Refitting a prop

[revolver]

Hi. Im new here so I hope Im doing this right.

I have a problem. A friend told me this was a good way to find an answer.

I removed my prop to put on a rope cutter. That was no problem. Now I need to put it back. I have tried over and over, but I cant get it on the shaft far enough to make the hole in the nut line up with the hole in the shaft. It needs to go a bit more than a quarter turn extra.

I have tried jamming the prop with a long length of wood and heaving on the nut with a big ajustable but Im still 1/4 turn short.

My neighbour says just hit it with a hammer, but I dont like that idea. Wouldnt that be just the same as hitting my engine with a hammer? My neighbour says the engine is designed to take pounding in rough seas so I dont have to worry.

Can I just thump it, or is there a better way?

Some help would be appreciated as I am being launched next week. Thanks.

 

[tcm]

the mating surface between the inside bore of the prop, and the outside of the propshaft is quite accurtate. Any cack on there, or big loads of grease, and it may not fit close up enough to get the nut on enough. The main thing is getting that prop on far enough first. Clean up prop and shaft these with usual stuff, plastic dishwashher sponge, perhaps mild sandpaper (only a bit mind) praps some white spirit, really clean. Put prop on, try the nut. If that don't work, nut off, tap prop a bit but carefully mind, and try again. And it will work.

unless of course yer ropecutters are the wrong size...

 

[savageseadog]

Is the prop mounted on a taper? The most important thing is to make sure that the prop is securely on the taper, yes you should tap it on but not whack the c**p out of it. If it is on properly and the hole doesn't line up I've done something like this before. I lapped the mating surface of the nut down on a piece of wet and dry. Put it on a really flat suface and keep checking until it lines up.

 

[john_morris_uk]

Check that the keyway and woodruff key is clean and that the key is in the right way. The prop should sit on its taper and the key should not have any pressure on its upper or lower surfaces. It is there to ensure that the prop doesn't rotate. Sometimes keys can be put in the wrong way and that stops the prop seating properly.

 

[mbay]

i had a the same type of problem, we solved it by wrapping fine nylon string a couple of turns round the shaft this acts as a spring and keeps the nut tight it also allowed us to aline the hole on the shaft with the one on the nut. the other advice you have is all good make sure your prop and shaft are squeaky clean.

 

[ajt]

Just a thought, my Father has had to heat up the prop with a blow torch in the past, to remove and refit it maybe this would work for you.

 

[Andrew_Fanner]

Differential expansion between prop and shaft may affect you. What materials are the sfat and prop made from?

I have always had, as an article of faith, that a smidgen of waterproof grease on the tapered shaft is a good plan as it makes removing the prop easier if you want to do so.

 

[AliM]

I'd suggest wrapping the shaft is a cloth and keeping it cool (ice, water, something). At the same time warm up the prop. A cloth soaked in boiling water may be enough, a blowtorch may be excessive. Everything very clean, and a bit of lubrication should get that final quarter turn. Gntle persuasion with a mallet will complete the job. Good luck.

 

[revolver]

Thanks for all the replies. To answer some of your questions...

The shaft is stainless and the prop is bronze, or whatever it is that props are made of. The shaft is tapered to fit the prop. I did clean it up as best I could with a green scrubber pad but I have not tried any emery paper.

 

[duncanmack]

Mebbe a daft point, but have you misplaced a washer?

 

[oldharry]

Check the key and keyway: any gunge in the bottom of the key grooves or on the key will stop the prop seating properly. Remember to check the keyway in the prop as well as the one on the shaft. Make sure the key is in correctly, and is not moving as you put the prop on.

 

[roboandkate]

If your sure the prop is sat properly on the taper and just want an extra 1/4 turn to get the pin in, take a file to the back of the nut and just take enough off to get the extra 1/4 turn.

 

[TheBoatman]

This has been aired before and the only way to solve your problem is to "fit" the nut if you want it to line up with the original hole i.e. file the base face.

Tapers by there very nature are friction drives so provided the 2 tapers are matched no amount of whacking or thumping will get you your extra 1/4 turn. Heat will give you a little bit extra but be prepared to struggle to get the prop off next winter.

DON'T put grease or oil on the taper as that only serves to lessen the friction drive. If the taper is matched between prop and shaft the key has little effect as it's friction that is doing the driving job - It's a bit like belt and braces.

Peter.

 

[revolver]

Thanks everyone. Ive got it back on now. I did a bit of lots of things suggested here. I took out the key and cleaned the key and the shaft again with a plastic scrubbing pad. I used some very fine wet and dry on the shaft and made it shine. I laid a bit of coarse wet and dry on a table and rubbed the nut round and round in circles on it to clean up the back face. When I put it all back together the hole lined up. Thanks again.

 

[TheBoatman]

Don't you just luv it when a plan comes together /forums/images/graemlins/tongue.gif

Peter.