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View Full Version : Tested a new Prop and



buzzaro
09-18-2006, 02:09 PM
it didnt work worth a crap on my boat. 23' w/ 454 mag mpi currently running a 24p bravo 1. I was looking for something with more of a hole shot for towing toys or people with a full boat. We tried a mercury hi-5 23p. I was really surprised that it cavitated around 3500rpm and out of the hole wasnt much better. It did accelerate harder when I took it easy and didnt blow it out but lost a ton of top end 12-15mph roughly. I didnt expect a night/day difference givin the 1p difference and certainly didnt expect any problems hooking up going from a 4blade to 5blade. I guess you just never know with props and gotta try em all.

bocco
09-18-2006, 02:50 PM
Just questions to think about. Do you have a bravo drive? Is the prop for Alphas? I would go up in pitch with a high five. I had one on a smaller boat with an Alpha and loved it.

buzzaro
09-18-2006, 03:02 PM
Just questions to think about. Do you have a bravo drive? Is the prop for Alphas? I would go up in pitch with a high five. I had one on a smaller boat with an Alpha and loved it.
Yes, bravo1 drive. The prop we tested was the only one my father-in-law had in the shop that was even close to what might work so we gave it shot. I am not sure what the hi-5 was designed for, I am not trying to say the hi-5 is a crappy prop but that one definately didnt work on my boat and i couldnt believe how much of a change it made. In fact, he (F-I-L) has one on his 21' Elim and loves it as well.

BajaMike
09-18-2006, 03:03 PM
I would try a 4 blade 22 pitch....
:idea:

boatnam2
09-18-2006, 03:03 PM
what kind of boat?i had a 21ft ultra and the high five seemed to work the best on it,i think it was a 21p but only a 350mag.

buzzaro
09-18-2006, 03:06 PM
what kind of boat?i had a 21ft ultra and the high five seemed to work the best on it,i think it was a 21p but only a 350mag.
Boat in my sig, 23' cobra

boatnam2
09-18-2006, 03:06 PM
buddy just bought a warlock 23ft with 496 he is running a 26p 3 blade and it seems to pull good and run pretty decent on top end 68mph or so.

boatnam2
09-18-2006, 03:07 PM
sorry i have my sigs turned of at work.

boatnam2
09-18-2006, 03:08 PM
i would call jeff and ask him what he recommends and go borrow a couple of props from a shop,it could make a big difference or maybe not.usally mfg has just about the right all around prop put on.

SnakeWrench
09-18-2006, 07:27 PM
Hi 5 will not work on that boat. Use a 22 4 bld Bravo or a 21 5 blade Maximus style. No reason the 22 4 won't work. Is the skeg damaged at all? Reason I ask, we had one not long ago that blew out real bad, and after cleaning up the front edge of the skeg, it worked fine after that.
One other thing, make sure the prop shaft is straight. A slight tweek in the shaft can produce instant cavitation.
If you have any questions, call me at the shop.
Jay
www.cobraperformanceboats.com

OCMerrill
09-18-2006, 07:44 PM
I had a high 5 21p on our boat. Last trip I tried a freinds 21 pitch "Turbo" three blade and the boat was night and day different. More bow lift and about 6 mph faster. All gps verified. I was amazed. I bought this boat with the high 5 on it. Now its going on Ebay.
So I hunt for a three blade. My boat is a runner bottom though.
The reason I tried another was the dam thing kept blowing out and cavitating around the same RPM you describe 3500 to 4k with the drive trimmed.
With the 3 blade I can trim the drive 20% more and no cavitation at all.
My thory is this...Small blade x5 gives alot of stern lift...drives my bow down and cannot hold trim, again small blade area I guess. I dont need stern lift I need bow lift and the difference was dramatic going to the three blade.

buzzaro
09-18-2006, 07:53 PM
Hi 5 will not work on that boat. Use a 22 4 bld Bravo or a 21 5 blade Maximus style. No reason the 22 4 won't work. Is the skeg damaged at all? Reason I ask, we had one not long ago that blew out real bad, and after cleaning up the front edge of the skeg, it worked fine after that.
One other thing, make sure the prop shaft is straight. A slight tweek in the shaft can produce instant cavitation.
If you have any questions, call me at the shop.
Jay
www.cobraperformanceboats.com
If the skeg is damaged was it blowing out on all props? Same with the prop shaft? Because the thing runs like a champ with the 24p 4-blade on it.

buzzaro
09-18-2006, 07:54 PM
I had a high 5 21p on our boat. Last trip I tried a freinds 21 pitch "Turbo" three blade and the boat was night and day different. More bow lift and about 6 mph faster. All gps verified. I was amazed. I bought this boat with the high 5 on it. Now its going on Ebay.
So I hunt for a three blade. My boat is a runner bottom though.
The reason I tried another was the dam thing kept blowing out and cavitating around the same RPM you describe 3500 to 4k with the drive trimmed.
With the 3 blade I can trim the drive 20% more and no cavitation at all.
My thory is this...Small blade x5 gives alot of stern lift...drives my bow down and cannot hold trim, again small blade area I guess. I dont need stern lift I need bow lift and the difference was dramatic going to the three blade.
Yes, it was SUPER sensitive to any trim at all w/ the hi-5. It was all the way down or nothing.

BadKachina
09-18-2006, 09:18 PM
The high five is more of a small boat or outboard motor boat application. The diameter is from 12 3/4 to 13 1/2 inches. A Maximus has a diameter of 15 to 15 3/4 inches. That's why you are blowing it out, it wasn't designed for a boat your size. Try a 22 pitch Bravo one first or maybe have some lab work done to your 24 pitch. You should be able to get some more midrange/holeshot out of the prop you have with some tweaking.