300R Prop Help

[Boats&Taxes]

I'm suspicious of the props only being 1" different... I'm sure somebody else will chime in.

Anyway, that's a Concept to be proud of! Every mile per hour from here is gonna cost you

Not sure what to tell you... Both brand new props in box.

Thanks, a great all around boat. I have had two big fountains and miss the speed. This boat wanted single outboard center console that was family friendly but at the same time I knew I would not be happy in 50mph center console. I think with the right prop the boat has 70 in it and that was my goal. Off course once I get there i will want more speed. Did someone say blueprint

[Pulsare2400]

There is not enough difference in rpm between the two props. If the 23P was spot on and the engine was not reducing the % throttle at WOT, then the 24P should have turned closer to 6230 rpm. However, there is another possibility. You did run 67.9 mph at 6400 rpm and that equals 16% slip if I use 23.3 for the pitch which is a realistic number for the a 24P Bravo FS. At 6400 it is likely that the engine is not pulling power so let's assume that is a good number and 100% throttle. If that number was good then you ran 66.1 mph at 6500 rpm which is also 16% slip using 22.3 for the pitch of a 23 Bravo FS. Both props ran the same slip even though the 24P is a straight casting and the 23P is a 22P casting with additional cup added to it. So I would assume the props are similar. My guess would be the engine pulled power and reduced the WOT less than 100% and if the engine did not do that, you would have turned the 23P FS prop to 6600 - 6700 rpm and run between 67 - 67.8 mph (if the engine made the same power at that rpm which it does not). So the pitch change really dropped the rpm around 250 rpm which would make sense. So If you switch to a 25P FS, and my hunch above is correct, it will turn 6150 rpm with the 25P, and you will run almost the same mph, perhaps 0.5 - 1 mph faster if you are lucky providing the slip stays the same. I have a 300R on a 2400 Checkmate Pulsare, and I turn a 24P Bravo FS to 6200 rpm at 72 mph and that is slightly less than 9% slip, but my 300R is a dog and won't run on the top end. I have trimmed it higher and run 6450 rpm but at the same speed because the slip increased. Mercury Racing told me that 6250 rpm is where I want to be but I doubt there is much difference in HP between 6100 - 6400.

[Boats&Taxes]

There is not enough difference in rpm between the two props. If the 23P was spot on and the engine was not reducing the % throttle at WOT, then the 24P should have turned closer to 6230 rpm. However, there is another possibility. You did run 67.9 mph at 6400 rpm and that equals 16% slip if I use 23.3 for the pitch which is a realistic number for the a 24P Bravo FS. At 6400 it is likely that the engine is not pulling power so let's assume that is a good number and 100% throttle. If that number was good then you ran 66.1 mph at 6500 rpm which is also 16% slip using 22.3 for the pitch of a 23 Bravo FS. Both props ran the same slip even though the 24P is a straight casting and the 23P is a 22P casting with additional cup added to it. So I would assume the props are similar. My guess would be the engine pulled power and reduced the WOT less than 100% and if the engine did not do that, you would have turned the 23P FS prop to 6600 - 6700 rpm and run between 67 - 67.8 mph (if the engine made the same power at that rpm which it does not). So the pitch change really dropped the rpm around 250 rpm which would make sense. So If you switch to a 25P FS, and my hunch above is correct, it will turn 6150 rpm with the 25P, and you will run almost the same mph, perhaps 0.5 - 1 mph faster if you are lucky providing the slip stays the same. I have a 300R on a 2400 Checkmate Pulsare, and I turn a 24P Bravo FS to 6200 rpm at 72 mph and that is slightly less than 9% slip, but my 300R is a dog and won't run on the top end. I have trimmed it higher and run 6450 rpm but at the same speed because the slip increased. Mercury Racing told me that 6250 rpm is where I want to be but I doubt there is much difference in HP between 6100 - 6400.

How do I get my slip% down? By trimming it lower? I have tried all combinations of trim and jack plate. The 67.9 @6,400 was the best trim. Lower trim caused speed and RPM to drop and higher trim caused the speed to drop and RPM go higher. I still think I need to plug a couple intake holes since I am jacked as high as I can go and still have water pressure.

[TraceF3]

Getting below 9% is magical...... everything has to be perfect

[Boats&Taxes]

Getting below 9% is magical...... everything has to be perfect

right now I would just be happy getting to around 12-14% with the 24P to get me past my goal.

[TraceF3]

Good luck to you my friend. Are we gonna see all these props for sale in the props forum?

[Boats&Taxes]

Good luck to you my friend. Are we gonna see all these props for sale in the props forum?

Thanks, luckily the boat was a new build and since the have never rigged a 300R on that hull they were more than nice and let me try 4 props on their dime. I only have the 23 and 24 still in my possession and looks like I will be sending the 23 back.

Next prop I try will have to buy or borrow from someone. I guess I should start looking to see if anyone is selling a FS 25P. I wish there was a company locally that would let you rent a props for the afternoon so I could try them all and then buy one. I called Bblades and they do not do the FS props in their prop program.

[TraceF3]

I have a 2020 Checkmate 2400 closed deck with a 300R and a 24P Bravo FS. It runs 72 mph GPS at 6200 rpm. I have trimmed it much higher and run the same speed at 6450 rpm. It has a hydraulic jack plate. I am not impressed with the motor, but if I was in the boat alone, I think it would easily run 73 mph, and perhaps 74 mph under perfect conditions.

Here is a Mercury webpage about adaptive speed control that will explain what you might be experiencing

Optimizing Your Ride: Adaptive Speed Control Explained | Mercury Racing

[TraceF3]

Thanks, luckily the boat was a new build and since the have never rigged a 300R on that hull they were more than nice and let me try 4 props on their dime. I only have the 23 and 24 still in my possession and looks like I will be sending the 23 back.

Next prop I try will have to buy or borrow from someone. I guess I should start looking to see if anyone is selling a FS 25P. I wish there was a company locally that would let you rent a props for the afternoon so I could try them all and then buy one. I called Bblades and they do not do the FS props in their prop program.

Did you end up with any props you don't want? I'm looking for a 24p FS, maybe a 25p

[Pulsare2400]

Here is a Mercury webpage about adaptive speed control that will explain what you might be experiencing

Optimizing Your Ride: Adaptive Speed Control Explained | Mercury Racing

Thanks, I am aware of the ACS, but I don't think it was active when I ran 72 mph at 6200 rpm. It must have been active when I ran almost 6450 rpm because that is also the rev limiter, but it was over trimmed, and the jack plate a bit too high then, because it ran 1 mph slower at 250 rpm higher. My friend has a 300R on his 2400 Checkmate, and my boat will run about 67 with zero trim and I gain the rest of the speed with the trim. His boat will run 72 mph with barely much trim and then goes into violent chine walk. His might be limited by the ACS since his rpm at 72 mph is closer to 6400 rpm.

[TraceF3]

FWIW the comments section at the bottom of the page says the ACS can't be deactivated.

Which hull does your friend have? And what prop was he running?

I have one of the CM unicorns. The bow rider with the full dash, full windshield and crawl thru. I've read there were only 3 or 4 made. It's a wind tunnel but I solved that with a tightly made bow cover.

Motor is going on today and I'm wondering where to start with props. 24p FS?

[Pulsare2400]

FWIW the comments section at the bottom of the page says the ACS can't be deactivated.

Which hull does your friend have? And what prop was he running?

I have one of the CM unicorns. The bow rider with the full dash, full windshield and crawl thru. I've read there were only 3 or 4 made. It's a wind tunnel but I solved that with a tightly made bow cover.

Motor is going on today and I'm wondering where to start with props. 24p FS?

Mine is a 2400 closed deck with a 300R and a Bravo 24P FS and it was the 2nd last boat built in Bucyrus. My friends is a 2400 BRX, with a 300R, Bravo 24P FS and the same jack plate.

[TraceF3]

What year? Mine is a 2007. Where was it made? "Checkmate History" on their website doesn't say much.

[Pulsare2400]

What year? Mine is a 2007. Where was it made? "Checkmate History" on their website doesn't say much.

Mine is a 2020 and it was completed and I picked it up around Oct 31 / 2019. My friend's is a 2020 and he picked it up around April 2020. The bottom hull mold is of course identical between a long deck and a BRX, but Checkmate had more than Pulsare 2400 hull mold. His and mine came from different but supposedly identical hull molds, at least that is the best of what we can determine. I don't think that is the reason for the performance difference, as I have other "engine symptoms" he does not have, like a very rich exhaust smell when warmed up and idling.

[Boats&Taxes]

Did you end up with any props you don't want? I'm looking for a 24p FS, maybe a 25p

As of now all the props they let me borrow went back to them. I now have a 24P that I will either end up selling to get a 25 or going to have it worked to see if this prop will be the one. Weather has been too cold to do any testing the last 3 weeks.