I am wondering if the calculation we are presently using is correct.
Are these GPS speeds believable?
I ran a Bravo 26, just reconditioned by ThrottleUp, and was seeing, on GPS, 82.7@5600 rpm.
This is a 1989 27' Activator with a 1.5/XR/IMCO -2 Shortie drive, 5.25" propshaft to keel dimension.
I questioned the pitch number back to Julie and she said that they put it back to stock, which is a measured 25" of pitch for a Bravo 26. She thought my tach could be off.
I have yet to confirm it's accuracy.
If you crunch the numbers and use 26 for the pitch, it calculates out to 10% slip. At this point, it's anyones guess.
Russ

Can I borrow YOUR gps??

Those are incredible numbers.

lets say that the water down stream was 4 mph.... so this puts me at 90 mph.... this could account for the really low slip numbers. i have also had it at 70 with 7 people in it and the rpms were much higher like 5400 (closer to 20% slip) but i did not feel comfortable with that many people in the boat going fast. Once again i do not know how the guys with the big cigs and cats do it? so it is possible for the prop be more to a 28 that a 27 as stated. but if you shave some off the leading edge to increase rpm..... Hell i do not know.... i should just drop the boat off at Bblades in Princeton, and have him work me up a prop. This prop slip thing is interesting. so much technology in a prop.

This prop slip thing is fun but to really dial it in i have to get the steering. and other things. i think i will just let it go for this year and enjoy the boat. it goes too fast to dial it with the equipment that i have and i do not want to hurt my self or any one else. How much for a prop recondition and dial in? this 27 that i have seems close to what will work.

what online prop calculators are there out there?
I was using bams go fast knowlege base one. Do they all go off of the same figures?