Help sizing fixed prop for SO40

[Aced]

I have a 2002 SO40 with a Volvo D2-55 engine and ZF gearbox. The MaxiProp isn't giving drive in reverse, so I'm sending it for service. In the meantime, I want to fit a fixed prop but can't find the correct size. Does anyone know the original fixed-prop dimensions or the gearbox ratio so I can calculate it?

 

[Bridgingthegap]

The diameter is 18 inches, that part I'm sure of, but if I remember correctly, these came with several transmission options with varying ratios which will determine the pitch. The ratio should be on the gearbox somewhere.