Can somone figure this out for me
21 ft elim open bow
4850rpm 59mph(gps)max(good condtions) avgs 57@4800 mostly
aplha drive 1.50 gear
21 pitch 3 blade stnls
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Can somone figure this out for me
21 ft elim open bow
4850rpm 59mph(gps)max(good condtions) avgs 57@4800 mostly
aplha drive 1.50 gear
21 pitch 3 blade stnls
Hmmmmmmmmmm Faster than me :( Sorry I can't Help.Don't mind me I'm just trying to Build up my Post Count :D
Steve
Hi!
4850rpm 59mph(gps)max(good condtions) avgs 57@4800 mostly
aplha drive 1.50 gear
21 pitch 3 blade stnls
4850 x 21 / 1056 / 1.5 = teoretical speed = 64,3 mph. Slip approx. 9% which is very very good.
Cheers, Toffen G
thanks toffen.What is the range considered good Ex 0-12%
10% is good for a V-hull...cats can be a little better...
After running a prop slip calculation with your set up you are right on target. If you pitch it up you will drop the rpm down and loose MPH. Tested a 19 ft boat with a very flat v bottom with a 350 merc cruiser, alph 1 drive, 21Px13 3/4 prop. It ran at 4800 rpm @ 60.1 MPH. The boat weight was 2400#.
This will work to figure any of the variables.
http://www.boatpropellers.com/propcalc.html
I came up with the same slip%. Setup looks pretty good. Cats with higher x-dimensions tend to have the slip numbers improve at higher speeds. If running a labbed prop in the midrange the slip will be worse. The ***boat article with the twin engine eliminator cats with varying setup, standoff and props showed that very well.