RPM X pitch...... divide gear raito...... divide 1050 X slip = speed
EG......... 11000 X 24 = 264000.00 divide 1.87 =141176.47 divide 1050 =134.46 X .90 = 121.02 MPH.
.90 is 10% slip .95 is 5% slip and so on.
You Te
dose any one know how to figure speed with pitch to RPM
I have a 89 242Eliminator edge with a 24 pitch bravo 1 4 blade
turning 5100 rpm
thank Shawn
RPM X pitch...... divide gear raito...... divide 1050 X slip = speed
EG......... 11000 X 24 = 264000.00 divide 1.87 =141176.47 divide 1050 =134.46 X .90 = 121.02 MPH.
.90 is 10% slip .95 is 5% slip and so on.
You Te
Prop pitch X RPM
divided by
gear ratio X 1056
this will give you your theoretical speed
take your actual speed and divide that by theoreticle speed and that will give you a number like .89 for example which would indicate 89% efficiency or 11% inefficiency (slippage).
here.
prop calculator (http://www.hillpropellers.com/propcalc.html)
I think this one is easier.
RPM X PITCH X GEAR RATIO X SLIP X .0009469 = SPEED
6,000 X 15 1/2 X 1.18 (18'S IN A V DRIVE) X .85 (15% SLIP) X
.0009469 =85.48
Sounds about right for a nice flattie, not a hydro.
Works for Mercruiser, only the gear will be .25, .50, .65, etc.
I always liked the following:
rpm x pitch x ratio* x .00094697 = theoretical speed. Then you have to find your slip factor and multiply it in. 10% is super, 25% for sleds.
*a V drive usually give you overdrive, but all stern drives are under driven.
A radar gun or GPS will pretty well peg your slip factor...
thanks every one now i need a gps