Perhaps I'm being dense, but I don't see how a prop, no matter how badly matched to the engine and boat, could be causing this problem.
The only things that influence the underway balance of the boat are its hydrodynamics and the fore and aft weight distribution. If you are motoring at the same speed and the boat floats on her lines at rest, i don't see why there should be a big difference in her attitude. The boat requires the same thrust to achieve a given speed, and cares not what is driving it... sail, well matched prop or poorly matched prop. The flow around the hull
, and the waves that it generates are the same (not taking into account heel angle which is not a factor when motoring).
Weight distribution could have some effect, but the amounts you describe seem inconsequential. Having a couple of crew members wandering about the deck
would be much the same...
So, I'm forced to ask: are you really sure that it is squatting far more than before at the same speed? Some squat in a displacement hull
is normal as boat speed increases, and I'm wondering if this is more of a perception discrepancy than a physical one? I mean no disrespect in this, but I'm baffled by the situation as described.