I have a 1998 Cobra bass boat with a 200 Johnson Venom. I installed an 8" jackplate on it and it just does not seem to be set right. If you run down the lake at about half throttle and the trim about in the center it cavitate and then catch water again. When I am at full throttle and it is trimed out with the bow lifted it act as if it sort of skipps across the water or you might even say hops.
Give details...prop shaft to pad height, rpms, prop size.
Butch Brotherton
Monticello, Iowa
2011 Nitro Z8 250 Mercury Pro XS
Not exactly sure of prop shaft height. It is somewhere between 3 and 4 in below the pad. I has 24 raker 3 blade prop and at wide open throttle it is about 5600 to 5800 rpm
You need to measure the heigth of the engine shaft in relation to the hull. Get a three foot level and place it on the pad and level the pad out by jacking the tongue up or down. Now take a level and place it on the cavitation plate of the motor and level that out. Measure from the ground up to the lowest point on the pad and then from the ground to the center of the prop shaft. Subtract the two and that is your pad to prop shaft relationship. You may find it is higher then you think. It also sounds like you need the prop worked as it is not locking up very well. Have you got a GPS to give a speed. With the prop you have a theoretical speed from a prop calculator is 64 at 5600 and 66 at 5800. Let us know what you are doing.
You didn't say just exactly what model of Viper Cobra you have. And yes, I go along with Gary L. Sounds like the engine is a tad too high on the jackplate. Set it at 3.5" below the pad and go from there. Also, props flex and over time get a little out of whack! If you haven't had anything done to it in 8 years I'm sure it needs (at least) re-cupped and probably re-pitched. Also consider getting some 2" spacers so you'll have 10" of setback.
I thought I would be on Easy Street by now but somehow I missed the off ramp!
Well I must respond to lakeracerIt wust be the same reason you bought an E-TEC
It is fun to go fast but But for the most part the name of the game is to put the trolling motor in the water and fish.
Just a question, You didn't have to take it so personal!
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