G'day Doonie,
You are a bit closer to water than I am here!
Image of the installation attached ( I hope ). The pulleys I make myself from either aluminium or perspex, whatever I have on hand at the time. Size is as they come off the lathe, I don't measure, just eyeball it, and if they look OK, that'll do! The ratio is whatever it comes put at!
The 1/4" polyurethane belting is hollow, and is joined by aluminium studs, so the lengths can be adjusted to suit. It's called Redthane Belting, and is, or should be, readily available from Engineers Suppliers. I used to work for one, so I have a lifetime supply in stock.
The 6" prop is one that I made from a turned brass boss and shaped heavy brass sheet for the blades. Haven't a clue what the pitch is, but it"s big, and it works at very low revs and shifts a lot of water. Not as pretty as those from the likes of the Prop Shop, but 35 years ago we didn't have too many options for big props off the shelf, and as that was before long the Interweb, information was hard to come by easily!
Used to have to write letters back then, and if you were lucky, a reply within 3 weeks from the UK! We are so spoiled by our modern technology!
Ian.