Prop design 3D print small electric boat

Hello,

sorry I’m new to this, I like to build thing and my next small project this spring will be a small boat

The boat will be 2,5m long/small classic looking plywood creation and the engine will be an electric converted outboard.

It’s an old classic Swedish Husky from 1961, original 80cc 4hp. 4200rpm geared down to 2300rpm on the propeller, 3 blade 190mm diameter 150mm pitch.

The prop is quite well-worn. I have access to some professional 3d printers (plastic) so I think I will take the opportunity to make a new one. What do you then think I should change then?.

I can fit a 200mm diameter maximum, the electric motor that I will produce the same rev ~4000rpm, but I assume the characteristic is slightly different from the original combustion engine.

The motor is rated continuous power 3000W and peak power 6000W.

I don’t have a clue about prop design.

This is how the stock unit looks like. was 190mm (7,5”) diameter (slightly less now…)

The pitch looks like this, obviously then 150mm. (5,9”) I don’t really understand to how to measure that, I just found the fact on an old brochure

I made a quick model 200mm, sort of the same visual pitch angle.

3 blade

or would a 4 blade be better?

What do you think about these? Any further input?


Kind regard