Installing a prop

[grinfax]

OK, so my prop fell out, lost at sea. Fortunately the previous owner gave me a spare prop, presumably the original prop with the boat, since the lost one was a folding prop. I went diving under the boat and the spare prop fits perfectly on the shaft. But I can't figure out how to fix the prop on the shaft.

Here is what my situation is:

- The shaft has a conical shape the prop fits perfectly in it.
- 2 blade bronze prop
- The shaft has a groove, so does the prop. I am guessing I need some sort of pin in there to align the shaft with the prop so it does not spin.
- I am guessing I need some sort of nut to lock the prop in place.

So clearly fate has yet to give me a new lesson on how to fix my boat. Here are the questions I have:

1) Do I need to take the boat out of the water or is this something I can fix with scuba gear?
2) What is the pin that prevents the prop from spinning on the shaft called? Where do I get one?
3) Do I need one or two nuts to fix the prop in place? It seems some props have a conical nut, others have two nuts and others just have one.

Any advice would be much welcome. This is the first time something like this happens to me, I don't have a big budget, so I'd like to do as much as I can myself.

Also, I googled for tutorials, but could not find any. If you know of one, please post.

Thank you,
Kim

[GulfTriton]

The "pin" is probably a woodruff key. Google them and see it that's what you need. They come in a billion and one different sizes. I could probably fix this with just one breath, but I'm superhuman, so a haul out should not be necessary. Two nuts or one nut depending on the setup. I would use one nut if I could put a cotter pin in it or two nuts otherwise.

[Faster]

Originally Posted by grinfax

Here are the questions I have:

1) Do I need to take the boat out of the water or is this something I can fix with scuba gear?
2) What is the pin that prevents the prop from spinning on the shaft called? Where do I get one?
3) Do I need one or two nuts to fix the prop in place? It seems some props have a conical nut, others have two nuts and others just have one.

1. This can be done with scuba gear, but will be best done by an experienced diver.(which you may well be....)

2. You need a keypiece - ie a piece of keystock. You'll need to know the dimension (ie 1/4 x 1/4 or ?) and how long it needs to be (probably around 3") From recent experience I can tell you that the key piece grooves may not be consistent and the key may need some shaping and filing to properly fit. You need to make sure the prop slides all the way up the taper with the keypiece in place.

3. Depending on how much thread is left on the shaft you may have room for 2 nuts. Alternatively you might try using thinner 'jam nuts'. If there's only room for one nut (the shaft may have been modified for the folder) then it needs to be pinned in place which means drilling - suddenly underwater is less likely unless the shaft is already drilled.. Another possible option (but less secure) may be to drill and tap the nut for a couple of set screws ahead of time.

Take a piece of 2x4 down with you to jam between the prop and the hull so that you can properly tighten the nut(s) without trying to turn the engine or gear.

Good luck!

[JimsCAL]

You need the key, nuts and a cotter pin. These guys can help you.

Boat Propellers, Inboard Propellers, Cutlass Bearings, Zinc Anodes, Boat Shafts, Shaft Seals and so much more...

[Fstbttms]

Take a wander around a boatyard to see what other typical prop/shaft/nut arrangements look like. Then go to a local prop shop with your prop and your shaft diameter measurement. They will sell you a properly fitted key and nuts. Remember that you will need a cotter pin (assuming there is still a hole drilled for one at the end of the shaft.) Then get in the water and do the installation. To immobilize the prop, I like to use a length of 2X2 placed between the strut and rudder. Good luck.

[grinfax]

Thank you for your replies... as always I feel more confident now. Off I go!

[Silvio]

Don't forget the S.C.U.B.A gear!
Good luck.

[dhays]

My guess it was the lack of a cotter pin than caused the prop to go swimming. This is where a periodic inspection of the bottom can be worth the expense. I'm in cold water. I pay a diver to give the bottom a scrub, inspect the bottom, and inspect and replace the zincs as needed. Since boats don't get hauled yearly here, it is well worth the expense.

Having said that, I'm going to haul the boat in a couple weeks to have a new (autoprop) installed. For a standard fixed prop, the divers do that all the time relatively cheap.

Dave

[Fstbttms]

Originally Posted by dhays

Having said that, I'm going to haul the boat in a couple weeks to have a new (autoprop) installed. For a standard fixed prop, the divers do that all the time relatively cheap.

No reason your diver can't install your Autoprop. I have done many.

[rbrasi]

If you don't have a hole for a cotter pin, get what's called a "European lock". It looks like a washer with Mickey Mouse ears that aligns with the keyslot and the ears fold down over the bolt to keep it from moving.