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1997 Dauntless 70 hp 4 stroke 500 lbs on board weight, boat used for recreation fishing in bay area. Just purchased new engine and need prop selection advice. Based on reading previous posts, an 19" prop is the correct size, but not sure the correct pitch. Appreciate your assistance.
You might want to mention what motor you have just purchased. While you're at it, let us know the WOT range and the gear ratio as well. Nobody can offer advice on an appropriate propeller without that information.
It always helps to put the size of the Whaler in your post. 13', 15', 17', etc.
And also the brand of motor. Yamaha, Mercury, Evinrude, etc.
That way others can help you more readily and easily.
I have a 1997 15' Dauntless with a new 70 hp Yamaha 4 stroke engine that has full throttle operating range of 5000-6300.
Thanks again for your assistance.
The Yamaha F70 actually has a 5300-6300 WOT RPM range. It also has a 2.33:1 gear ratio. This information can be found in your Owner's Manual.
Based on reading previous posts, a 19" prop is the correct size, but not sure the correct pitch
.
19" would be the pitch; it can't be the diameter because there is no outboard made that can swing a 19" diameter prop.
At any rate, there is no such thing as a "correct" propeller for a given boat/motor combination, just one that may work better for a given application.
Propellers are not generic pieces of hardware where all you need to think about it pitch and diameter. Every model of propeller will have its own characteristics that allow it to do something better than others. Once you choose a particular model of propeller, *then* you need to figure out what pitch is appropriate.
In the case of a Yamaha F70 on a Dauntless 15, the choices are greatly reduced so it is not a difficult porcess.
This boat should be good for about 40 MPH. Given the gear ratio and engine speed, I recommend a 13-1/4" x 15" Stiletto Advantage (or Turbo 1) 4.25
You could also use a 13-1/2" x 16" or 13" x 17" Yamaha Painted Stainless Steel.
The 14" x 15" Yamaha Pontoon Performance Series might be a good choice too.
Just be sure the motor is mounted as high as it can go on the transom with the mounting bolts going through this hole in the motor's mounting bracket:
