Prop shaft taper

[farmhouse]

I have a Volvo D1-20 engine driving a Volvo 25mm shaft and 2 bladed prop. I am planning a new feathering prop but so far have been unable to find the taper details and the nut details.
I do not want to lift the boat to measure these things if I can help it. Can anyone help?

 

[AliM]

When we had a serious prop problem in the Netherlands, we found that our shaft was 1 inch, and the taper was 1 in 12. The best the engineer could do for us (quickly) was 25 mm and the metric standard taper (he said, anyway) of 1 in 10. It fitted - sort of - well, it got us home.

More details of the boat and year may allow other more knowledgable forumites to help further, but you are going to have to take a big chance unless you measure properly. If it's a new boat, then you may be able to get that info from the manufacturer, or there maybe a helpful users association.

Lift, and get it measured properly, would be my advice.

 

[Heckler]

asap do a little booklet with such info in, try their website www.asap-supplies.com
Stu

 

[Tranona]

The Prop supplier will almost certainly have the correct details. The taper and nut will be a standard item, but most folding/feathering props use their own nut.

 

[pathfinder]

I had a volvo md11c (1978) driving a 25mm shaft and 2 bladed prop the taper was 1in 20.I think this was a standard for volvo at the time.

 

[nct1]

Are you going to refit it under water ?

If not, agree price and delivery with the supplier, and provide the old prop as evidence of the taiper.

 

[farmhouse]

No not going to fit under water! Just trying to avoid two lifts - one to measure one to fit. Thanks for your advice.

 

[maxi]

"Usually", but not in all cases, a metric shaft is a 10:1 taper and an imperial shaft 12:1.

 

[Eygthene]

Plan to do it when it is out next winter. Unless you can afford the cost of the two lifts now.

 

[davey]

Three common marine tapers that I know of are the Metric 1 in 10, the British 1 in 12 and the US Society of Engineers 1 in 16 taper. Whilst a Metric 1 in 10 propeller can be reamed-out to fit a 1 in 12 British shaft, the US propellers can be a problem. Some US propellers don't even have a tapered bore! Instead they are bored parallel and fixed with a bolt. This method is popular on boats that are used in the swamps as one can surmise that it is much easier to remove a bent propeller if it is not on a taper. Good luck!

 

[Billjratt]

Your profile doesn't give a location but if it's tidal why don't you a find wall and take measurements when it dries.

 

[charles_reed]

My original Bukh shaft had a 15degree taper (apparently unique to Bukh), so the Autoprop was made to the same taper and the replacement shaft, in Seville, to the same 15degree taper (which I assume to be 1:0.083333.
An added excitement was the use of a metric bsp thread for the nut. Even the builder thought the shaft was a 1", as they're easy to measure I soon foung out it was actually 25mm.
As there seem to be such variability in prop-shaft tapers, I'd take the boat out of the water, remove the current shaft and let whoever is supplying the new prop have the shaft.
No guesses and no wasted money.

 

[Tranona]

As there seem to be such variability in prop-shaft tapers, I'd take the boat out of the water, remove the current shaft and let whoever is supplying the new prop have the shaft.
No guesses and no wasted money.

Would imagine he already has it sorted as the enquiry was nearl 6 years ago.

BTW newish Volvo installation so would have been a standard 25mm 1:10 taper.