prop slip
 

I've seen the Bam site for figuring prop slip...
my question is how do you reduce it??
thanx
mike

what set up are you running now? give us a little info: and we can give some input, every boat is different and so are props, tell us more.

Changing props or changing drive height is the most common way to reduce slip.

Ok....
'03 280 silencer 496 ho
bravo 1 x with 1.50
labbed 26 bravo 1
w.o.t 4900rpm
speed is 64-65 mph? - I may need to recheck- will do this weekend

thankx,
mike

yep...confirmed speed was 64 mph, 4900rpm, bravo 1 labbed, 1.5 xr drive, 496 ho

Bravo I props are not true pitched. I have been told that typically for a 26 pitch that you should use a pitch number of 25.3. Doing that your slip factor is 18%. I believe anything over 15% is considered high. I am assuming that you are using a gps speedometer. Anything other than gps is a best guess. This is the formula that I used.

4900 (rpms) X 25.3 (pitch) divided by 1.5 (ratio) divided by 1056 (factor) = 78.264 X 82% (slip) = 64.176 mph.

I just spent an entire day testing props I was able to borrow......5 blade maximus got me as low as 10.9% at 4,000 and at WOT it was 11.X (can't remember)!!!!!



Looks like I'm buying anopther set of props!!! (My bravos came in at almost 19%!!!!!)

Holly....how long do I need to keep scratching my head???
And yes with the gps speed...
Thankx guys....
mike

So with too high a pitch what is the next step?????

Take your prop to a prop shop and tell them what you want to achieve.

Will do...thanks for the input.

mike

I have a 25' Switzer. 454 Mag carburated Bravo 1. It has IMCO Thumper Power exhaust manifolds. I figure it is putting out 385hp. With a 23p Mirage at 5000rpm and 1.5-1 gearing it runs somewhere in the 60-62mph range and that works out to a 17%-15% of prop slip. Is that the best I should get out of this set-up or can I get somemore by playing with trim or going to a 22p Bravo 1?

call Brett at BBLADDES I think you would do better with a rev 4 23 p rwe worked by him. they have a test prop program.:cool: