Ok boat has INCO full hydraulic steering.

Wheel was a little off, SO i unbolted it and centered it.

then next time out was off again... haha SO my only conclusion is it will change it if you move the wheel with out power steering working?

Whats the deal? i know its a big rotary valve the wheel spins thus pushing fluid fom one ram to the other, but why does it change every start up?

You answered your own question with that statement... The two rams use the same fluid source, and when you rotate the valve it sends pressure one way or the other. The valve has no "center" and doesn't care where the wheel is pointing. The wheel will get off center in a hydraulic system no matter what (makes no difference if the engine is running or not) it's just the way they are!

SO stop trying to adjust it! Ok got it.

just seams once you had all the air pockets out of it there would be a center casue you cant keep spinning the wheel.. but that center changes every time.

Normal...thats why alot of guys with hydraulic steering use a steering wheel with the Y spoke in the middle..

there are internal bypasses in the helm that releave tiny amounts of pressure and fluid. after a time it is enough to offset the wheel.