Surface running props

[skialot2]

I need a bigger prop for my Checkmate. 1989 17' Spectra 2.5 200 HP. Propshaft level with the pad. I want a prop with lots of bow lift and no stern lift. I will need a mid 30's pitch. I have always run choppers. I want a 4 blade for the stability. Any other recommendations?

[Carter Powell]

Mercury Trophy, Mazco RE 4, Carter Powell

[David - WI]

That must be one fast Checkmate... "mid–30" pitch?

[OnPad]

A few more that might work? Signature eagle 4, Chopper 4 or drag 4. Performance propeller sells a few different 4 blade models. Mazco hp4, Merc E.T., Promax, or Bravo.

Out of the propellers I've run, a trophy and drag style were the most controllable. Which might be a consideration on a 17' boat.

28p is about all my 2.5 litres want to pull with 14 1/2" diameter, and 4 blades. That's with the propshaft above the bottom. I have run a 13 1/2"×30p drag 4, and 32p 3 blade cleaver successfully, but wasn't anywhere close to being able to pull a 35p 4 blade cleaver.

[skialot2]

I am very surprised how big of a pitch I seem to need. Right now I am running a 26P quicksilver chopper that was Labbed/Reworked/Cupped before I bought it. When I had it on my Glastron it ran the same RPM as my brand-new 30P Hill signature performer 3 Chopper that I lost when my 150 mid broke off.


I haven't gotten anywhere near top speed. Motor is not broken in yet. But cruising at 3000RPM is 40MPH. Attachment 532817

When I jump on it, the boat accelerates really hard. After about 2-3 seconds I have to back off. The motor spins up to 7000RPM and is still pulling hard. My boats GPS speedo only goes to 60. But my phone had a max speed of 69 MPH. With the right prop and a bunch more seat time, I think the boat should hit around 80MPH.


Boat is a 1989 17' Checkmate Spectra 171. Approx. 1100 lbs. Rated for a 150
Motor is a plain 2000 2.5 200HP Carb. No markings on block. Freshly rebuilt with all OEM parts. Oil injection deleted. No porting but Boyeson reeds. Bobs exhaust tuner and exhaust outlet. CDM ignition has been converted back to CD. Limiter has been removed.

[David - WI]

You would need to be going 100+ mph to turn a 35" prop at more than the stock 5800 rpm?

[rock]

Does seem a lot of pitch. I couldn't turn a labbed 30 ET on my Allison with a 200xs ROS.

Rock

[skialot2]

You would need to be going 100+ mph to turn a 35" prop at more than the stock 5800 rpm?

If I use a prop slip calculator and put in my numbers at cruising speed. 30 pitch prop. 1.87 ratio. 3000 RPM. 40 MPH. I get a calculated prop slip of 12%. If I just change the pitch to 35. and rpms to 5600 (stock redline) With the same calculated slip of 12% I get a calculated speed of 87 MPH. But I think a 35 will be too big. maybe a 33 or 34 at most. With a 33 calculated speed would be 82 @ 5600.

[skialot2]

Does seem a lot of pitch. I couldn't turn a labbed 30 ET on my Allison with a 200xs ROS.

Rock

But doesn't a 200xs ROS turn over 7000RPM and would require a much smaller prop than a regular 200 that only spins to 5600?

[rjdubiel]

do you have metal lower connecting rod bearings? What electrics are you running? if you are trying to get your motor to run at 5600 RPM for your top speed you will not be happy. That thing will be a dog out of the hole. Answers to the first two questions will let us know what you should be running for RPM, not the stock max RPM merc states.

[David]

200XS runs 6800, some say 7000, certainly no more. 1.75 gears.

Is your oil injection removed, along with the rev limiter?

If I were spending your money, I suppose 30 might be the next step.

[David - WI]

Prop slip at "cruising speed" is way more than at max speed... and you have the limiter removed, so 6,400rpm is probably peak power?

[rock]

But doesn't a 200xs ROS turn over 7000RPM and would require a much smaller prop than a regular 200 that only spins to 5600?

The 200xs is a direct injected motor which means it has way more torque than your 200. You need torque to turn a large wheel. RPMs mean nothing if you can't get there.

Rock

[skialot2]

do you have metal lower connecting rod bearings? What electrics are you running? if you are trying to get your motor to run at 5600 RPM for your top speed you will not be happy. That thing will be a dog out of the hole. Answers to the first two questions will let us know what you should be running for RPM, not the stock max RPM merc states.

Yes I have metal cage rod bearings. All rod and main bearing are brand new. All the electronics came off a stock 98 150. Nothing special.

[skialot2]

Thanks everybody for the input. This really wasn't supposed to be about what pitch to run. Pitch kind of picks itself depending on the RPM's you want to run. The prop I am using now is a Quicksilver Chopper that was reworked by someone before I bought it from eBay. When I was using it on my Glastron with my 135 it ran 5500RPM's. (No LWP. 2 top holes plugged. Ran 3" below keel. No pad) It ran fine. But I noticed one blade had a couple minor bends on the face. I called Hill Marine to have it reconditioned. When I told Ron the prop was already probably labbed, he said you never know what someone else did to it. Then suggested I buy one of their Signature Choppers. So, I did. I ordered a 28P Chopper 3. It ran 400 RPM higher on 5 MPH slower. So I sent it back and exchanged it for a 30 Pitch. That 30P prop ran the same 5500 RPM, but still 2 MPH slower as the labbed 26 chopper. When I switched to my Checkmate with the 150, it ran 5600 with the Hill Chopper until I lost it when the mid section broke. When I fixed the 150. It ran 5600 with the Quicksilver Chopper. That is why I say this prop has been reworked to a 30P. Now that I switched to a fresh 200 with some bolt on mods done, I am going to need a few more inches of pitch. Any suggestions on what RPM range I should run. I want it to go over the stock range. But I definitely don't want to be spinning this motor to 7k.