• Welcome to the Checkmate Community Forums forums.

    You are currently viewing our boards as a guest which gives you limited access to view most discussions, articles and access to our other FREE features.
    By joining our free community you will be able to:

    » Interact with over 10,000 Checkmate Fanatics from around the world!
    » Post topics and messages
    » Post and view photos
    » Communicate privately with other members
    » Access our extensive gallery of old Checkmate brochures located in our Media Gallery
    » Browse the various pictures in our Checkmate photo gallery

    Registration is fast, simple and absolutely free so please, join our community today!

    If you have any problems with the registration process or your account login, please contact support by clicking here or by using the"contact us" link at the bottom of the page.

250 ProXS on a V-Mate II

kalugs22

kalugs22

Well-known member
We sold Dad's Hydrostream Voyager Hull and Trailer so he can get back into a Checkmate next summer. We kept the 2007 250 ProXS that came on the boat. So I only found it fitting that i run it on my V-Mate II before putting it away for the winter :)

Took it out today for some fun, it's quite a ride and that boat handles the motor quite well. I ran the 27p Trophy today but I'm going to run the 28p Merc Racing Trophy tomorrow just to see the difference. I had it up to 87mph today by myself and I still had some left to go, I cruised up the river back to the ramp with my buddy at 85mph. No chine walk at all and honestly I'm more comfortable going over 80 in that v-mate than I ever was in his hydrostream. We took some videos today but dad has them, I'll post them tomorrow but here's a couple pics for now.

After the swap...
8EAE0637-orig.jpg

Beach Pic...
3A0C0BFF-orig.jpg

Dad out for a speed run...
55611766-orig.jpg
 
With a 1.75 gear, that comes out to negative 9% slip. You must be looking at a non GPS speedo. At the normal 10% slip, you are running 72-73 mph. You need to take a handheld GPS with you.
 
WILDMAN said:
With a 1.75 gear, that comes out to negative 9% slip. You must be looking at a non GPS speedo. At the normal 10% slip, you are running 72-73 mph. You need to take a handheld GPS with you.
Click to expand...

I did have a handheld GPS with me that I checked with the truck on the way home and is spot on, I'll check the RPM tomorrow when I take it out again I might not have been really paying that much attention to the tach as I was focusing on driving and the GPS.

The 27p trophy I'm running has also been labbed and has an extremely sharp cup with alot of bite. I ran it on my predictor at 82mph 6100rpm 2.4 200 with a 1.87 gear case and had 1-2% slip. my boat weights around 700lbs, there's not much there to carry, plus I have that motor jacked up as far as a possible.

Actually I saw the same results with that motor and prop on the hydrostream voyager it came on.

The other motor I have been running on the v-mate is a 2.4 200 with a 1.87 gear case turning a ron hill 26p chopper at 6300-6400 running 82mph @ 1-2% slip. That boat gets out of the water and doesn't have any drag. I don't have average slip I never have and actually I can back up my slip with my fuel economy considering today I probably averaged 6-7mpg and I typically do 4-5 with my 2.4.
 
Last edited:
I don't know what slip calculator your using, but I'm using Merc's considering the motor and prop are both Merc.

Here's my results...and like i said that prop has been labbed for more bite (I had one that wasn't labbed and you could tell the difference)

Screenshot2011-10-09at125431AM.png
 
Well, 1% slip is impossible. I've been doing this a long time and 9-10% is good, and the best I've seen is in one of the tunnel boats I sell and that was 7%. And that was at a GPSed 128.4 mph with twin 315hp 2.5 Mercs turning 8450rpm with 32" props on my 21 Liberator.
Here's the formula I use. .000946 x .57 (1.75 gears) x 5600 rpm x 27 (prop) = 81.53 mph with no slip. If you take off 10% slip, 81.53 x .9 = 73.38 mph with 10% slip.

When I ran my 21 Pulsare with a 300xs and a 1.62 sportmaster, It checked out this way.
.000946 x .62 (1.62 gears) x 6400 (on the limiter) x 28" prop = 105.1 mph x .9 = 94.6 mph.
My GPS speed was 96.3. If you take the 105.1 and divide by 100, each percent is 1.051. Take the 105.1 and minus the 96.3 actual speed, you get 8.8. Divide that by the 1.051 and you get 8.37 which is the percentage of actual slip. A boat usually has to get close to 100mph before the slip goes much under 10%.
So anyway, at least one of your figuers has to be incorrect. If you run the boat with a GPS in it and your tach is correct, you will probably come out about 10% slip.
 
Randy, I'll bet his heavily modified 27" prop is closer to 30" pitch now. Maybe even more
 
The #s don't add up but a 700#/ 17' boat with 250 hp is going to run faster then 72-73 mph. What rpm should a 250XS run at WOT?
 
Boat looks great, I cant imagine how it handles with that motor. Keep us posted.

I dont really feel all the posts about it not adding up are needed.
 
Last edited:
Awesome looking setup kalugs22, that motor looks sick on there!!:bigthumb:
Great East Predictor said:
Motor looks sweet on there :thumb:

For what it's worth I spin a 27 trophy, 1.87 gears, on the rev limiter at 6850, gps speed of 91 mph which works out to 3% slip.
Click to expand...
3% slip and yours is proven with video and GPS.... Guess others ain't as good as they think with their wonderful "all off the shelf" bolt on setups!

TheNerd said:
I dont really feel all the posts about it not adding up are needed.
Click to expand...
X2!
 
Good looking boat! Blue and Silver Metal flake is my FAV! The 250 hangin on back don't hurt either ;)
 
Ok, for all of you who don't think anyone should post about the numbers not adding up, this site is suppose to be helpful. No one is slamming anyone, but it could be helpful to someone down the road who is trying to figure out why his Checkmark with a 21" prop is not running 92mph with 1% slip. We all no how accurate a GPS is for checking speed, but that doesn't mean the tachometer is right. I have had false reading myself. I hope this boat runs 100. But I would also like to know how to get 1% slip. I also hate this touch pad that will not let me write what I want! Checkmark Checkmark Checkmark See what I mean!
 
I think the rpm or the pitch numbers maybe off. The speed is very doable tho. We don't race slip numbers, only speed numbers. Dream-o-meters don't count, only GPS or Radar. Its easier to get lower slip numbers with a tiny light hull
 
You must log in or register to reply here.
Back
Top