Flexofold prop FELL OFF!!

[fstbttms]

Originally Posted by JPA Cate

When you install the new prop, do it on the hard. It will be easier to tell if it is properly bedded to the shaft.

Ridiculous.

[SwellGuy]

Originally Posted by fstbttms

Ridiculous.

So you are saying it’s preferable to install a prop underwater? With a mask and other gear on? With limited visibility and where something as simple as a dropped or forgotten tool is an ordeal?

I guess if I made my living underwater I’d say the same thing, but I’d be lying!

[fstbttms]

Originally Posted by SwellGuy

So you are saying it’s preferable to install a prop underwater? With a mask and other gear on? With limited visibility and where something as simple as a dropped or forgotten tool is an ordeal?

I guess if I made my living underwater I’d say the same thing, but I’d be lying!

Did I say it's preferable to install underwater? No, I did not. But there is also no compelling reason to haul a boat to remove or install a prop. Especially when the work is done by an experienced professional. Any inference that an in-water installation is inherently inferior to an installation done on the hard is an inference made in ignorance.

But hey, it's your dime.

[Wotname]

Originally Posted by fstbttms

Did I say it's preferable to install underwater? No, I did not. But there is also no compelling reason to haul a boat to remove or install a prop. Especially when the work is done by an experienced professional. Any inference that an in-water installation is inherently inferior to an installation done on the hard is an inference made in ignorance.

But hey, it's your dime.

OK, I'm curious.

If fitting a new prop to an existing shaft underwater, how do you ensure the taper is fully contacting both surfaces?

If you can determine if the taper isn't fully bedded, do you lap the prop in a similar manner as when on the hard?

I'm not saying it can't be done but I would like to know how the experienced pros do it.

Put another way, help me to be less ignorant!

[a64pilot]

You can’t. You can’t be sure without machinist blue or similar and a fine paste.
I guess that could be done underwater if you could ding something to mark the shaft with underwater, but it’d got to get into the grain of the metal like machinist blue, it can’t sit on top like china marker.

Loctite thread lockers are in fact an adhesive, glue if you will. What differentiates them from most is that they are anerobic, that is they don’t set up in the presence of air, they set up when air is absent, so don’t squeeze the air out of a bottle thinking you’ll make it last longer, you’ll make it set up.
Eastman 910 (superglue) will work pretty well as a threadlocker if nothing else is available.

I’ve never heard of an underwater loctite does someone have a color or number of the underwater stuff?

[fstbttms]

Originally Posted by Wotname

OK, I'm curious.

If fitting a new prop to an existing shaft underwater, how do you ensure the taper is fully contacting both surfaces?

If you can determine if the taper isn't fully bedded, do you lap the prop in a similar manner as when on the hard?

I'm not saying it can't be done but I would like to know how the experienced pros do it.

Put another way, help me to be less ignorant!

Nobody laps the prop. Not the manufacturers when boat is commissioned, not the yards when they replace a prop and of course no diver is lapping a prop. And that covers 99.9% of all props installed on any pleasure craft. It simply is not standard procedure. And people aren't losing props because of it.

[a64pilot]

Well, I lapped mine. Used machinist blue and valve grinding compound.
But then a lot of people don’t use a torque wrench on things that should be torqued too, and wheels don’t seem to be falling off of cars either.

[Training Wheels]

I lapped mine!

[DefinitelyMe]

I could be remembering this wrong..... please do correct me if I'm spouting nonsense, but:

I installed our flexofold underwater about 4 years ago and I do vaguely remember having concerns about the main nut that holds the thing on the shaft. As I recall I had to spin the nut on, stick a deep socket on it then install one of the blades and jam a bit of wood between it and the hull. Tighten the nut, then remove the blade, extract the socket and finish the assembly. I vaguely remember thinking that there was sufficient space behind the main nut before it hits the covering plate that it could potentially have come un-screwed, causing the prop to drop off. This must, logically, have been what happened to you. Is there a retaining set-screw? I don't remember........ But even if there is it will not work too well in the event that the nut wasn't positioned correctly when it was set (i.e. on a flat section).

Whichever way you cut it, if your prop came off then that nut came un-done. Unfortunately I fear you may never know why since regrettably you weren't the one to do the installation.

As far as getting a new prop goes, all I can say is that I'm very sorry this has happened to you. We love our flexofold and are pretty confident at this stage that it won't fall off!

[kenbo]

Originally Posted by fstbttms

Nobody laps the prop. Not the manufacturers when boat is commissioned, not the yards when they replace a prop and of course no diver is lapping a prop. And that covers 99.9% of all props installed on any pleasure craft. It simply is not standard procedure. And people aren't losing props because of it.

OK, nobody laps and tests for adequate contact, maybe that's why the marine trades have such a bad reputation today.

But please help me understand how you fit the key and how you insure it doesn't stand proud in the keyway and bind the prop.

I've watched one of your videos a few years ago and when I saw you using a pipe wrench to remove prop nuts I had a good laugh.

[fstbttms]

Originally Posted by kenbo

But please help me understand how you fit the key and how you insure it doesn't stand proud in the keyway and bind the prop.

You do it by fitting the prop without the key and then fitting the prop with the key. If if the prop does not fit the same with the key in place, you get to spend some quality time with the key and a file. It ain't exactly rocket science.

Originally Posted by kenbo

I've watched one of your videos a few years ago and when I saw you using a pipe wrench to remove prop nuts I had a good laugh.

When you've installed as many props underwater as I have over the course of 25 years, then I'll give a sh*t about what you think of the tools I use to do it.

[kenbo]

Originally Posted by fstbttms

You do it by fitting the prop without the key and then fitting the prop with the key. If if the prop does not fit the same with the key in place, you get to spend some quality time with the key and a file. It ain't exactly rocket science.



When you've installed as many props underwater as I have over the course of 25 years, then I'll give a sh*t about your opinion of the tools I use to do it.

Sir, with respect, as Plato would say, you are double ignorant.

[CarlF]

I once had a Gori prop fall off (and heard of others experience the same thing). But never heard of a FF falling off. The FF has a shaft nut locking screw that makes it very unlikely to come off if installed according to instructions.

For my Gori, it evidently was due to an improperly sized key (the PO had installed it and used the same key as had been on the previous different brand prop rather than making a new key). Evidently, the too wrong shaped key allowed the prop to wiggle a bit on the shaft which backed the nut off very slowly.

I replaced with a Flexofold and new key and it has never come loose despite having been taken off a few times (always out of the water).

So I would first suspect the key. Was it carefully fit to the prop and shaft?

2nd would be the taper was wrong. Mine wasn't lapped but it was carefully checked that it seated well and didn't rock on the shaft (easier to do out of the water)

Next is the 70Nm of torque needed on the prop nut. Not easy for a diver to apply that much torque underwater - unless you have a really big wrench

And finally - and most likely - the shaft nut locking screw. This goes in with an Allen wrench and is easy to not notice or forget. It needs to be tourqued to 10Nm (which is also hard with an Allen wrench). And finally, the screw must be new with factory applied underwater thread locker. If the screw is ever removed, a new one must be used for underwater installation (on the hard you can re-use it with your own thread locker.

If this screw was not installed properly, it would take quite a while for the prop nut to loosen - but it would eventually. My Gori lasted from Annapolis to Nova Scotia and back before it fell off.

[fstbttms]

Originally Posted by kenbo

Sir, with respect, as Plato would say, you are double ignorant.

Spent a lot of time underwater installing propellers, have you? Bwahahahaha!

[hugosalt]

Addressing post # 2 ....FOF props falling off a number of saildrive charters...

In 2007 had yard install my FOF on saildrive as I did not want to install myself and risk losing prop...at haul out after long season prop was very close to falling off. I reinstalled myself, after reading instructions, this time using the(what I call) "tab washer" that was still in the box. Believe (memory?) it went between double nuts and then the tab was bent down to lock in nuts. Could explain a lot of lost props, at least from Saildrives.
No problem since reinstall but as I used some red locktite, to be sure, I will be in for an adventure removing prop to change seals this year.
(heating to 300 odd degrees)

Also think??? that tab washer(should)be used to lock in nuts on shaft installs
as well but have no 1st hand knowledge.
Any experience/knowledge or manual will have.