Flexofold prop FELL OFF!!

[HeinSdL]

Flexofolds use a spline, nothing to lap

[fstbttms]

Originally Posted by HeinSdL

Flexofolds use a spline, nothing to lap

All saildrive props are splined. But Flex-O-Folds mounted on shafts are not. Like all shaft-mounted props.

[HeinSdL]

Originally Posted by fstbttms

All saildrive props are splined. But Flex-O-Folds mounted on shafts are not. Like all shaft-mounted props.

Aha! Now I get it. So the flexofold on a shaft is mounted on a taper. Probably the reason for losing these props in both applications are the same: incorrect application of the nut, locking bolt and deformable washer. I find it odd that flexofold don't incorporate some kind of locking screw coming in from the side definitively locking the nut.

When I lost mine I was just about to come to a gentle stop in a lock in The Netherlands and only realised it was gone when wanting to exit smartly after the gates opened. One feels rather impotent in such a moment.... since that time I manoeuvre assuming I have no reverse (I don't trust the flexofold) and that has greatly added to a sense of non urgency while making our way through marinas.

[Sailing4Jesus]

If you end up replacing it you should look into MAX-PROP as they are certainly the best, and a big plus with MAX-PROP is that you can do the installation yourself. Go to https://www.pyiinc.com/videos.html
There you can watch videos that show you how easy it is to install any MAX-PROP yourself. In addition, if you contact the MAX-PROP distributer in your area they will give you assistance in selecting which MAX-PROP will be best for your yacht.

Signed, Senior Chief, U.S.NAVY,RETIRED

[fstbttms]

Originally Posted by HeinSdL

Aha! Now I get it. So the flexofold on a shaft is mounted on a taper. Probably the reason for losing these props in both applications are the same: incorrect application of the nut, locking bolt and deformable washer. I find it odd that flexofold don't incorporate some kind of locking screw coming in from the side definitively locking the nut.

Just for clarity’s sake- shaft-mounted Flex-O-Fold props do not incorporate the tab washer.

[MartinR]

Just fishing a little bit. Both the shaft and the prop were metric?

Props fall off due to incorrect installation. There are a few ways to get this wrong.

[stormalong]

You said that you lost the prop when going at low speed exiting a harbor. If you know pretty close where it is and the bottom is not mud it may be a good investment to get a local diver to try and find it.

As already said a properly fit prop does not just come off. I have had to heat my Maxprop hub and put a lot of tension on it with a puller to get it off. If the taper was right I'll bet it was never torqued properly - a difficult thing to do in the water.

[jmschmidt]

Why have an expensive folding or feathering prop on a charter boat? So the charter customer can get to the next shore-side bar five minutes faster?

You also mentioned another good reason to outlaw sail-drives, the worst invention of the maritime industry.

[bcboomer]

Originally Posted by sailorboy1

The taper fit isn’t what transmits the torque, it’s the key. Just because a prop presses onto the shaft and you can’t remove it by hand is meaningless.

Actually the taper/interference fit does transmit the torque, just like on some vehicle axles.
I would guess the nut wasn't torqued properly.

[bcboomer]

Originally Posted by kenbo

True but there are a lot of folks driving cars with pulsating brakes because the disc is warped by uneven lug bolt torque.

Exactly true. And how many "professional" mechanics use a torque wrench instead of one of those useless torque sticks on an impact?

[sailorboy1]

Originally Posted by bcboomer

Actually the taper/interference fit does transmit the torque, just like on some vehicle axles.
I would guess the nut wasn't torqued properly.

Tell you what, lap the heck out of yours till the fit is perfect and then install the prop without the key and see how it goes.

Btw- if you are talking like the front wheel of a car I guess you don't understand difference between something rolling on a tapered bearing compared to a torque load

But I'm not going to debate it anymore

[billgewater]

I am no expert as I have only ever had a fixed blade prop on a standard shaft drive, but looking at the diagram it seems to me that there should be some mechanical method (e.g. a crown nut or a wire fed through lock etc.) Reliance on any chemical such as loctite etc seems a bit adventurous considering the violent shuddering a prop experiences.
If such a system fails then there would probably be no warning rumbling whereas a mechanical lock may provide a bit of warning as the boss loosens off the shaft. Considering the extreme importance of the reliability of a prop attachment you would think that a fool proof attachment method would be used.
Have a look at your rigging. Split pins and lock nuts re regarded as essential and are generally fool proof. Anchor chain shackles use twisted wire locks. Many big end engine bearings use folded metal locks on the thru bolts. Same approach should be used with props.

[Jim Cate]

“Factually incorrect”? OK, now you’re just parsing my words.

No, Fastb, he is refuting your exact words "Nobody laps the prop." Some folks do indeed go through this process.

And if the OP is to be believed, the prop was not lapped, it was installed in the water by a pro diver, and it fell off later. No causality can be determined from this set of facts, but SOMETHING in the process failed to work properly.

I'm not arrogant enough to suggest why when I wasn't there to see how it was done.

Jim

[David B]

Originally Posted by Lifeonalean

Well I was motoring slowly out of the harbor when all of a sudden I had no propulsion. Was lucky enough to coast to an anchorage and drop anchor. Dove the boat and found the shaft to be completely bare! My issue is, I really liked the flexofold and now I wonder is there a design flaw? Bad installation? Attempted theft maybe? I feel like the installation must have been done right because we just sailed from Seattle to Newport Beach California right after install and motored probably half the way. I would think this would’ve happened sooner? Has anyone ever heard of this with a flexofold? Doesn’t seem possible to lose all of it at once considering how it is put together. Opinions? Advise?

Respectfully, I suggest it was not installed properly. There is no way there is a fault with the design. Have a look at this video I made, putting ours back on. I emphasise the way everything is retained - everything!

The Loctite is only used for retaining the anode(s). All other nuts and screws are liberally coated with grease when I install (ours has been on for 8 years now - love it!).

I suspect the locking tab that secures the locking nut that secures the mounting nut, was either not installed, or not fitted correctly, with the sides bent into position. When fitted underwater, the factory-supplied socket-head retaining screws come pre-coated, but again, those are only for the anode(s).

I intend doing more 'Boat Tech' vids on our channel, as that one seemed to be popular . Hope this one helps in the meantime.

https://www.youtube.com/watch?v=fCon...Fkem2rAfGTbcuK

[Mistress Sirena]

Originally Posted by Training Wheels

I lapped mine!

I confess Never lapped :many props mostly power...