Convincor 25' What to prop it?
 

I have a 90' Checkmate Convincor 25ft, Currently has 454 with bravo, It has a 4 blade 26P bravo prop on it now. It currently does 55 On GPS and is only running around 3400 rpm. I really am new to these style boat and especially to understanding the prop set up and changing and what it will do. I will say with the current prop it pulls out the hole good and is obviously decent on fuel now only pulling 3400. I would like to get some more top end out of it that I know it has, so Where do I go from here?? Higher, lower P? Dont really understand it. thanks!

sounds like something is way off!!!!!!

what 454 is in the boat? 300 hp, 330 hp?

and your sure about it spinning to 3,400 rpm not 4400?


if you are 100% reved out by 3400 rpm and your going 55 you have a rocketship on your hands esp if it h=gets on plane good.

sounds like something else is off, tach not right, something.
either way, im going to geuss from my boat and my testing that 300-330 hp would want a 22p 4 blade or maybe even a little less like a 21p 3 blade
i think 200 rpm or so per pitch change so even a 22 p will only be about 3600-3700

I'm guessing the tach is way off. I know a couple people with a 25 checkmate, one with the 330hp that runs a 23p mirage and the other with the 365hp mag that's running a 24p bravo 1. There's no way they are running 3400 rpm, I can tell you that. The guy I know with the 454 MAG runs a consistent 58-60, but has had it to about 64 at it's best. I'd say you're probably right in the ballpark of where it should be.

Well judging from what your saying, I guess the tack must be off. It appears to be an older tach, I dont know if the original tach. I will say just judging the sound of the motor it sounds like its opened right up and screaming along. Im just trying to think of way to check the tach before I consider replacing it. The motor has been gone through a few years ago, I just bought the boat this year, so who knows. Ok guys, I just went out and checked I was mistaken it currently has a 26P bravo 4blade prop on it!

I'm running the same boat and same prop you have right now....but a different engine. When my engine was stock, I was expiermenting with props in the 23 pitch range. ..23P Mirage, 23 pitch Bravo1, 22pitch Bravo 1 , 23 Pitch Hydromotive. That's where I would start if I were you. Ebay is a great place to expierement with props. Your current prop is a very nice prop, just not for your boat....right now. If it's in great shape it should bring 250-300 dollars off ebay and you can start expiermenting with others!

Oh yea, I haven't done the prop calculator on your speed verses rpm verses pitch, but I think I'm running about low-mid 50's around 3400-3500 rpm also, so I don't think your tach is off.

Hope im not sounding too stupid here, but am I wanting to look at 3 or 4 blade props? I believe I want 4 blad props correct? Is mirage style not a 3 blade? thanks alot for you help!

All the Mirages I've seen are 3 blade. Most Hydromotives are 4 blade, but there are also 3 blade Hydros. You can look for a Mirage or a Hydromotive or a Bravo1 are the 3 I would suggest trying. The 4 blade Hydyo's and Bravo's will spin close to the same of each other on your boat, the 3 blade Mirage in the same pitch will spin a couple hundred rpm higher than the 4 blade Hydro's/Mirages.

If you're asking weather you should be looking for a 3 or 4 blade prop...it's up to you. That's where the expierementation comes in. Finding the prop that works the best for your set up. Any of the 3 props I mentioned in a 22-23 pitch range would be a good choice to start out. Search around for one and find a good deal.

A 26 B1 turning 3400 @ 55 mph would be -1.28% slip. Impossible.

Let us know if you would like to test some stock propellers.

B

So are you saying my tach is once again off or???????

I would think so. Depending on what motor, Mag or non Mag, you should be in the mid to upper 4000's!!!

Low to mid 50's at 3400-3500 RPM with a supercharged 454?????

Why give any advice to the guy at all if you have no idea what you're talking about?

Supercharged 454 at 3400, right.....:bsflag:

I dont know where your getting supercharged 454 from but it is just a stocker 454 non mag, its a 1990 that has been refreshed 3 years ago thats it.

i would replace your tach and start with a 22p bravo1. not sure on your location, but i have a 22p stock you could try and a 23p mirage plus you could try.

No, not you, bigsbetter. Sorry for any confusion. I still think your tach is off though. You WOT rpm should be 4200-4600 with that motor, I have the same motor just different year. My boat is 23', stock 454/330hp (non mag) and I've been running a 23p Mirage (not plus) and spinning about 4700 rpm in the warmer weather, and about 4800, maybe a touch more, in cooler weather. When I talked to Brett (bblades) he suggested either a 24p Bravo 1 4 blade labbed or a 22p Bravo 1 4 blade stock or re-work the 23p Mirage 3 blade for what suited the boat. Anyways, I would think you should be right around the same prop, and as Brett said, what your numbers are right now, it's impossible.

go with a stock 22p, trust me. save your money. find a nice used 22p and go for it.
i love the 4 blade on my boat. my boat is a 26, but prob a tad lighter then the older boat, 375 hp and i could hit the rev limiter on the right days with my 22p. i went to a labbed 24 and didnt get much out of it, but it doesnt hit the limiter anymore. stock 24 i was way low on the tach.
go with the 22, i bet its right on and handles better and a better cruz speed

I'd love to go with the 4 blade Bravo 1, I tried a 23p Hydro 4 blade and I was a tad too low in rpm, 4400. I loved the way it took off and cruise speed, but I needed more bow lift out of it. My Mirage has great bow lift, just blows out alot and not real good cruise speed. If I could get my hands on a 22 or 24 Bravo and try it first I would, but I'm not ready to buy anything right now anyways. Work had been slow, and I figure my prop gets the job done for now anyways. The 4 blade does feel alot better though!!!

Unless he's got a 1.3 ratio outdrive. That would make it alot more feezeable.

Wooo! I was referring to his boat and prop set up being the same as mine. At around 3500 rpm I'm cruiseing along around low-mid 50's. I wasn't saying that 3400-3500rpm is my WOT top end speed, That's just a fast cruise for me, if that is where the confusion was. It may be 3500 rpm and 50-51 mph, I'm not sure excactly, but it's close. My engine turns 4800-4900 at WOT and runs 70-71mph.

Fair enough, my apologies to you. In your post though it sounded like you were telling him that 34-3500 RPM was your WOT at low to mid 50's and that's where he should be also. If that was the case, then no, it's not where he should be. My mistake, but next time please be clear with what you're saying.

Sorry, I guess it did sound like that. Since I have the same boat and the same prop and probably the same outdrive, I was trying to determine if his tach is off by comparing my boat speed at that rpm. It (his tach)may be off but I don't think it's off by very far. That was my intent. Sorry for the confusion.


Another point. These Convincors have a tendency to porpoise at cruise speeds and a 4 blade Hydro can help with SOME of it. It help a very little on my boat when I was expiermenting.

Thanks alot guys for you replies and help! How can I find out for sure what gear ratio I am dealing with in this bravo? I have the numbers off it, but where can I go to figure out what ratio it is, or do I just know by the year/generation bravo it is?

Sometimes the ratio is stamped on the side of the drive. Most likely the ratio has not been changed, but it's possible. To be positve of the gear ratio, you can put the drive into gear and mark the prop and mark the engine and turn your engine over by hand. If you have a 1.5:1 ratio, the engine will turn 1.5 times around and the prop will turn 1 time.

well I have the same boat as well, to me sounds like the tach is way off, the #'s don't add up..the 3400 or the 55mph, one is off, I run a 22 bravo 1 with my 509, right now turns about 5200 and 67 mph, and thats with a small 750 carb and stock small roller cam...still playing...Rob

Ok, now I'm confused, you say here you are running a 24p bravo 1 @3400 but on the checkmate site you are asking the same questions but say you are running a 26p ok which are you running ????

i have a 22p if your ever in the bostom area you are welcome to try it

I corrected that in my second post on here to 26P, and just edited the first post for ya! lol sorry Thanks for the offer noyzee but probably wont be making it around boston anytime soon, Im fishing around on ebay and some other places everyday. I am going to double check my tach reading this weekend if I can get out when and if it ever stops raining around here!

Funny, my good friend lives just outside of Boston! I only make it out there a couple times a year, but he is back here (Syracuse, NY) every few weekends. I've searched high and low for a used 22p Bravo, and not really any luck. It seems you can find used 24p all over, and I figured I'd just end up going with a 24p and having it labbed. By the time I would get done with the price of a used 24p and labbing it, it would be the price of a new 22p. What would you want for it? Is it a solid hub?

I see that you're from Utica, you're only about 30 mins from me! Where do you boat, Oneida Lake?

I see that you're from Utica, you're only about 30 mins from me! Where do you boat, Oneida Lake? I'm on the north shore of the lake, right near Stern Drive Specialist.

cool, yea, im outside of boston as well. im in peabody ma.
im not selling my prop, i want it for a spare. i would be willing to ship it out to you to try it out so you know if you wanted to cover shipping. its a new prop last year.

i went with a 24 and had it labbed etc, not worth it. i got nothing out of it but maybe 1 mph at the very most.
it gets on plane slower, has the same cruz speed at 3k, 3200k and 3400k.

I couldn't do that, but I really appreciate the offer! I will definitely keep that in mind when I'm ready to buy though. I've always heard good things about having a prop labbed, but at the same time I would be pissed if I dinged it up. Again, thanks for the offer, but I wouldn't want something to happen to it and have to replace it for you.

Yeah we have been going up on oneida, going up to the thousand islands for the 4th. I usually launch at Holmes marina on the sylvan beach end. We plan on being out saturday for frogfest at verona beach if it doesnt turn out to be a washout like they are forecasting. Im going to have to verify what my tach is reading once more, I would like to try a 22 on it though and see what happens. Also hoping my guy calls me tommorow and says my windshield is ready! Took all the glass out and having it blacked out. Or I will be running a what appears to be sanford and sons boat lol.

We'll be down at Sylvan Beach on Saturday (weather permitting). A bunch of us go every year for my b-day and usually party at the Crazy Clam. I was hoping to bring the boat and tie up in the canal so no one would have to drive afterwards. I guess now we'll be playing it by ear...

We usually hang out at 3 Mile Bay, not sure if you ever make it down there or not. June 27th should be a great time down there, it use to be the Pig Roast every year but they aren't doing it this year. People are still going, it's tradition!!! I'll have to keep my eye out for the S&S windshield or a blacked out one. Anyways, if you want to try my prop you're more than welcome. I run a 23p Mirage 3 blade, or like you said a 22p Bravo 4 blade would probably work best. Let me know, I can meet you at the launch or something.

my offer stands for you as well. gotta help out a fellow checkmater, and id hate to see you guys go threw the pains of the prop game like i have been doing.
however, you brake it, you buy it. lol

We'll be over on canal a little earlier then going over to verona beach. I know where 3 mile bay is, just got the boat this year and have not been down there yet, I finally have a big enough boat to hang out in the bay lol! Thanks for that offer of trying the prop out too, Im going to double check my R's when were out. And yea hoping for the blackout tomorow not the S&S. My boat is completely red with no graphics on it yet and it will have a black or no windshield lol.

For what it's worth, I also tried a labbed 24 Bravo on my boat and it didn't pick up any speed at WOT however it was down about 300-400 RPM compared to the 22 Bravo. It took longer to plane off and just seemed to be in a bind all of the time, so I went back with a stock 22 Bravo and I'm much happier.:drink:

Pretty sure yall are making me lean to that stock 22 bravo....

Just curious if yall know or could tell me how much water my boat is drafting? We are planning a trip to unfamiliar waters this weekend and want to make sure im safe there.