General Prop Questions for 28' Checkmate

[Keytime]

Since we have a forum specifically for props and I'm a member, I'm gonna pick your brain. :mrgreen:

I have a 28' 1999 Checkmate Convincor with twin 454 EFI Mags (385hp each at the prop), Bravo 1 drives, and 27P 3-blade conventional props. This same boat was tested in the January 1999 issue of Hot Boat magazine with the same props. This was my first season with the boat and I've recorded 67mph GPS on it so far, but haven't done any dedicated high-speed runs yet. Considering the boat is 28' w/ twins, I get some definite bow-lift when coming up on plane, but I can't complain about the props performance overall. It seems to be a good all-around prop, but I'm pretty green in this department.
I plan to do some speed runs soon and my eventual goal is to GPS 80mph on this boat like the magazine article did. I figure I'll run the boat this Fall with the props as-is and then have them checked out. They have some small imperfections, but I don't know how detrimental these are to my performance.

Questions:

1. Would you recommend labbing these props for all-around performance or max speed?
2. What type and pitch of prop do you feel would give this boat maximum speed... say... in a Shootout event? :twisted:

Thanks for your help,
John

[Griff]

Exactly what props do you have?????

I would think some hydro Q 4's would work well to give more stern lift and keep the bow planted.

[pammy]

Griff,

I have a question. Can you pm me?

[Keytime]

Exactly what props do you have?????

I would think some hydro Q 4's would work well to give more stern lift and keep the bow planted.

I'll have to get a closer look at 'em over lunch today. I believe they're Mirage conventional 27P 3-blades. Am I missing any pertinent info? Pardon me, I'm currently getting up-to-speed on props. :oops:

[Griff]

Griff,

I have a question. Can you pm me?

I tried

"pammy has exceeded their stored private messages quota and can not accept further messages until they clear some space."

[Griff]

I'll have to get a closer look at 'em over lunch today. I believe they're Mirage conventional 27P 3-blades. Am I missing any pertinent info? Pardon me, I'm currently getting up-to-speed on props. :oops:


Thats the info. 27's should be 75-78 mph props if its propped correctly with 1.5 drives at 5000 or so rpms. You need to get a solid baseline with a GPS speed and exact rpm and go from there. Bravo 4 blades will get the boat on plane faster and give better cruise speeds. Even a Mirage plus will have better bite than the older Mirages

[who knows]

Sorry to hijack your thread but I am in a similair boat. And only running mirage 23's Getting 71 @ 5000rpm should IK be prop testing or leave well enough alone


MMeade

[Griff]

Sorry to hijack your thread but I am in a similair boat. And only running mirage 23's Getting 71 @ 5000rpm should IK be prop testing or leave well enough alone


MMeade


Do you have 1.36 drives????? I think you must. With 1.5's it would be 3% slip which is highly unlikely on a straight V. With 1.36's it is 11% slip which is more realistic.

[who knows]

quite possible. I'll have to look in to it. I wish I could get 3% slip.


Thanks Griff

[Keytime]

Thats the info. 27's should be 75-78 mph props if its propped correctly with 1.5 drives at 5000 or so rpms. You need to get a solid baseline with a GPS speed and exact rpm and go from there. Bravo 4 blades will get the boat on plane faster and give better cruise speeds. Even a Mirage plus will have better bite than the older Mirages

Griff, I do have the Mirage Plus props, btw. I need to confirm that my drives are 1.5's. What's the best way to determine this?

[Griff]

If you're turning 27's, then I'm 98% sure you've got 1.50's. Its possible that you have have 1.65's, but not likely. It should be stamped on the side of the sticker by the serial # on the drive.

[Keytime]

If you're turning 27's, then I'm 98% sure you've got 1.50's. Its possible that you have have 1.65's, but not likely. It should be stamped on the side of the sticker by the serial # on the drive.

Thanks again, Griff. I'll get some WFO data before winterizing. [smilie=trink39]

[Keytime]

72.2 GPS yesterday at Kaw at 4500rpm on port tach and 5200rpm on starboard tach. Starboard tach was acting a little wacky earlier. Might be new gauge time. These are the original set.

Mild "chop" from wind, not glass conditions (I'm learning how much chop is beneficial at this point. Not sure yet.)
Two people in boat with typical extras (drinks, food, cameras, anchor, etc).
80-85 degrees, 50% humidity.
I trimmed it way up till it started rockin' on me. Probably a little too speed-greedy.
That's with 27P 3-blade Mirage Plus's.

I'm gonna get it out in the morning at LOTO on Fall Harbor Hop weekend and see how it does solo. From then, probably winterize, have the props cleaned up, and do some homework for the spring.

[bbladesprops]

Checkmates love bow lift. Mirage Plus props will give good top end but suffer low end and cruise. I do not recomend Hydro Q4's. They have too much stern lift and will be a bummer at WOT. Best all around is Bravo 1 props Labbed specific to your boat.

Brett

[Keytime]

Checkmates love bow lift. Mirage Plus props will give good top end but suffer low end and cruise. I do not recomend Hydro Q4's. They have too much stern lift and will be a bummer at WOT. Best all around is Bravo 1 props Labbed specific to your boat.

Brett

Don't I need more stern lift with that twin-engine set-up in a 28' boat?

My manual reads 4600-5000rpm at WOT. If I'm spinning it to 5200WOT with 27P 3-blades, should I try a higher pitch prop for more top-end?

Another question: I had 5 adults in the boat last weekend and to cruise at about 30mph to sightsee, I had to put the trim tabs down a bit with my 27P. I assume that the Bravo 1 props you're recommending would help with that.

[Keytime]

Checkmates love bow lift. Mirage Plus props will give good top end but suffer low end and cruise. I do not recomend Hydro Q4's. They have too much stern lift and will be a bummer at WOT. Best all around is Bravo 1 props Labbed specific to your boat.

Brett

Brett,

As far as Bravo 1's are concerned, would you recommend a 26P 4-blade Bravo 1?

I"m wondering how these (labbed) would compared overall to my current 27P Mirage Plus 3-blades where the following are concerned:

1. Getting on plane
2. Cruising
3. Top-speed

Thanks!
John

[Griff]

Planing would be much better and cruise speeds will go up. Top end????? You won't know till you try. You may loose a couple mph that can be regained, plus more, by labbing. You need to verify your tach accuracy to determine what pitch, for sure. You should be hitting the rev limiter by 5200rpms. The 26 B1's will turn about the same rpms as your current 27 Mirage plus props.

[JasonSmith]

Bdorkity has a set of bravo 1 26's I'm trying to get him to sell so he can get the right propellers on his boat. PM him & make him an offer to buy his. You'll probably have to go take them off for him. He is mechanically retarded.

[Griff]

Bdorkity has a set of bravo 1 26's I'm trying to get him to sell so he can get the right propellers on his boat. PM him & make him an offer to buy his. You'll probably have to go take them off for him. He is mechanically retarded.


I haven't met anyone really that didn't think I was a dick at first.:mrgreen:

I hope you don't wonder why they think that[smilie=nutkick.gif] :mrgreen: :mrgreen: :mrgreen:

[JasonSmith]

I hope you don't wonder why they think that[smilie=nutkick.gif] :mrgreen: :mrgreen: :mrgreen:
Nope, clear as day. But you gotta know me to really hate me. Ask my ex-wife.:mrgreen:

[Keytime]

Jason, with guys like you, Lakerat, and T-38 on this forum (not to mention the political debates lately), I had to laugh when concern was expressed about me and dwtinc trading jabs. :mrgreen: