need some prop help
 

the boat is a 259 checkmate with 7.4 385hp went from a 23p 3 blade mirage plus to a 24p 4 blade hydro that has been slightly labbed. boat would turn 5000 rpms with the mirage and sometimes hit the rev limiter with light load cool day slight chop. with the hydro the ride is GREATLY improved but can only pull 4400 rpm with light load chop 80degree day. i know i should of went down on pitch but got a good deal and figured i could get this one worked. big problem is having hard time planing with four blade but never had a problem with the 3 blade, doesnt seem to have enuff grunt to get the boatover on plane. is this a side effect if having way big prop and what should i do to get my prop into my operating range?? thanx guys

The prop is simply too large for your application. You won't be able to cut enought pitch out of it to make up 600 rpms. You'd be better off just buying a smaller prop than to try to rework the one you have.

Usually, the problem with the hydromotives is that they slip or blowout when planing. If you don't have that problem and instead the prop is hooking up too well so that it bogs your motor, then you must have a really deep x-dimension. Until you raise this is just going to be the cost of having too large of a prop with a deep x.

I'm just wondering if this really is the correct prop for your application. Have you calculated the slip percentage yet? I'm thinking that your application would be happiest with a round ear prop.

mxz;i agree with cord that you have to big of a prop for your boat!! i have same hull as you and i have 500hp efi motor. i turn 5100rpms with a 25 pitch labbed hydro.you can have the pitch reduced for about 300rpm gain,but still may not be enough for you! call tom at hydromotive 330-425-4266 here is another thing to do call checkmate factory and talk to mike or kipp about a new prop they have been testing with good results it is made by turning point and is called speed zone made in florida 419-562-3881 a friend of mine tryed this prop and loved it on his 270 convincor. hope this helps you bill

thanx for the replys i will call checkmate and find out about that new prop. is that a 4 blade 25 you turn? i am not sure which is my biggest problem lack of horsepower of deepX i compared with someone onhere same hull and mine was an inch deeper than theres. is it the fourth blade, the straight blade edge design(versus round ear) or just design that is giving me this stern lift with the hydro versus the bow lift with the mirage plus? :confused:

MXZ, I have the same problem with my Donzi 26ZX with the same motor, I am selling my motor and putting in a 500 EFI. I tried the 22 pitch 4-blade and it works great but I lose to much top end and would rather suffer out of the hole than lose it on top.

donzi you lose to much top end with the 22 4 blade compared to what other prop and how much mph did you lose?

I probably would say around 6mph or so, it gives me a great hole shot but I like having the top end. When I have 4 people on the boat forget about planing off in a hurry, the boat is a snail!!!

first off mxz800s dont have props. you must ride sleds. I had a 253 convincer with a 502, I tryed all kinds of props the best prop for those boats is a mach but they are out of business. I used a 141/2x24p the rpms were 4800 and this boat would handle. this may give you some idea about were to go. to be truthful this prop went back to the factory at least six times. but when we were done the prop did what I wanted, so you must know what you want with out wanting to much.

dockmech yes i have had a few sleds. i am starting to think the perfect prop is made not bought right out of the box. sheesh i thought sled clucthing was tuff:p

I just bought a pair of 28 hydromotives off this for my 29 fountain It will be interesting to see how many times I have to send these back if they are close. I am in up state N.Y. and had mike spinnelli do my props but I hear he has closed. If you told him what your boat was doing and what you wanted it to do , he would make it work if he thought he could with out going to another prop. by the way we ride polaris all over up north.

here are some results from doing a little prop testing all speeds are GPS

4 blade hydro 24 p
upwind downwind
3500 46.8 44
4000 54.3 49
4450max61.7 450061.9

3 blade 23p quicksilver chopper
up down
3500 39.5 41
4000 47 48
4950max 61.34950 61.1

3 blade mirage plus 23p
up down
3500 41.4 41.2
4000 51.5 50.8
4925max 63.1 497563.5


this was with 3/4 tank of full 80 humid day 1 foot chop 15mph winds boat was loaded for normal day out tools cooler 2 adults.

top speed for the day was 64.3 this was with ALOT of trim and only 1/2tank of fuel

the four blade gave the boat a ride that was excellent good feedback np porpoise or chinewalk but slowest to plane good bite

the three bale chopper rode ok some blowout when planing and not much feel in the steering no porpoising this was a prop i had laying around and figured what the heck

threer blade mirage plus qickest to plane but porpoised badly chinewalked and made boat ride very bow high also had to use a lot of trim for speed with this boat.

i think i am going to see if i cant get the extra rpms out ofthe fourblade if i cant i will sell it and get a 22 p 4 blade

the most i have gotten out of the setup was 67.2 that was 1/8 tank of fuel 50 degree day 2-3 foot chop

what do these numbers figure out slip wise??

thanx for all the help Rob

Rob, if your gear ratio is 1.5 and your prop is a 23p and your rpm is 4975 and your gps speed is 63.5 your prop slip comes out to .120961

Rob, your X demension must be pretty deep. The Hydromotive is designed to slip a little coming on plane. Does your 24 Hydro have a diffuser ring on it? If it does I would cut it off. But I think best plan would be to get a 22 pitch Hydro w/NO diffusser ring. If the 22 still won't turn to 4900 or 5000 rpm then have it labbed.

The 22 will also be better planning time than that 24. I'll keep my eyes out for ya for a 22 pitch Hydro.

Eric

dockmech yes my gear ratio is a 1.5 does that mean 12% slip?

Eric, no i dont have a difuser ring i am thinking i need a 22. i am sure i have a deep x CONVINCOR 300 is going to check intoitfor me.

should i buy a 22 or just have my 24 repicthed?? is there a diameter difference in these two??

mxz800 yes your slip is 12%. if you go to hill propellers they have a chart , you give them four of your known factors and they will give you the what you are looking for.

Rob, I would prefer to get the 22 pitch rather than have the 24 worked on. Just my opinion but would probably cost the same either way. And the stock 22 will be stronger. The diameters should all be the same. 15 1/4" to 15 1/2" diameter.

Maybe an IMCO shortie is in your future!:D

Eric

I, have said it before it's a ***** to change the pitch dn on a hydromotive prop ?the trailing edge is too thick and just wont work like a stock 22 . then you can alway's lab the prop add a touch of cupping and you will have almost the best of both worlds.or we can work the mirage to a 22 pitch ,and add cupping in the pitch and rake line ,thin out the blades and that would work we'll unless you always have a boat full of people? changing the pitch on a hydromotive prop is always easier with better results going up rather than down/hope I have helped Darin