the Viking 33 in flat water, but usually motor at 5.75. That of course goes up and down on account of the tides and currents around here.

I check the prop every year, and clean and grease as needed.

Unkle Krusty

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1 hour ago, Unkle Crusty said:

Wow. I had one on my wish list, after reading the performance reviews. Cancel that. I will stay with my SS Slipstream. Geared two bladed, made in Ozz. Swapped props with the boat I sold. Good bye Kiwi prop. Have a Yanmar 2GM20 that makes 16hp. Motor was dancing around too much. Bought expensive made in Ozz motor mounts, and picked up over 1/2 knot. We can hit 7.1 in the Viking 33 in flat water, but usually motor at 5.75. That of course goes up and down on account of the tides and currents around here.

I check the prop every year, and clean and grease as needed.

Unkle Krusty

read again. The FoF that got good review is a 3-bladed. No problems with those - of course you have to have an anode.

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2 hours ago, Jaramaz said:

read again. The FoF that got good review is a 3-bladed. No problems with those - of course you have to have an anode.

I reread post number one and he says; I have a Flexofold 2 bladed prop. I said I have a Slipstream 2 bladed prop. So I thought I was on the same page. I referred to tests I had read. WoobaGooba has posted the link. Thank you WG. So far so good. The link then backs up what I hinted at. The Flexofold got a good rating for the 2 bladed folding prop. That is what got my attention and why I put it on my wish list. The test also says the 3 bladed feathering Kiwi prop is slow, in the order of .5 to .6 of a knot slower, than the best 2 bladed folding props. And bugger me, that is what I reported. To be clear, I attribute 1/2 knot to the mounts, and 1/2 knot from the Kiwi to  the Slipstream. It was after these two changes, and the increase in speed, that I took the Flexofold off the wish list, as it was not needed. 2 things I did not mention. The Slipstream is not great in reverse. At times I have to go WOT. The posted tests also state this fact.  But I view this as a small sacrifice on account of the minimum drag, and good forward speed. If the Kiwi prop hits a log, it can spin off in a nano second, never to be seen again. Friend with a Catalina 38 had that happen. He installed a 2 bladed folding prop.

I used two anodes on the shaft, checked and usually replaced every year.

We did 1000 nautical miles last summer going around Vancouver Island. Much of it motoring, a lot of it against the wind and tide, and thru some passages where the current runs faster than our boat speed. Obviously we have to time those. The R2AK guys have to do it without engine power. Bless them.

Unkle Krusty

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If its a geared folder or just a flapper the problem is usually the same, crusty build up of some sort. It doesnt take much to inhibit the blades from being thrown out and the only real solution is to remove the prop, dismantle and thoroughly clean the gears/sliding faces. In the meantime the short term solution is to rev it out in reverse and then into forward.

 

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Why would stiffer (or softer) engine mounts affect the amount of thrust the prop delivers?

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wonder if there is any chance the OP will come back and report ?

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So far so good! We have the new FoF composite folding 2 blade with anodes galore and it’s like a different, better world of motoring- backs up without Prop steer, stops a lot quicker and reliably, and best of all, we can cruise at 6 knots (square root of our WL) (2100 rpm) with 600 less rpm’s, which is really quiet.

Of course this is compared to the Martec 2 blade we had before.  Not having to sacrifice the usual chicken before engaging reverse is helping the sailing budget.  :)

Less messy too!

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9 hours ago, Zonker said:

Why would stiffer (or softer) engine mounts affect the amount of thrust the prop delivers?

With the old warn out Yanmar mounts, energy was being wasted with the engine dancing around. What concerned me most was the rubber hose piece that holds the stuffing box. It was moving too much. At least that is the theory I came up with. We go faster with the new mounts that we did with the old. The new mounts contain the engine much better. Specifically designed for the wimpy 2GM20. The heavier and larger capacity 2QM15 has more grunt. The newer engine just revs higher for a bit, 2, more horsepower.

Unkle Krusty

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On 2/24/2018 at 1:03 AM, Bonobo said:

I have a Flexofold 2 blade prop that plays up. Reverse is fine. In forward the prop will not unfold. The way I get it out is to select reverse then forward. As long as the boat has no forward speed that works. Once out the propellor goes fine in cruise.

Another manifestation of the problem is when approaching marina or a mooring and power is reduced to idle forward. When RPM is increased prop has folded and will unfold. Only way is as above ie use reverse to bring boat to stop (or backwards) and select forward gear. Clutch etc have been checked. Any suggestions please

I had a Flexofold 2 blade on my previous boat.  It worked as you describe, to open I put in reverse briefly then forward.  I thought that was normal.  It worked that way for years and I checked/cleaned it when I hauled every season, never an issue, gears moved smoothly, etc..  If you look at how the blades fit together when folded it's clear why it opens one way and not the other (it's hard to describe). 

I think I could spin it open in forward if I tried, but it took some RPMs and made a loud "clunk", so I didn't do it that way.

However, once opened mine never folded from just reducing the throttle.  I had to go all the way to neutral to get it to fold.  I thought it was a great prop, no complaints.

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Sometimes they wear and the folded blades are too close to unfold easily, depending on the design you probably need about 10 to 15 mm clearance

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I've never had a single problem with either of mine, one is a shaft-mounted race and the other is a saildrive mounted race. They are both flawless after 4 years.

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5 hours ago, Amati said:

So far so good! We have the new FoF composite folding 2 blade with anodes galore and it’s like a different, better world of motoring- backs up without Prop steer, stops a lot quicker and reliably, and best of all, we can cruise at 6 knots (square root of our WL) (2100 rpm) with 600 less rpm’s, which is really quiet...

Exactly this ^. I had one on my Yanmar sail drive. Never had a problem and  was easily the best prop out of the three I tried on the boat, including the fixed prop that came with the boat when I bought it.... As Zonker says, check for barnacles etc and wear and tear.or damage.

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I’ve had mine for 7 years and it has always worked flawlessly. I have to put the gearbox in reverse to get it to fold completely. As I understand, they are self cleaning, that the gears will crunch any fouling and keep itself clean. Of course, we sail our boat a lot so it has never been an issue. 

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On 2/25/2018 at 2:45 PM, MaxDog said:

I had a Flexofold 2 blade on my previous boat.  It worked as you describe, to open I put in reverse briefly then forward.  I thought that was normal.  It worked that way for years and I checked/cleaned it when I hauled every season, never an issue, gears moved smoothly, etc..  If you look at how the blades fit together when folded it's clear why it opens one way and not the other (it's hard to describe). 

I think I could spin it open in forward if I tried, but it took some RPMs and made a loud "clunk", so I didn't do it that way.

However, once opened mine never folded from just reducing the throttle.  I had to go all the way to neutral to get it to fold.  I thought it was a great prop, no complaints.

I have had three blade FOFs on our catamaran for six months, or mostly working on boat. Stbd. prop hesitant to open in FWD; Port works just fine. I will try the "reverse first" technique to avoid the clunk. I wonder if there is some calibration issue?

Thank you

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24 minutes ago, Never was said:

I have had three blade FOFs on our catamaran for six months, or mostly working on boat. Stbd. prop hesitant to open in FWD; Port works just fine. I will try the "reverse first" technique to avoid the clunk. I wonder if there is some calibration issue?

Thank you

On a 3-bladed FoF with opening difficulties I would recommend to check by hand of the prop blades are moving smoothly. If not (which is the most likely origin for not opening) then

1) Pivot pins - are they correctly mounted? Has anybody been putting them into place with a hammer? Remove and check that all three are moving smoothly in their holes and that both blades and pivot pins can be mounted with just a gentle pressure (add some nice water resistant grease when mounting). As I dismount my prop every fall then I clean the pivot pins carefully, if necessary sand with a very fine paper. The holes in the blades and hub gets the same treatment. Mount in the spring with some water resistant grease, most often the Volvo thing (as I use that to other operations as well, but any good will do).

2) the screws holding the pivot pins should have some locking liquid (locktite something, of medium strength). If too generous with this liquid it may have come into the blade mechanism. 

3) there is a cap that goes on the prop hub. It must be correctly mounted ... otherwise the center of the blades will touch this cap.

4) the cap is held in place by 3 screws which should have some of the same locking liquid, and if that ...

5) then there is the FoF specific anode, mounted with a screw. Original screw should be used, length etc is crucial. Again, there is some locking liquid ...

FoF.thumb.jpg.50f4c658d72ae9060eecf6e8006a0d4c.jpg

 

Most obvious is of course something, as some plastic or seaweed, has got into the mechanism. THat should be easy to see and fix, shouldn't need to dismount the prop. 

The anode in the pic has been used 2-3 seasons (each spring it is sanded to be even and offer some fresh zink surface). Now it is time for it to retire.

//J

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Had a 2 blade FoF on a J/109 on the Ches Bay for 4 years.  Loved it!  Would highly recommend...

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On ‎2‎/‎25‎/‎2018 at 10:58 AM, Unkle Crusty said:

With the old warn out Yanmar mounts, energy was being wasted with the engine dancing around. What concerned me most was the rubber hose piece that holds the stuffing box. It was moving too much. At least that is the theory I came up with. We go faster with the new mounts that we did with the old. The new mounts contain the engine much better. Specifically designed for the wimpy 2GM20. The heavier and larger capacity 2QM15 has more grunt. The newer engine just revs higher for a bit, 2, more horsepower.

Unkle Krusty

Did you go with new Yanmar mounts or did you use a different brand? I'm thinking of doing the same thing and looks like there's a few other manufacture options that look like better quality and less expensive.  

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53 minutes ago, sailingbeme said:

Did you go with new Yanmar mounts or did you use a different brand? I'm thinking of doing the same thing and looks like there's a few other manufacture options that look like better quality and less expensive.  

My opinion of the Yanmar mounts was never good. I used Isoflex mounts made in Ozz. Not cheap at around $240- each. Made in Spain Sole mounts were about $$70- each.  The 2GM20 is much happier. Now I want a bit more horsepower so I can motor at lower revs. I have all the contact info for Isoflex if you want it.

Unkle Krusty

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On ‎2‎/‎27‎/‎2018 at 3:52 PM, Unkle Crusty said:

My opinion of the Yanmar mounts was never good. I used Isoflex mounts made in Ozz. Not cheap at around $240- each. Made in Spain Sole mounts were about $$70- each.  The 2GM20 is much happier. Now I want a bit more horsepower so I can motor at lower revs. I have all the contact info for Isoflex if you want it.

Unkle Krusty

Thank you Crusty.....Haven't seen those brands here in USA but I will google them. I think it's PYI that promotes there brand as Yanmar replacements pretty well here. Another question, I think I've seen where Yanmar recommends heavier load mounts on the back to the engine or on one of the sides of the engine to take the torque. Did you do that or consider that also?   I have the 1gm so it really jumps around, especially at idle.  

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If you've extra stuff mounted on the engine: fridge compressor, 2nd alternator, etc, heavier mounts may be a good idea at the front.

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On 2/25/2018 at 6:07 PM, Training Wheels said:

I’ve had mine for 7 years and it has always worked flawlessly. I have to put the gearbox in reverse to get it to fold completely. As I understand, they are self cleaning, that the gears will crunch any fouling and keep itself clean. Of course, we sail our boat a lot so it has never been an issue. 

Can you see the prop so you know it has folded completely?  

Window?

 

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Normally don’t check,  as I’ve never considered it an issue. I should be able to see it; I’ll check next time out. I dive on it regularly, and it moves freely. Not uncommon for it to be folded when I dive on it, perhaps current or having it in reverse?

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