Propeller help

[CSeils]

I have a question about pitch vs. size of the propeller. I am working on building a scratch built ski type boat. I will be using a .19 gas engine. Boat size is approx. 14" x 24". What size prop do I use? Is there a formula or just a hit and miss approach?

Thanks for any help.

[Doubledog]

If you're planning to run it, then you need to look at engine loads. In other words how much prop can the engine turn & get maximum performance.

Engine is a .19 - alright, what engine?

Drive system - is it going to be submerged or surface? This will effect prop size also.