Prop key for 2004 Jeanneau 43ds

[SaltyMetals]

I have a 2004 43ds and need to know the length of the key that goes in the slot in the prop shaft underneath the prop. I have measured my slot as being 10.2mm wide but does anyone know the length of the key that goes in the slot?

For some reason my slot has been machined to a width of 10.2mm when i understand the standard is supposed to be 10.0mm so i am getting too much rotational play with my original key which has a width of 9.9mm. I need to have a new , slightly wider, key to be made but need to know how long it has to be.

It would be most useful if any of you hv this info.
Thanks
Andrew

[SVHarmonie]

The key is easy to cut, so why do you need it a precise length?

But, courtesy of google, here is the ISO prop shaft standard:

ISO - Shaft standards

If your key was undersized, it is possible that your keyway was abused enough that it either enlarged itself, or needed to be enlarged, to use a larger key. This is kind of a half-assed sloppy way of doing things.

In the ideal world, you would lap your prop onto the shaft taper so it fit well enough that minimal rotational torque was transmitted to the key.

If it was me, I'd pull the shaft and have a PROPER keyway cut opposite to the original, now compromised, keyway.

Will you actually be able to get 10.2 mm stainless keystock? I have never seen it. And how will that impact the keyway on the prop?

[slug]

Originally Posted by SaltyMetals

I have a 2004 43ds and need to know the length of the key that goes in the slot in the prop shaft underneath the prop. I have measured my slot as being 10.2mm wide but does anyone know the length of the key that goes in the slot?

For some reason my slot has been machined to a width of 10.2mm when i understand the standard is supposed to be 10.0mm so i am getting too much rotational play with my original key which has a width of 9.9mm. I need to have a new , slightly wider, key to be made but need to know how long it has to be.

It would be most useful if any of you hv this info.
Thanks
Andrew

From the shipyard

Your installation and prop may be different

[SaltyMetals]

Many tks to both Harmonie & Slug. Most useful.
Andrew

[Cadence]

As an uneducated guess, at some point the shaft nut was not made up correctly and reverse let the prop pack out of the taper placing the load on the key.

[SaltyMetals]

I think i am making progress here but my question is what type of stainless key stock is used to make the key? The only material that the prop manufacturer can offer me is brass and that would be no good at all.

I intend to purchase some key stock material and simply machine it to shape which will mean starting with 12x12mm square and then machining to fit the keyway in the shaft and machine a little more with a slight step to fit in the keyway of the prop.
Andrew

[SaltyMetals]

What i shld have added is it a standard 316 stainless or is it hardened somehow to work as a key?

[fstbttms]

Don't use stainless. Too difficult to work. Buy some bronze keystock in the right size. A file will quickly and easily modify it if it's too big in any dimension. Don't overthink the length, it's not critical. 1" to 1.25" will be fine.

[Cadence]

Using stainless for key stock? JMHO

[AKA-None]

No stainless the key shouldn’t be taking a lot of force. The primary force should be the prop to shaft taper

[SaltyMetals]

I think the old (existing) key is some sort of steel, not bronze. I appreciate the point that bronze would be easier to work but with the right sort of equipment in a machine shop it shld also be easy to use stainless. Would that be correct?

Many tks guys for your advice

Andrew

[fstbttms]

Originally Posted by SaltyMetals

...with the right sort of equipment in a machine shop it shld also be easy to use stainless. Would that be correct?

No doubt. But why not just take the prop to a machine shop and ask them to fab a key for it? If you're going to have professionals do the job anyway, why are you doing all this legwork?

[SaltyMetals]

I thought it would be easy enough to find the ket material but my prblm is that the keyway on the shaft is about 0.3mm more than the keyway in the prop when it should only be 0.05mm so i am going to have to find an oversize key and then machine it down with a step.
Prop manufacturer said they can only offer brass keys and i don't think that is hard enough. needs to be stainless. Anyway, thanks to this discussion w you guys i can now see my way forward.
andrew

[fstbttms]

Originally Posted by SaltyMetals

Prop manufacturer said they can only offer brass keys and i don't think that is hard enough. needs to be stainless.

Right. Because you know more about it than the prop manufacturer. The fact that you think bronze isn't "hard enough" is proof that you don't. It also illustrates that you don't understand how the taper and key concept works. No offense intended but you are making this more difficult than it has to be. But hey- it's your boat and your dime.

[Sailmonkey]

Bronze is plenty hard.

If the taper is correctly machined you don’t need a key at all, it’s the taper fit (interference) that drives the prop, not the key.

Look at a Morse taper drill bit, it’s not even held in place with a nut, yet doesn’t spin with enormous torque applied to it while drilling through steel.