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mikev
10-11-2001, 09:21 AM
I punched my numbers into one of the prop calculators and it said my slip was 14.5% does that sound about right. i have an old SS 3 blade prop on a 19' V6 bowrider.

Formula Jr
10-11-2001, 05:56 PM
Its alittle high but you have alot of wind resistance with a bowrider and windshield. And 14% is in the ball park if the boat is alittle underpowered or overweight. Also if you have meticuliously polished and waxed your bottom, it will be more sticky. How did you get your numbers. Using tabs incorrectly will also drive up the slip as will trimming the drive up to far.
Older SS props tended not to have hub inserts so hub slipping should not be a problem.
I'm happy at 8% slip with the standard Merc three blade 21s. I hit too much stuff to risk SS props. The manual formula for Ideal speed is
((WOT RPM/Drive Ratio)X prop pitch)/1056 you then compare this MPH with observed MPH -timed course or GPS with no current - to find the slip. I've never seen a formula that takes into account Prop Rake. The conditions for the observed run should best match your hull. Deep Vees run faster airing out in a slight chop.

The Classic Razorback
10-11-2001, 07:00 PM
How dose the hub slip?

Owen what do you think
about stocks GX and XOXO ?
Chris

Gearhead99
10-11-2001, 07:41 PM
The slip they are talking about is the amount of slip the prop experiences in the water vs a solid material.

Not a hub slip. But, a slip in the water enviorment. Like a torque convertor.

mikev
10-12-2001, 08:22 AM
I do not have tabs but the boat is a little underpowered V6 175hp 2brl. i got the speed from the speedo is i know it isnt 100% accurate. the HP upgrades and new prop I am planning for this winter hopefully i will get less slip as well as more power.

Formula Jr
10-12-2001, 08:31 AM
Using a water pressure speedo is a waste of time. They just give you something entertaining to look at and tend to move up and down when you go faster or slower. But they don't tell you what your speed is. :)

falcon
10-13-2001, 02:41 AM
does anybody have web address for slip calculation--i used to have one but it was deleted when i got a virus.

Craig
10-15-2001, 11:30 AM
I must've just got lucky. My 1970(+-) Teleflex speedo matches GPS exactly. No Kidding!

Craig
10-15-2001, 11:33 AM
...that is to say, when I'm sitting still, they both read "zero"!!!! Just kidding, they really do match.

doug hess
10-16-2001, 12:28 AM
Prop calculators are at Boatramp, hillpropellers and go-fast dot com's