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gnarley
01-23-2003, 04:12 PM
I am about to upgrade to another prop better suited to my hull & wondered what anyone else is getting for slip #'s with an offshore style V hull and a single prop? What size hull & weight & prop & slip?
Thanks

rivercrazy
01-23-2003, 04:18 PM
I'm seeing about 7% slip with a 4,100-4,300 pound hull. The prop is a bone stock Merc 23 pitch Revolution-4 four blade
[ January 23, 2003, 04:53 PM: Message edited by: rivercrazy ]

gnarley
01-23-2003, 10:41 PM
rivercrazy:
I'm seeing about 7% slip with a 4,100-4,300 pound hull. The prop is a bone stock Merc 23 pitch Revolution-4 four blade And what for HP? to help put into perspective.

rivercrazy
01-24-2003, 08:43 AM
496 Mag HO.
So far on GPS the best I've seen is a shade over 70 but for the most part I'm seeing 68.5 to 69.5 depending on the conditions. These are all GPS'd speeds using a Garmin III+ GPS. Best speed has been in about 1 foot chop and temps in the mid 60's. That's in a 25' Shockwave.
I still cannot believe how well this stock prop works on this boat. :D
[ January 24, 2003, 08:44 AM: Message edited by: rivercrazy ]

gnarley
01-24-2003, 09:51 AM
RC what's the Horse Power for the 496 Mag HO? I think I read it was like 375 or 425 but I don't know for sure.

rivercrazy
01-24-2003, 09:53 AM
425

Skaterfast
01-27-2003, 07:29 AM
rivercrazy:
425 How are you calculating your slip?Seven percent in a 4200lb v bottom is almost not beleivable.Some cats don't even get 7%.I'm impressed if it's true.

rivercrazy
01-28-2003, 09:49 AM
I'm not sure if this prop slip calculator is totally accurate or if I botched entering in the figures and got a bogus result.
http://www.go-fast.com/Prop_Slip_Calculator.htm
I'm running 1.5 gears, a 23P 4 blade Rev-4 at 5050rpm and getting 68-70mph on GPS (depending on conditions).

Toffen
01-28-2003, 02:24 PM
Hi!
The true pitch can be different that the stamped one. Normally you should add one pitch using high rake props or cupped props. If adding one pitch you should be closer to 10% slip, which is very good for that kind of v hull.
Cheers, Toffen G

rivercrazy
01-28-2003, 02:40 PM
Thanks for the clarification. So what your saying is that I'm really closer to running a 24 pitch prop for prop slip calc purposes right?
That does sound more reasonable to me. I did always wonder if the slip numbers I'm getting based on the GPS'd speeds were bonefide. :D

gnarley
01-28-2003, 04:17 PM
I think what he's sayin is even though your's says 23 it may not be & with that # you have of 7% it isn't likely just a 23P prop, so if it is cupped you can add about another 1 degree to the pitch in theory making it a 24. So if you have a true 23 & its cupped it works like a 24 that would give you 10% still a great #! And if it was ever reworked by anyone it could be a cupped 24 that works like a 25 & gives 13% which I think sounds more like it and is a good number also IMHO

rivercrazy
01-28-2003, 04:22 PM
Actually to prop is box stock but it does have some pretty good amount of cupping on the ends of the blades.

Trash
01-30-2003, 10:15 PM
Skaterfast:
rivercrazy:
425 How are you calculating your slip?Seven percent in a 4200lb v bottom is almost not beleivable.Some cats don't even get 7%.I'm impressed if it's true. The Rev 4 has a lot of blade area, and depending on how deep the drive is set, 7% is not all that unreasonable. Most cats I've that I've calculated have much higher slip numbers, mostly due to labbed props and high x-dimensions.

rivercrazy
02-02-2003, 05:17 PM
I really like the Rev-4 on this boat. The X dimension is pretty typical on a deep V. The anti cav plate runs just above the water on plane.