Thought I would start a new thread on this one since it the knowledge might benefit someone else.

I added a 6" setback plate to my Xpress XP hull last weekend. Had to set the motor up using the bottom mounting holes on the motor to get the prop height I was told to shoot for initially without maxing out the plate itself.

Upon assessing the whole thing while setting the prop at the recommended starting point it seems like I've lost a good bit of trim range. It just appears that I can now tuck the motor a lot more than I could before, and run out of positive trim after only a little bit of trim-up.

Is this normal?

I know tapered shims can be installed to bring some of that trim back, just curious if this is required very often?

Simply setting the motor back a few inches and raising it vertically doesn't seem like it would have that effect, in theory. But the actual geometry seems to, at least appear to have strayed from that theory. Still waiting on my water pressure gauge to arrive before I will be testing it, just wanted to see what the guru's think before I take it out only to discover I'm having a problem that is common to the mods I've made?

Any input?

When I had my Bob's JP installed on my Seaark, my mechanic moved the motor to the second hole. The angle of the back side of the JP is the same as the transom, so I wouldn't think that should affect trim function. I have not noticed any adverse effect on mine. That said, normal trim on mine is a little bit above all the way down. My boat is heavy in the rear and it helps to control porpoising.

I'll try it the way it is and see, and maybe it's an optical illusion, but it appears that the motor is tucked a lot more than it was before adding the plate.

motor is actually lower, givin' that impression...

like he says. movin' back can lead ta rasin' tha motor as said... angle doesn't change with 99% of tha jp''s..........

addin' tha jp ya gotta start over on tha set up like on Josh's (steve's) custom/performance props website

from a guy that makes jack plates for a living.

the part of the plate that mounts to the boat is the same degree as the part that mounts to the engine.

it doesn't effect the actual trim angle (more or less).

now.. that said. i do this quite often.. customers request a certain amount of negative tuck and some request positive.
if that was done on the plate your purchased, then yes.. you will loose trim angle. (tucked under).

make sense?

Most transoms have an angle to them--They are not straight up and down. That said when the JP was added the angle did NOT change (As Steve Said) it just pushed the motor deeper. Now you have the wonderful opportunity to find that sweet spot all over again.

I understand the theory, and like I said above it may be just an illusion. I will test it the way it is, just thought I'd ask. I got my answer. Thanks for the input.

Measure the distance between the two surfaces at the top and the bottom and they should be parallel.

Mystery solved.