which prop to use?

[ckeebler]

how do you know which prop to use,when building a boat?.40and .21 size engines in hydros.is like gearing your rear end for 1/4 mile,and 1/8 mile?how exactly does all that work?

 

[Climate Boatworks]

The correct prop will be the one that lets the motor unload at the best working RPM, (horsepower) and is still big enough to push the boat through the water.

There is a general guideline of what prop to use with what set up on most prop manufacturers data sheets, but even identical boats can be a bit different and run better on one prop or another.

There are 2 basic things to think about when choosing a prop, Pitch and Diameter.

Pitch is the theoretical distance the prop will travel forward in one full rotation in the absence of any slip.

Diameter is the overall size of the prop.

If you want top end speed, a high pitched prop is the answer. Hole shot and acceleration are best with a fine pitch prop. The top end will be slower though.

Peter

www.climatemodels.com

(Maker of the fastest production rigger kits in the world)

 

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For the .21 you can go with a 447 or 440, or try 215's and 220's up to 225'S.

For the .45 try a 450, 452 or 455. I've got a cut down 457 on my hydro.

 

[user 115]

For 21 hydro try 1450 or H-7.

45 Hydro - 1457 or 1657