Flexofold prop FELL OFF!!

[skipperpete]

There are many instances of keyless tapers , I have to deal with them from time to time and use a small hydraulic power pack to pop the hub off the taper (not a puller) .....a drilling through the hub accepts the hydraulic pressure. Larger ZF reversing gears use a combination puller and hub tap line....no key for more than 1,000 hp. BMW outdrives, same system, no key. More relevant to cruisers are the keyless Vetus couplings for plain ol parallel prop shafts... pinch type and also collet(taper) type.

[SailingHarmonie]

Originally Posted by sailorboy1

guess you guys never took mechanical design

but I don' care and am amazed you dug up such an old thread

Actually, I do mechanical design. You were wrong then, and still wrong now.

[Tin Tin]

For this to spin off, (probably in reverse), the hex "crater" screw that locks the shaft nut in place may have :
1. Not been inserted far enough at the right torque, may be cross threaded

2. The correct underwater curing Loctite was not used or was insufficient if original screw was used

3. The mating surfaces of the crater screw were not clean and grease free so loctite was ineffective
4. The hex screw point sheared off from maybe corrosion - was it a new screw from flexofold with the pre-applied loctite??


Whilst I am sure it is done often, to me looks like a fiddly thing to do underwater, too easy to screw up.

[bcboomer]

I'm no engineer but was told by an engineering team that the key is just to have the hub and shaft go together the same way every time.
That was for an application that was subject to way more torque than our props ever see.
Maybe the lower torque load is why so many boats get away with not lapping the joint and depend on the key.

[Wotname]

Engineers, machinists, mechanical designers and discerning readers will all know the taper transmits the torque. Anyone else can believe whatever alternative facts they care to.

[Big Moe]

I have put Flexofold props on my last three boats. I am currently running a three blade Flexofold on my 2009 Beneteau 49. If the prop came off your boat it was due to a faulty installation. The lock nut and key were not correctly installed. I haul every year and clean my blades with a glass bead machine. I always check my nut. It hasn’t loosened one iota since my original install.

Definitely a poor installlation.

[malbert73]

Originally Posted by Big Moe

I have put Flexofold props on my last three boats. I am currently running a three blade Flexofold on my 2009 Beneteau 49. If the prop came off your boat it was due to a faulty installation. The lock nut and key were not correctly installed. I haul every year and clean my blades with a glass bead machine. I always check my nut. It hasn’t loosened one iota since my original install.



Definitely a poor installlation.

Flexofold devotee here too since 2015. Never loosened one bit either for me.

Tell me about the glass bead tool. What’s that?
I’ve been using a random orbital sander with 150 grit to clean, and trying not to scoff the bronze too much - I wonder if that’s a bad idea…

[Big Moe]

https://www.eastwood.com/eastwood-b6...-cabinet.html?

I use glass beads and clean my prop in minutes!