Prop Selection

I am pushing a big heavy boat with a relatively small engine. I am not concerned with speed. Is it better to buy a low pitched prop or a high pitch prop.

Thanks

 

Depends on the prime mover and gearing. In general for equal horsepower, low pitch requires less torque, more RPM; high pitch require low RPM, more torque. However there a limit as to how low or high a pitch you can go on a given diameter : hp combination and still have effective thrust.

More info (hull type, lwl, hp, max diameter) would make for a clearer picture.

 

Some of the engine manufacturers have prop size calculators on their web sites. You just have to fill in the blanks and press the button. Nannidiesel is one of these and I'm sure you can find more by searching.

 

I am pushing a big heavy boat with a relatively small engine.

To get the best from a small engine the pitch should let the engine run at the MFG top rated rpm (just as a test) and then be pulled back by at least 10% of that top RPM.

A cruise at 75% of rated rpm should cost little in speed and will allow the engine about the longest life.

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