Thanks for all the help, I have decided to buy an ally prop first just to give it a go and see wether the one I buy is right before going for the stainless baby.
I have bought the one on ebay - £60 seemed dead cheap and I had a few quid in my paypal balance.
This may sound really stupid but can anyone just point out what the numbers mean
I guess the pitch is the angle of the blades and the other measurement is the diameter?
So the one I got : 12 5/8 x 23
I guess the 12 5/8's is the pitch and the 23 the size of the blades?
Sorry for sound stupid