Okay the boat is Kunkles purple boat 620 hp and 650 on torque spinning a 26 bravo. I belive the speed really was 83. something but it was close to 84. "GPS" But he also said the engine was not broke in yet so he did not really hammer on it. So their for with a bit more time on break in and some tweaking it could do better. This is a fact and not here say and I feel they know Checkmates pretty good because they have had them since the sixties.

Maybe it all comes down to the driver or do we really have the HP we think we have or are we trimming the crap out of it when its not needed.

I am no pro by no means on boat driving but if it came out of Kunkles moulth you can take that to the bank.

PS
the engine has no kind of forced air, nos, or any type of huffer in no way shape or form. pump gas all day long

Okay the boat is Kunkles purple boat 620 hp and 650 on torque spinning a 26 bravo. I belive the speed really was 83. something but it was close to 84. "GPS" But he also said the engine was not broke in yet so he did not really hammer on it. So their for with a bit more time on break in and some tweaking it could do better. This is a fact and not here say and I feel they know Checkmates pretty good because they have had them since the sixties.

Maybe it all comes down to the driver or do we really have the HP we think we have or are we trimming the crap out of it when its not needed.

I am no pro by no means on boat driving but if it came out of Kunkles moulth you can take that to the bank.

PS
the engine has no kind of forced air, nos, or any type of huffer in no way shape or form. pump gas all day long

Sinking Ship, is sounds like we could all learn somethng from your friend and his Checkmate. 5400 RPM, 1.5 drive ratio W/ 26" pitch prop at 83 MPH gives 6.3% propeller slip. I have a 283 W/ twin 502 MPI's running 80 MPH (GPS) at 4800 RPM W/ 29" labbed Mirage Plus props (9% propeller slip). Does he have any updates to help improve prop efficiency (i.e. ext box, shorty drive, nose cone...)? 6.3% prop slip is an amazing number.
Thanks.

Are you running 3-blades? I'm spinning 5100-5200rpm WOT w/ 27P Mirage Plus 3-blades and twin 454 EFI Mags. Thinking I might need to try 29's like yours.

I would give them a call their 2004 300 Convicor has been radared at 107. They have been dealing with Checkmates since early sixites I have seen the purple flammed boat and their is no nose cone on the drive. I feel the bravo 4 blades props are the best on a Convincor.

http://www.kunkelsmarine.com/newboats.html

Keytime, yes the Mirage Plus props are 3 blades. I believe your boat was the actual boat used in a Hot Boat article and they reported 81 MPH with 31" props (I don't have the article, this is just from memory). I thought the rev limit was set @ 5150 RPM on the MPI engines so more prop may help.
Purple, looking at the pictures on the link you posted, the 2004 boat has an IMCO lower which could be a -2?? Also, the hull has a notch all the way across the transom. I have never noticed this on a Checkmate before, are newer boats built this way (or was that boat modified or a special build)? As far as the 4 blade prop theory, I have a set of Bravo One labbed 30" props I will be testing next year when the boat's updates are complete (Stellings boxes, IMCO steering, engine upgrades to @ 500HP, Mechanical Indicators) and I hope they work with the new set up...

The notch is factory on the 2004 blue flammed 300 Convincor that was radared at 107 mph and yes that boat was running a imco.

But also the 2006 300 purple flammed Convincor that runs 84 has the same factory notch running a factory bravo drive with a factory bravo 1 26p prop. I have seen in person both boats and both boats are still at Kunkles.

Both boats have never been altered in any way shape or form on the hull. Both boats have the orginal gel-coat that came from the factory.

The 30 footer is the 300 now.

What is this "notch"? Is it a step?

Is this the 107mph boat?
http://www.kunkelsmarine.com/newboats2.html

Ok. Essentially a notched transom. My apologies. I don't wake up till about noon on Wednesday.