over the hub choppers

[illMATTic]

do these props generaly take more hp to turn? do they run better jacked up? i am asking cuz i tried out a merc 28P chopper and lost alot of speed and rpm. i am running a 26P lazerII now about 1.5" below the pad. this lazerII is the best i have found so far.

any suggestions?

stock 2.4 200
6" setback
16' checkmate
best of 74 mph @ 6400 rpm

i would like to do a bit faster this season

[pyro]

you should have been turning the chopper to at least 6200, maybe it was still too deep, needs more jack. Choppers won't develop their full rpm unless they're at the right height, which is different on each boat. You can tell when they're too high, cause rpm starts to go up with height while speed stays the same.

Got LWPU?

-chad

[wideglide55]

Choppers are made to be run high,older Merc choppers have alot of slip on heavier boats.I ran a 28 Merc chopper on my rig,boat went 85 on the limiter at 6400,went to a 29 Mazco RE-3 boat went 96 mph at 6400. Thats 11mph difference. Are you running a low water pick-up? If so try that 28 after you raise it up some. For best all around performance you need a jackplate you can adjust while running. That way you can leave the big prop on,jack it down for take-off and up when you want to fly it.

[illMATTic]

it was a A3 chopper i think. i dont have a lwp yet. that is mainly why i didnt raise the motor.

do i want a large or small ear? this A3 i had looked super big.

[pyro]

It's going to be A4 or A5. http://abiossa.gearhost.net/adamsdock/chopper.html

[WATERWINGS]

That is good stuff to know, very informative, thanks Chad.

[illMATTic]

it was the big ear later A5. i didnt know it came with the locking tab. i guess thats why i had trouble installing it.

so given my set up i should be able to turn a 28P chopper right? i just have to raise it up a bit more?

[LakeRaider]

I have a 1978 Predictor and just built an XR2 that dynoed right at 200 hp.
iiMATTic, What jackplate you using? LakeRaider

[illMATTic]

I am running the bobs convertable. it has a -5 degree trim to keep the hopping down at low speeds. i like it. two bad its only a two pc. a bit hard to adjust.

[SportJ-US-1]

Choppers want to be way up. Like the prop shaft at the bottom of the boat or if a tunnel at the surface of the water at least. I've run them as high as 1 5/8" above the surface of the water on some tunnels. Choppers require low water pickups to work right.

[graemers]

Thanks for the link pyro. Good info.

[david martin]

Hey Pyro


The chart was great!I now Know that I am running a 30p bigear chopper.
Is there any charts on lowerunits?:)