I Need a Propeller

[valentingrosu]

hello. i"m the new guy.
I want to exchange old gasoline engine with a diesel-engine of 10 horsepower Farymann. I bought the engine without propeller. now looking for a propeller to match the boat size and engine power. My boat dimensions are 18 ft long, 6 ft wide, 2.5 ft draft. I want some advice about propeller pitch and diameter that would fit my boat and engine

[shakey doug]

G'day,
More info required. Engine; 1. max rpm. 2. horse power at max torque rpm or cruising rpm. 3. max torque rpm or torque at cruising rpm, 4. gearbox reduction. Boat; 1.water line length. 2. hull type, keel type. 3. type of prop required. 4.hull material.You will need to keep in mind the rotation direction, post what you know of the previous points and we will give it a shot.

Cheers, Shakey.

[osirissail]

Or - just look around and see what size everybody else is using for your size boat and engine hp. Then find a propeller shop that sells used propellers and find one of about the same size and put it on the boat. Try the boat checking for ability to achieve hull speed; ability to achieve max rated rpms; and whether the engine is lugging/smoking at cruise to max speed. Then exchange the propeller for others one size up or down (pitch or diameter) until you find one that allows you to get hull speed at less than full rated rpms and without smoking. It is a crude system but works if you have the time and can find a friendly prop shop.
- - If you can get a calculated prop size, that would be your starting point versus just asking or looking around. You still need to test the recommended prop for the aspects mentioned above.