Prop Fell Off! Help!

[Morgan Paul]

This might be of some help.

http://www.yanmar.dk/files/SDOperati...stallation.pdf

[Steve Pope]

Thanks Alan that is basically what I thought it would have had to to be. And as you say putting lubricant on the taper is a definite no no. loktite on the threads yes yes.

[ssullivan]

Originally Posted by Alan Wheeler

No absolutely not.
The prop nut should be tightened to the correct torque. This pulls the prop onto the shaft and if it has been done correctly, the nut should be able to be removed and you should not be able to pull the prop off with out a smack with a hammer. The safety system is the Nut and the set screw. There simply is no way either can come out with a wobble of the nose cone. The nut is there for the one reason of ensuring the prop does not come lose due to improper gear changing, like that clunk when put into gear when the engine still has too many revs on it. That is not the best for things. The set screw is the "Lock" for the prop nut. The two can or should not be able to simply come loose. Even with a vibration of the nose cone.
The issues will be....The anti-seize applied to the shaft has stopped the prop pulling up properly onto the shaft. The prop has worked it's way on over a long period of time while the engine is in gear and the prop pushing hard onto the shaft. Therefore the nut will now be loose and the set screw may possibly also become loose. Not sure how, but obviously it has.
Sean, the drawing only shows the splined shaft, but I assume the tapered the shaft also has a keyway, is that correct??

When using the cone option (as opposed to just the nut and set screw), the cone *becomes* the prop nut. The cone has threads inside that screw onto the prop shaft. There is indeed a hole through the cone you insert a long screwdriver or something into and torque the cone onto the prop shaft. After the cone is tightened, there is only the single allen bolt that goes through the center of the cone and into a female area on the prop shaft itself. There is no "prop nut" aside from the cone and allen bolt.

There is no keyway at all. There is only the cone and allen screw, or in the other case of hardware available, the prop nut and allen screw. No key, no nothing. Only the torque on the prop nut or cone and torque on the allen bolt holds the entire assembly on.

As is often the case on forums... now I'm getting more confused and need to rush order the parts this AM. Damn...

[ssullivan]

Paul (and Wheels and Steve):

The imaged attached to this post shows *exactly* what I have, thanks to Paul's link to the installation manual.

There is the cone which *is* the prop nut, and only that allen bolt that holds it in place. I didn't see the "washer" component on my port prop. It wasn't there at all.

Now, given that the Yanmar diagram shows applying grease to the splines before the prop goes on... are you absolutely sure I shouldn't, Wheels?

Thanks for the help.

[Morgan Paul]

More info on SD20

Propeller Shaft

[ssullivan]

Originally Posted by Morgan Paul

More info on SD20

Propeller Shaft

Thank you very much, Paul! Wow! Good info.

I was missing the washer between the cone and the prop and my port prop cone looks exactly like the one pictured in their "starbord" cone photo. It was damaged just like that.

I think the loctite is the way to go... I think I may use blue though, since red requires heating with a torch to 250 deg F for removal.

[Pelagic]

Wow! it is amazing what can be discovered when we all share info like this....Well done Paul!

Good luck with the repairs Sean and I hope you are not in the doghouse with the missus

[SeaKing]

I replaced my cone with the nut after losing my prop last season. The nut style was easier to torque properly, especially underwater. That was recommended to me by an owner of a boat like mine. He knew of quite a few who had been down the same route. The standard style nut and allen head screw was the best way to go also cheaper than the cone. You may have a little turbulence behind the prop but I don't believe it effects me enough to worrry about that. Also the hex screw from Yanmar comes with a small dot of green thread lock on it. I just removed mine on Saturday and it was very tight after the underwater installation last year.

[imagine2frolic]

SULLI,

I lost several props in one season. I lost it on the port side each time too?????? I eventually grinded down a flat spot on the bolt through the back of the cone. I inserted a small broken flat screwdriver tip with a small hammer to stop the bolt from rotating. All this done while the boat was in the water with snorkel gear.

It lasted another 1000 miles like this until I could haul the boat. I used blue loc-tite to reassmble the props, and have 2 spares. The cones, nuts, washers, and bolts were as expensive as the props themselves.....OUCH!

[ssullivan]

I know... it's a sucky situation. I've managed to locate the cones, hardware and all that. They are in stock in Annapolis (car rental - oh boy, another expense)

But... I can't (for the life of me) find a 16.5" x 12 aluminum, 2 bladed fixed prop anywhere!!

Does anyone know where I can find one in stock (aside from the bottom of the Chesapeake??)

[2divers]

have you tried them?
410-267-8681
they seem to have about everything you could need in Annapolis.

[ssullivan]

Originally Posted by 2divers

have you tried them?
410-267-8681
they seem to have about everything you could need in Annapolis.

Check. They don't carry these props.

Thanks, though.

This is annoying as it gets, because I found everything but the prop. I could be underway right now if I could only find a prop!! RRRR!!!!

[imagine2frolic]

Sulli,

When I lost my first prop it was in Miami. I went to a dealer there, and they had what I needed. Reading this thread reminds me to look for my extra props tonight since I am leaving in 13 days, and I will look for the distributor's invoice too. Hopefully you will have found something by morning......GOOD LUCK!!!!!!

[svcattales]

Sully, You might want to check out the thread in this "propulsion" section called "underwater loctite." I had a problem with my saildrive zinc coming loose twice and found there are different types of loctite. You want the one that comes in stick form like Chapstick. It has a waxy consistency and will bond underwater. The liquid form doesn't bond at all. Blue Stix loctite is called 248 and red is 268. I would use the red since I use it to assemble my folding props and it does come apart with some torque. You need to let the loctite cure in the air for a few hours before assembly in the water. Good luck with the prop.

[josef]

Just lost my port prop on 10 year old FP Bahia on passage from North Africa .Underwater inspection reveals that shaft has sheared where it reduces to take the cone and allen key.Yanmar did not appear very concerned.Still trying to get some form of compensation.Appears now they have changed type of shaft and cone but was there ever a recall or advice to owners of this design problem/fault? The starboard prop could presumably go at anytime with potential catastrophic risk to crew and vessel.