Fitting a prop while in the water?

[TandC]

Okay - so feasible... not ideal.. but doable perhaps. 

 

I should have said, there is no prop on there currently.  

It's hopefully slide it on... washer/nut on... tighten up... . split pin through and bent....   whether or not the prop will fit through the weedhatch is a different story. 

 

this is all just theoretical at the moment anyway, I am just considering options on whether I can get the boat mobile without a slipway. 

 

[Tony Brooks]

1 minute ago, TandC said:

Okay - so feasible... not ideal.. but doable perhaps. 

 

I should have said, there is no prop on there currently.  

It's hopefully slide it on... washer/nut on... tighten up... . split pin through and bent....   whether or not the prop will fit through the weedhatch is a different story. 

 

this is all just theoretical at the moment anyway, I am just considering options on whether I can get the boat mobile without a slipway. 

 

 

There seems to be two "standard" tapers used on props, so I doubt that you could ensure the prop properly fits the shaft taper and key in the water, there is also a question about what thread the prop shaft has been machined to. So I think pulling the shaft as described by others will be the only way likely to produce a reliable long term result.  That is not to say putting a prop on and doing your best would not allow you to move the boat, but there would be a good chance the prop may slip on the shaft or fall off.

[TandC]

1 minute ago, Tony Brooks said:

 

There seems to be two "standard" tapers used on props, so I doubt that you could ensure the prop properly fits the shaft taper and key in the water, there is also a question about what thread the prop shaft has been machined to. So I think pulling the shaft as described by others will be the only way likely to produce a reliable long term result.  That is not to say putting a prop on and doing your best would not allow you to move the boat, but there would be a good chance the prop may slip on the shaft or fall off.

hmmm..   The prop shaft is new (relatively) and so I could ask the supplier perhaps to try to ensure a match... but this is the sort of issue I thought likely.   Just hope it doesnt come to it. 

[magnetman]

Get spare split pins in case of droppage. 

It seems quite awkward to line up the holes in the nut and shaft. Also has the shaft already been drilled for the pin? If so is it in the right place? No use fitting the nut too far back or the prop might rattle about under hard reversing. 

 

Definitely seems a lot easier to do this on a bench. 

 

 

 

I found it quite difficult to drill the prop nut and shaft in the right place even with the whole lot on a bench. I think there is still a broken drill bit in that propshaft somewhere. 

[Biggles]

44 minutes ago, TandC said:

Okay - so feasible... not ideal.. but doable perhaps. 

 

I should have said, there is no prop on there currently.  

It's hopefully slide it on... washer/nut on... tighten up... . split pin through and bent....   whether or not the prop will fit through the weedhatch is a different story. 

 

this is all just theoretical at the moment anyway, I am just considering options on whether I can get the boat mobile without a slipway. 

 

That should be pretty easy then. Getting the old one off is the hard part.

[nb Innisfree]

Don't forget to tie a rope to a blade (& to the boat!) 

[magnetman]

On 26/03/2025 at 08:58, TandC said:

is there a keyway on the prop shaft?  

Yes.

[Tonka]

Back end of boat on the lock cill.  Stand on lock cill. Job done

[magnetman]

2 hours ago, Tonka said:

Back end of boat on the lock cill.  Stand on lock cill. Job done

Or find a short pound and accidentally leave paddles open on the lock below. 

There was a song by Peter Gabriel about it. 

Your own...personal...dry dock. 

 

 

[booke23]

5 hours ago, magnetman said:

Or find a short pound and accidentally leave paddles open on the lock below. 

There was a song by Peter Gabriel about it. 

Your own...personal...dry dock. 

 

 

If you're near a staircase lock you could achieve the same....you would even have a fixed ladder going down to the dry dock just like a real shipyard! Although leaky gates might make it a little wetter than ideal. 

[ditchcrawler]

19 minutes ago, booke23 said:

If you're near a staircase lock you could achieve the same....you would even have a fixed ladder going down to the dry dock just like a real shipyard! Although leaky gates might make it a little wetter than ideal. 

I don't think he has a prop on to get there 

[booke23]

10 minutes ago, ditchcrawler said:

I don't think he has a prop on to get there 

 

There's never a staircase lock around when you need one!

[agg221]

A few thoughts:

 

Adjustable spanner across the threads and then measure the gap is a reasonable way to figure the diameter for the nut. If you can see the threads then measuring the threaded length the same way and then counting the number will give you either a metric pitch (mm per turn) or imperial threads per inch. A quick Google search will then confirm that this is standard - both metric and BSW shafts are commonly available so worth checking.

 

Drill bits are good for finding the diameter of the split pin hole.

 

A piece of thread or fishing line through the eye of the split pin is a good way avoid losing them.

 

A castellated nut is a good option to avoid having to achieve high accuracy in placement of the split pin hole. Tight and a bit more to expose the hole is good.

 

Not sure how you would lock the prop shaft from turning. On land, a piece of wood wedged between the prop and the ground works. It would need something inboard on the coupling I suspect.

 

Alec