Propshafts

[dunnroamin]

Folks,

It's time to re-engine. Currently I have a 16hp Sabb running through a 1" bronze shaft. Any thoughts as to the the upper limit of engine size I should go for? I'm thinking of something around 25hp, anyone got any simple formulae for calculating shaft torque capacity? Needs to be simple as I have the mathematical ability of a plant pot.

Cheers,

Simon

 

[Jcorstorphine]

Simon, have send you a "private message" to e mail me and I will forward you a couple of excel spread sheets to calculate all you need to know.

John C

 

[jleaworthy]

If past experience is anything to go on your shaft will not be the right length for the new engine and, if too short, you'll need to buy new anyway. Stainless stel will probably cope easily with any engine you can get in the available space but it's the transmitted torque that counts - not the power. The torque will be determined not only by the engine and the gearbox ratio but also by the size of propeller fitted. Take the advice of the engine manufacturer. Good luck

 

[JerryHawkins]

I have a 1" shaft for my Yanmar 3GM30 (27HP), so you should be OK on that front. If shaft is too long it can be cut, if too short you could introduce a flexible coupling and/or spacer depending on just how short it is!

If you decide (or need) to go for a new shaft, I can recommend Teignbridge Propellers (http://www.teignbridge.co.uk/ancills/temet.htm). They made me a new shaft out of "Temet25" stainless. Good service, good price.

Cheers,

Jerry