Which prop?
 

Hi guys. I have an 88 checkmate convincor 25ft. I am in the process of putting in a 435hp 502 efi. Wondering what prop would be good. I had a 330hp 454 previously with a 23p three blade. Obviously want a good balance of speed and getting out of the hole. Any suggestions would be great. 3 or 4 blade??

24P Bravo 1 which is a 4 blade would probably work good all around. I would put that 23 on and see how it runs first and see how many rpm it will spin at WOT. That will give you a starting point. What 23 is it? How many RPM would the 330 turn at WOT with it.

Pete can we assume a 1:50 ratio? I had a 88 convincer myself, 1:33 gears, 26 pitch three blade outboard cleaver, 4" shorty, 454/650HP ran 101 with 9% slip stable as could be. You hull will handle the speed, with the right set up.

Do you have merc K planes?

also be carefull on the 4 blade might give you to much stern lift with a deep X dim, stern lift is not good for that hull it will be unsafe!

Thank you for quick replies! The 23p was a mercury mirage. Yes I do have short trim tabs. I believe that I would turn about 4600 with the 330 in it. I see some good deals on used 25p 3 blade mirage props. Not sure if that would be too much. Yes I have bravo drive with 1.5:1 I'm 99% sure. And here's another thing, don't want to ask a stupid question but obviously my motor is a lh engine and my prop that I looked up says rh turn. So that would make sense I need a rh prop? Thanks again for input

yes Rh prop 99% of the motors turn rh looking fom thr front so when looking at the crank it rotates correctly in a counter clock direction. I would start with the 25 three blade, record all the stats, fuel level, #passangers, water conditions, RPM, and speed. keep a book for reference, so you can make decisions based on facts. JMO.

Ok great advice. The cleaver prop you used was solid hub? Good or bad idea on my bravo drive? Anything I would need to change on the drive? Stick with 14.5 diameter or so? Sorry for so many questions. I appreciate the help. Pete

The cleaver was a solid hub, but that will not work at all for you unless the X is raised a lot, they are surfacing props, absolutly go with 14.5 dia props remember the faster you can spin the prop the better. your boat will suffer with a bigger dia wheel. how many RPM max do you want to turn?

I know the engine is assemblied well, but is mostly stock. I don't want to beat the hell out of it. I was thinking between 4800-5000 wot?? What do you think. Want it to stay reliable for a long time.

5000 sounds safe, if you can spin the 25 to 5000 with 12% slip you can see 70 MPH, once you get your test data, contact merc, bblades, cutting edge, etc, for fine tunning. keep us posted!!

I appreciate the help! Pete