Shaft

[sanna]

We have installed a new engine, and the prop. is to close to the boat in front. Therefore we need to move the prop's position approx. 4 cm backwards. We have a traditional shaft with a flexible unit between the engine and the shaft.
We would be greatful for an advice !

Sanna
(from Oslo)

 

[Guest]

dont be so close to the boat in front! ask the yard to move the boat in front to somewhere else

Beth

 

[david_bagshaw]

The cheap answer is to have a spacer ring made to push the shaft back the required amount

or a new longer shaft.

You dont say if the flexible unit is a coupling, or a cv type shaft & thrust bearing, . if the latter a new shaft probably will be the only answer.

David
www.yachtman.co.uk

 

[ccscott49]

I agree with David, I think you mean a plastic semi flexible drive coupling, if so the spacer would be the cheapest option, or two semi flexs'.

 

[jfkal]

Very funny. But not very helpful

 

[sanna]

We have a plastic semi flexible drive coupling. I have been told by an engineer in Norway that the best solution is to replace the shaft, however, I try to find a cheaper alternative. I think of a spacer as a "unit" to fill the 4 cm gap between the engine and the flexible coupling. Do you think another flexibel coupling can do the job - they should probably be linked together with long bolts? If I have to make a spacer from steel this probably will cost us more than a new shaft (the price for a new shaft in Norway is + GBP 100)?
Thank you for the help so far!
Regards
Sanna (in Oslo)

 

[vyv_cox]

Adding another coupling to the existing one may give you a lot of problems, especially if the mountings on the new engine are softer than the old. There is a real chance that the shaft will contact the stern tube if the overall flexibility is too great. Before trying to make a spacer, speak to the people who supplied/fitted the engine and find out about the mountings. You may even need to fit an Aquadrive, as I have just done. In that case you will need to cut the end off the shaft, so you would regret buying a longer one!

On your last point, I would not expect a spacer to be very expensive. You only need a carbon steel disc, 4 cm thick and the diameter of the coupling flange, with bolt holes right through it. The materials and time don't approach that required for a new shaft.

 

[pandroid]

Maxprop (Darglow Engineering) make these spacers, already drilled to fit a range of popular gearboxes. They vary from 5mm to 40mm

 

[dickh]

You can buy split 'muff'couplings which join shafts of the same size, with 4 clamp screws, then you would only have to fit a short length of shaft to make up the length. You would probably have to shorten your existing shaft to allow for the amount in your coupling and the muff coupling. Try Fenners, BSL or similar power transmission distributors.

 

[ccscott49]

I think two flexes would do, with long bolts, I would always carry a spare afterwards!