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View Full Version : Do I need a shorty?



The Hedgehog
05-30-2006, 05:32 PM
I have a 27ZX non-step with a Procharged 502 MPI running at 5lbs. I had the opportunity to check out my drive while running at 65mph. We had 3 on board and about 1/3 tank of fuel. My cavitation plate was buried!

I am no expert on X-dimension etc but it sounds like I am getting a bunch of drag. Has anyone run one of these on a 27ZX non-step? My shaft depth is currently around 8" below the V.

Last Real Texan
05-31-2006, 02:58 PM
Tough question...................The jury is still out on my twin step on this matter. The shorty seemed to help a bunch with a box stock prop but labbed it was too much slip. I as you know have installed a 1 inch spacer that has helped with the labbed prop I have, but it is still not as fast as with a stock prop and no spacer .......go figure. I am thinking about going to a 5 balded prop with no spacer and testing the results..............of course the easiest way to gain speed for me now is mo power but I am still in the justification phase of that Vortec hair dryer.

I still know this does not answer your question but I think at the least bring it up an inch. We still need to put the shorty on you boat and give it a try. I am suprised no one has chimed in on this thread yet.

Bryan

mrfixxall
05-31-2006, 03:17 PM
I have a 27ZX non-step with a Procharged 502 MPI running at 5lbs. I had the opportunity to check out my drive while running at 65mph. We had 3 on board and about 1/3 tank of fuel. My cavitation plate was buried!
I am no expert on X-dimension etc but it sounds like I am getting a bunch of drag. Has anyone run one of these on a 27ZX non-step? My shaft depth is currently around 8" below the V.

Are you running a 3 blade or a four blade prop?

The Hedgehog
05-31-2006, 06:06 PM
4 blade Lab-finished Bravo I with some extra cup. I got my prop from Throttle-up.

blackhawk
05-31-2006, 06:33 PM
How would using a shortie raise your anti-ventilation plate? Wouldn't you have to raise the actual X-dimension?

BigGrizzly
05-31-2006, 08:24 PM
Big Green, what is yoiur goal. when out of the water where is your cav plat in relation to the hull when they are paralell to each other. The bravo1 would be my last choice when i go to Eufaula I will bring some props to test

The Hedgehog
05-31-2006, 10:03 PM
How would using a shortie raise your anti-ventilation plate? Wouldn't you have to raise the actual X-dimension?

Actually I am not worried about the plate as I am concerned the actual depth. When I see pics on Powerboat, Hotboat etc. all cavitation plates are even with or slightly above the surface.

Yes, A shorty would eliminate that. They scrap the plate and bring the shaft height up.

The Hedgehog
05-31-2006, 10:22 PM
Big Green, what is yoiur goal. when out of the water where is your cav plat in relation to the hull when they are paralell to each other. The bravo1 would be my last choice when i go to Eufaula I will bring some props to test

My goal is to find the optimum shaft depth. I tested a number of props but would still love to test some more. I tried a number of Bravo's and Mirages. The 3 blade did not seem to like the torque of the 502. I tried a number of props and conditions. I spun a 25" Mirage plus at 21% slip at 65 mph on the rev limiter.

The funny thing is that right before my labbed 26 came in, I actually got my worn old 23" Mirage Plus to hit a run at 65 mph. The boat mystically lifted up and ran at 12-13% slip. I was bouncing hard on the rev limiter so I backed off. I have played with so many trim and water combo's but have never been able to duplicate those slip levels. I can pull 18-19% slip on the Bravo but it still feels high and did not lift like that one day.

I still think that I have more to do. The cav plate is about 7.5" - 8" at parallel. I will try to get the exact dim tomorrow.

I would appreciate your input and look forward to meeting you at Eufaula. Please bring props. Tex has a Shorty that I will try but I was wondering if anyone else had tried one.

I also look forward to seeing your machine. I would love a ride in that boat.