Re: jack plate
I agree with most of what others have said. Make sure you've got a good cupped prop first. Yes a jack plate can be used to lower an outboard most simply due to the angle of transom. How much is a function of the angle of the transom and the height of the rear of the plate where the outboard is mounted relative to the front of the plate that is mounted to the transom. The most extreme can be accomplished by mounting the jack plate backwards. But here's the rub so to speak, jack plates are designed to raise a motor not lower it, so the rear plate is generally already higher than the front plate at the lowest setting. The other problem that arises is that unless the motor is raised up higher than it was originally on the transom, the motor can no longer be fully tilted up due to the set back resulting in the steering arm, the hood latch, and even the hood itself ramming into the top of the transom instead of going into the motor well as they originally did. Been there done that and "wrong headed" would be the correct term for the attempt.
What everyone is ignoring is the function and benefits of a jack plate in the first place. Jack plates do 3 things. They move the prop back into "cleaner" water away from the turbulence caused by the hull, they move the prop back into the water wave that follows the boat essentially running it deeper than when attached at the same height on the transom, and they provide more leverage for the motor to raise the bow with less trim due to the setback. So, it is not really about lowering the motor, but about getting the same effect by moving it back from the hull.
All of this is from my own experience in various efforts to correct the extreme ventilation problems with my own boat. While cutting down a section of my beautiful newly renovated transom 1 1/2" to further lower the motor did greatly improve on the problem, it did not fully solve it as I still had to back off the throttle and trim way down to make turns and trim way down on take off. Also, lost 3mph off the top end. After adding a 6" jack plate with the same motor and prop and with the motor now at the original transom height I am now able to make full throttle, tight turns and to take off with full up trim without ventilating. What this means is that I can raise the motor even higher. Probably will need to lower the trim down some in turns and when taking off when I do this, but should result in going faster.
Good, well made 6" manually adjustable jack plates for the motor you have can be had on Ebay for as little as $185.00 with shipping. Only issue to watch for is that your steering and control cables are long enough for the additional distance.
My experience and .02 anyway.
-- Jeff
