Nuts on Props

[Ruffles]

Had the prop off at the w/e to do the cutless bearing. Shaft drive with a taper. The dome nut was quite tight to get off but the prop came off with a puller fairly easily.

When I put the prop back on I knocked it on to the taper quite gently with a pin hammer and a wooden block. When I then put the dome nut on I found that I only needed to tighten it a quarter turn for the split pin hole to line up. In other words the nut is not on that tight. Certainly not as tight as it was.

Is it acceptable to put a washer between the prop and the nut? The alternative is to drill another split pin hole in the nut.

BTW I greased the taper before fitting the prop. Is that a mistake?

Thanks,

Rob.

 

[Phoenix of Hamble]

Will it not go another half turn?

 

[dickh]

Try another half turn - it'll probably go up enough. Yes a thin smear of grease makes it easier to remove the next time.

 

[Ruffles]

No. It's not a castle nut - it's a dome nut with a hole. Is this usual?

It might go another 60 degrees. If so I will need to drill another hole. However a stainless washer seems a good solution? If I can get one big enough...

Rob.

 

[Phoenix of Hamble]

I'd be inclined to identify the reasons why the prop is sitting differently first......

 

[Phoenix of Hamble]

Just another thought.... the inside of the dome is clear of grease isn't it? hydraulic effects could lock is solid otherwise.....

 

[Lakesailor]

Do you remember the nut coming off after only half a turn? If not something has changed. An obvious thing to say perhaps, but you need to check out the problem.

 

[nedmin]

Are you jamming the prop.with a piece of wood on the ground?before tightening.If youve got a good size spanner it is ok to hit it with a hammer,but dont hammer it for all its worth! You wont be able to fit a washer because unlike a castellated nut you have only one shot at it where a castellated nut has 6!! you also have axial adjustment as the nut "slots" are open If it was me I would try to get a castellated nut. If you cannot, I would ascertain that the prop. is on correctly then redrill at rt.angles.It is possible that the prop. was heated before it was fitted,thats why you cannot line holes up.

 

[Ruffles]

So the consensus seems to me that the nut should be a LOT tighter. I think I'll try to source a castle nut.

Thanks all for the advice,

Rob.

 

[tcm]

Re: No grease

that's an interference fit: grease will reduce the friction and hence increase the load on the woodruff key and hence increasing the chances of a failure at that point. I wd install dry. No problem with washers, bvut better to find the torque values and use machined shim washers to achieve the right torque with the hole lining up.

 

[Ruffles]

Re: No grease

tcm

That makes total sense. Greased, the pressure on the prop hub will be the force on the nut multiplied by the taper ratio. Easily enough to stretch the bronze. Fortunately I haven't tightened beyond the original position.

I'll degrease it and try again. I've also asked Moodys for advise. They might know the torque requirement.

Many thanks,

Rob.

 

[Lakesailor]

Re: No grease

Did someone mention Woodruff key?
Are you sure it's not ridden up the groove and is jamming the prop away from it's proper seating on the taper.

 

[tcm]

oops

a woodruf key is semicircular innit...it should be a nordinary key in a routed slot so no room for movement of the key i think, yes? sorry

 

[Ruffles]

Re: No grease

Nope. It has a square key. Which appears to be brass and fixed permanently into the taper. Bit of a squeeze getting the cutless bearing over it.

Rob.

 

[FlyingDutchman]

Re: No grease

My question would be if the hole in the shaft and the holes in the nut line up axially.
You can probably see through the hole or feel with a small drill bit.
This will make clear if the nut has to be tightened another half turn or not?

 

[ashanta]

(IMHO)The position really should have been scored before removal. the responses so far are realistic in that there should be the ability to get back to original position. If the size of the split pin hole is such that you can get another 90 degrees that may solve the problem but I hate to say that as layman and not a qualified engineer I would have scored the position and counted every revolution of the nut on disassemby and recorded the figures..
I know this is no help and do hope you sort the problem out.
Regards.

peter.

 

[pampas]

I presume that when the prop was off that you polished the shaft? If this is the case then the prop has gone further up the taper.

Do not use a stainless washer,rather get hold of a bronze washer, file to the thickness required, tiring I know, but have done this sort of thing many times for other boaters. Make sure befor you start that the thread in the nut is in good condition all the way to the bottom and that there is no residual matter left in the hole at all.