Prop fell off

[raz88 97]

So today my prop fell off.

 

Dropped sails and came to motor into bay and no drive. Check linkages on shifter and saildrive and all ok. Re hoist sails and sail to anchor. Jump in water with mask and confirm missing prop diagnosis.

 

Now this prop I had "rebuilt" and professionally re installed, last year. I had it professionally installed so that it wouldn't fall off.

 

So what I'm now wondering, is whether I should have been checking it was still done up tight, or doing something to make sure it wasn't going to fall off? Or should I be ringing up the engineer that put it on and asking for some sort of compensation?

 

I was there when he put it on and he didn't seem to be the cutting corners type. And I've probably done 100 hours on it so it isn't like it fell off the week after it went on.

 

But at the very least I'd like to figure out how to make sure the next one doesn't fall off.

 

Any ideas?

[Chloe 7]

Locknut 

[wheels 544]

More details please. What prop is it? I assume by the word "rebuilt", it is a folding prop of some kind. There are several makes and each have their own way of being locked onto the Shaft.

[rmiker 15]

So today my prop fell off.

 

Dropped sails and came to motor into bay and no drive. Check linkages on shifter and saildrive and all ok. Re hoist sails and sail to anchor. Jump in water with mask and confirm missing prop diagnosis.

 

Now this prop I had "rebuilt" and professionally re installed, last year. I had it professionally installed so that it wouldn't fall off.

 

So what I'm now wondering, is whether I should have been checking it was still done up tight, or doing something to make sure it wasn't going to fall off? Or should I be ringing up the engineer that put it on and asking for some sort of compensation?

 

I was there when he put it on and he didn't seem to be the cutting corners type. And I've probably done 100 hours on it so it isn't like it fell off the week after it went on.

 

But at the very least I'd like to figure out how to make sure the next one doesn't fall off.

 

Any ideas?

Umm. Why did it fall off? That is the question.. Split pin not installed or incorrectly? Corrosion? Broken shaft? 100hrs is not long..

[raz88 97]

No idea why it fell off, the evidence left behind is a shaft that looks fine. It was a flex o fold prop. And it's a Volvo sail drive.

 

The guy who installed it did a beautiful job of re pinning and making sure the gears atc all worked.

As I was having him put it on I didn't pay as much attention as I probably should have to how it was attached. Should have done it myself and figured it out properly. Kind if figured it was a do it right and not worry about it again item rather than a tighten monthly kind of a thing.

[Elliot749 28]

I have a Volvo sail drive , and approx 2 years ago the same thing happened. It simply fell off, after being fitted by an engineer. There was no damage to spline / thread at all. It was 6 months after he had fitted it.

Insurance - no

Help from the engineer - no

I found a second hand ( albeit refurbished) KiwiProp and fitted it my self. Best thing that I ever did ! Fantastic piece of kit

 

As a precaution I purchased a second hand ( but rebuilt) Volvo 2 blade folder for very few $$$, and keep it ready to go in case a repeat “ prop disconnect “ happens

 

Hope you get some “help” from the chap who fitted it.

[rmiker 15]

Hmm. Found this: From http://www.cruisersforum.com/forums/f136/sail-drives-and-props-38652-7.html#post803465

 

Would explain it..

 

QUOTE:

Mahe’s

I received two reports of folding props falling off the sail drives. One prop on a Mahe 36 and the other on a Lipari 41.
Please make sure that you have a good stainless steel locking tab and that you make sure it’s folded tight up against the bolt when you install your folding props. These props have a three way safety lock on them. If the first one is not properly done over time the two other locks loosen up and fall off.

Mark

[wheels 544]

The info in the post above is good.

To add another couple of points. If the Prop is new, it comes with a special thread lock compound on the locking bolt. NEVER apply a liquid thread locker in addition to that already applied.
If the prop is being reinstalled, it is best practice to install a new locking bolt with flexofolds thread locker applied.
However,
if you reuse the lock bolt, you need to use a thread locker and Loctite 243(blue) is recommended.

Flexofolds own thread locker compound will cure underwater

BUT!
You MUST NOT put the boat back in the water till the 243 thread locker has the recommended amount of time to cure in air first. It will not cure underwater.

Another point often not done correctly is applying the correct amount of torque to the lock nut and lock bolt For the SD20, it is 50ft/lb. The SD50 requires 65ft/lb
And only 10.8ft/lb to the Lock bolt. Over tightening can be a cause of failure of the bolt.

While the saildrive has a splined shaft and the folling does not apply, if you happen to be attaching any prop to a tapered shaft, NEVER apply grease or any other such compound to the shaft. It MUST remain clean and dry for the surface to mate properly. Otherwise it will come loose.
 

[raz88 97]

Thanks all.

 

Guess I'm now in the market for a folding prop to suit a 34 footer with a Volvo 18hp and sail drive. Any pearls of wisdom on how to determine the correct size?

[Elliot749 28]

Raz88 I have the specs at work for my KiwiProp We too are 34 foot , 18hp Volvo with 120S leg. I’ll message you the specs. I also have my “spare” Volvo prop I can “lend” you if you need to get going sooner rather than later. It’s in New Lynn , Auckland and ready to bolt on (re pinned etc)

[raz88 97]

That would be awesome re the specs, thanks. I'll try and find a keeper before borrowing one, but will get in touch if I get stuck. Thanks

[Battgirl 23]

Elliot749 what performance difference do you have with the kiwiprop please? My current boat has the same engine and leg as yours. I had a kiwiprop on my previous boat and found it great

[Elliot749 28]

My observation was a great deal “smootherl” at 2300-2600rpm cruise. The KiwiProp is 3 bladed , and lighter than the Volvo Unit , and with KP I had about 0.7 to 1knt increase in speed , for same revs.

We do a lot of Motoring. A hell of a lot

[Island Time 1,288]

Yep, another vote for kiwiprop. Great units, with good support. They will know which size you need, give them a call. Cheaper than most as well.

Just remember whenever the boat is out, grease all 5 grease points, and make sure the reverse rollers can turn freely.

One advantage of kiwiprops is that it comes off easily to get at the anode on a 120s. I've done mine in the water several times...

[Fish 0]

The other thing you need to remember when sizing a kiwiprop, the pitch is adjustable, so all you need to do is select the diameter. Diameter should be the largest you can fit without cavitation issues. The suppliers are very good at determining the required pitch, but if it is slightly out, it is very easy to tweek with an alan-key. They do have an extensive library of boats, engines and props. All of their sizing information is available on their website, you just need to take the time to work through it.

I.e. you don't have to drop several grand on a prop and just hope that the pitch is optimal for your boat. If you want an extra 100 rpm at max revs, or a little more boat speed at cruising RPM, you can tweek the pitch until you are happy with it.