Formula

[LUVNLIFE]

Hey can I get the formula for calculating mph, horspower, propsize,rpm with slip deal. Thanks in advance guys. Cale

[bigkatboat]

I can tell you about the prop speed +- slip equation. Engine RPM divided (or multiplied) by gear ratio. Times prop pitch, divided by 12". That number times 60, divided by 5280 = prop speed +- slip. I/O's example; 5000 RPMs, divided by 1.50 = 3333.33... 3333.33 X 24 (pitch) = 79999.99. 79999.9 divided by 12" = 6666.6 6666.6 X 60 = 399999.9 . 399999.9 divided by 5280 = 75.757 (prop speed) Example 75.757 X .90 = 68.18 MPH (good boat speed @ 10% slip) V- drive (overdriven boats) can have many variables as to top speed. (wet VS flying) 6500 RPMs, X 1.29 (gear ratio) = 8385. 8385 X 16 (pitch) = 134160. 134160. divided by 12" = 11180. 11180 X 60 = 670800. 670800 divided by 5280 = 127.045 (prop speed) 127.045 X .80 = 101.636 MPH How fast do you really go?

[Tahiti350]

Try this link: http://www.admboatworks.com/pitch.htm
They have a cool calculator right on the website. Haven't GPS'd mine yet, but believe it accurate, as long as your slip percentage is close.

[LUVNLIFE]

Thanks for the info guys. Cale