My prop fell off... f.ck f.ck f.ck.

[Seaworthy Lass]

Originally Posted by beneteau-500

Hoppy just caught this thread. One thing for shore once you request a tow in Greece they will impound your yacht you must hand over all yacht papers etc supposedly the repair must be done by a qualified engineer and then certified by a loyds registered surveyor this happens to me ie blown head casket the cost to me by the surveyor was 1000 euros another British yacht broke prop shaft the next day after my failure and cost him the same amount

I warned Hoppy about this back in post #10. It seems to be a common practice here in Greece, even if the initial problem resulting in the request for a tow is quite trivial.

When we had engine failure several years ago and were returning to Greece for an engine replacement, the marina suggest we sail through the channel into the marina itself before they towed us to a wharf. We were puzzled at the time, but later very thankful we had not insisted a tow was required for any more than a few dozen metres.

In one instance following tow due to a rope around the prop (Aussie friends) the surveyor's hefty fee was apparently handed over without any inspection of the boat.

SWL

[hoppy]

It's amazing that with such creative fee collection scams that the country is bankrupt....

The flexofold is now cleaned and disassembled and as it seems complete. The shaft nut retainer screw was still in there, but deep so I could not see it earlier. I disassembled without touching the screw and found that it only just came out the hole where the nut is.

One thing I noticed is that the shaft was only half way through the nut based on the barnacle growth inside. I will be interested to see how it looks when I refit it.

I did see signs of loctite red on 3 screws but nothing on any other. The locking screw was easy to turn so maybe there was no loctite on it?




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[a64pilot]

If your locking screw screw works like mine and your boat is out of the water, it might be worth torquing everything down, indexing it so you can put it back together exactly the same way and using a drill bit to put a dimple in the prop nut that the locking screw will fit into.
I used blue loctite as the red is stud and bearing mount, says on the bottle that it may take excessive force and or heat to remove it, I don't use red on anything I want to take apart, think of it like 5200.

[Wotname]

Originally Posted by hoppy

One thing I noticed is that the shaft was only half way through the nut based on the barnacle growth inside. I will be interested to see how it looks when I refit it.
Attachment 108005


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I'm not familiar with the flexofold prop but I believe you should really ensure that your tapers fit absolutely properly. Use Prussian blue or similar to get better than 90% fit. If less then lap with grinding paste.

Lack of perfect fit maybe why you lost it in the first place,

[sanibel sailor]

I suspect mating prop and shaft is rarely done in practice and yet every prop I can remember pulling was quite firmly attached, requiring a puller of one sort or another. I am not familiar with the details of this prop, but suspect something other than a few thousandths of mismatch was the cause.

[DeepFrz]

Originally Posted by sanibel sailor

I suspect mating prop and shaft is rarely done in practice and yet every prop I can remember pulling was quite firmly attached, requiring a puller of one sort or another. I am not familiar with the details of this prop, but suspect something other than a few thousandths of mismatch was the cause.

And yet this is not an uncommon problem. Surprising number of instances, to me at least, while docked or at anchor.

[model 10]

Originally Posted by DeepFrz

And yet this is not an uncommon problem. Surprising number of instances, to me at least, while docked or at anchor.

Bronze is pretty soft. A miss match in the taper between steel shaft and the bronze prop hub could cause looseness.

[sanibel sailor]

Originally Posted by Guy

Bronze is pretty soft. A miss match in the taper between steel shaft and the bronze prop hub could cause looseness.

Wouldn't that softness make it conform and adapt to mismatch?

[model 10]

Originally Posted by sanibel sailor

Wouldn't that softness make it conform and adapt to mismatch?

If you continue to re torque every 50 hours until that happened.

[Wotname]

Dont forget that seawater does get into all areas of mismatch, causing corrosion, possible binding and possible loosening.

Maybe many don't care and rely on the cotter pin, the key, the locknut or whatever but a tight taper is best practice bar none.

[Cheechako]

I've never had a taper not fit well. It's pretty easy to check, just finger tighten the prop nut and try to rock it on the shaft. If you are getting no apparent losseness then it will not be there once you torque the nuts for sure.


It's kind of surprising actually, as it takes very little variation in angle to make a taper not fit well engineering wise.
Some of my keys have been bronze or brass , not sure which they were. They were a tight fit in the keyway... often requiring a light tap to get in the keyway.

[Training Wheels]

When we bought our boat, it had a Martec folding prop. During the haul and survey, the boatyard pulled the prop to change the cutless bearing. A few months later, we backed out of our slip hard, as there was a bit of leftover surge from a tsunami in the harbor. Put it in forward, nothing happened. Prop spun off. The boatyard said "of course we installed the prop properly, you must have done something to it."




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[model 10]

Originally Posted by Wotname

Dont forget that seawater does get into all areas of mismatch, causing corrosion, possible binding and possible loosening.
one.

The reason they used white lead on submarine prop hubs.

[Wotname]

Originally Posted by Cheechako

I've never had a taper not fit well. It's pretty easy to check, just finger tighten the prop nut and try to rock it on the shaft. If you are getting no apparent losseness then it will not be there once you torque the nuts for sure.


It's kind of surprising actually, as it takes very little variation in angle to make a taper not fit well engineering wise.
Some of my keys have been bronze or brass , not sure which they were. They were a tight fit in the keyway... often requiring a light tap to get in the keyway.

While this a reasonable check for looseness, it does not tell you anything about the total bearing surface of the taper. Keep in mind that the torque is meant to taken by the bearing surface rather than the keyway, you want as much bearing surface as possible.

It is one of the easier things to check and fix in the total drive train.

[hoppy]

The Flexofold is back on



It seems that only half the thread of the lock nut is ever used. So the growth I saw was to be expected.



I fitted the replacement screw kit which already had loctite on it. The prop nut locking screw did not have any loctite on it. I fitted all as per instructed rather than trying to "improve" it. It lasted 4.5 seasons that way. I will make it a standard haul out activity to disassemble and retighten the prop nut.

The haul out at Olympic Marina was nasty @ €742.... It was not nice to pay but it was better to do this than to have to install the flexofold under water or to even just try to fold over the washer on the fixed prop to secure it. I will sleep better at night without the money