There is a different optimal Cp at legend and deep load displacements

At least for the "Super Fast Battlecruiser-Alternative Design", there are different optimal Cp's. At legend displacement of 34,339.9 tons, the optimal Cp is 0.61 with a Cm of 0.91. This produces a maximum speed of 37.8853 knots. At deep load displacement of 39,697.6 tons, the best Cp is 0.56, which produces a maximum speed of 36.7051 knots. The actual best speed with the designed Cp of 0.61 is 36.6468 knots, which is not significantly different. I need to decide if I am going to let the program design the Cp. My power curve calculation computes the draft at the displacement and form coefficients, so that is not a problem. I would need to use the resulting draft in stability calculations, as well.