Boat Speed and Prop Slip calculators

Post by **DaleH** » 23 Mar 2017, 14:33

Here are a boat speed and prop slip calculator if anyone is interested:

Theoretical Hull Speed = ( Prop Pitch X RPM ) / ( LU Gear Ratio X Constant of 1056 )

Prop Slip = ( Theo. Speed - Actual Speed ) / ( Theo. Speed )

I have found the speed one pretty accurate with small open v-hull skiffs. But where a lot of your guys' boats have extensive flooring, decking, and compartments ... I'd expect lower actual speeds due to the actual weight carried. Also note a jon boat will have more wetted surface on the running hull and will be slower.

flex · Post by **flex** » 23 Mar 2017, 14:38

Thanks man. I'll try and figure it out. Going to raise the motor up a bit and play with trim this weekend. I just figure I had a fiberglass glasstream bass boat years ago with a 70 that ran 42. This boat weighs half as much it should scoot! Hopefully I can get it dialed. I'll post up as I experiment. Hopefully put a tach on soon as well.

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Crazyboat · Post by **Crazyboat** » 23 Mar 2017, 16:14

Knowing ones LU gear ration is key to this.

Stumpalump · Post by **Stumpalump** » 04 Jun 2017, 21:01

Good calculator here:

https://www.mercuryracing.com/prop-slip-calculator/

andrewwty · Post by **andrewwty** » 21 Dec 2020, 07:12

Thanks For the formula. but i don't fully understand how to use it correctly for calculations