hydraulic jackplates

[lateralinfo]

i run a 40-foot center console engine with twin DF300AP suzukis mounted on seastar hydraulic jackplates. the engines are too long for the transom, that's why they recommended mounting the jackplates.
i feel that i am not using the full potential of the jackplates. i have been told that they offer many advantages in terms of trim, balance, fuel consumption etc if set up correctly with the engine trims.
can anyone shed some light on the fundamentals of hydraulic jackplates alongside engines trim? any information would be useful.

[Harper]

The fundamentals are basically the same as mounting the engines at the right height. Read moonlighter's sticky on engine mounting height and prop selection. FInding the best height for your motors using the hydraulic jacks will take some experimentation on your part and with the experience gained, you'll be more aware of where the best setting is. That best setting will also change with sea conditions. Following seas will require a different height than heading into the waves. But for simplicity's sake, the height of the motor with the anti-ventilation plate riding just on top of the water in smooth waters is what you're shooting for. You'll know if you adjust the motors too high. Another advantage of the jacks over a direct transom mount is that the motors sit back from the transom and the props are in "cleaner" water, increasing their performance. I also found with my jackplate that I now run with the engine trimmed much farther in than I did before I installed the hydraulic jackplate.

[lateralinfo]

so you're basically saying once i find the height, i don't change it anymore?
i was told i can balance the boat port vs starboard using the jackplates. is that true?
PS: i tried looking at the ventilation plate while on plane, it was skimming the surface at all different heights. am i doing something wrong here?

[Harper]

No, I wasn't saying that at all. The jackplate gives you much more flexability and allows you to optimize your motors' performance in varying conditions. What I was saying is that for best performance the same rules apply as finding the correct height for mounting you motor. The correct height for your motors in a fixed mounting position is a compromise when it comes to different sea conditions. The optimum height for SMOOTH water would be the same whether your mounting height was fixed or adjusted by the jackplate.Only in relatively calm waters do you not need to change anything. You find the right position of your jackplate for calm water and return to that same setting the next time you're in calm water. I lower it somewhat in following seas. I lower it somewhat in rough seas. I also often have to lower it to get on plane, then raise it back to the best level. You have to play with it and get to know how your boat responds to different jackplate heights under different conditions.

I have my doubts that you can balance the boat in the way you say you've been told, but I don't have dual motors. It's just my opinion. Try posting some pictures of the anti-ventilation plate while your boat is on plane. It will help to address you question.

[lateralinfo]

thanks a lot harper. very helpful. will post pictures next time i go out.