All the application of formula and theory is fine (and necessary) when applying it to a basic hull shape, but as we all know (or should know) sailing craft are always operating in a continually varying compromise situation between the actions of hydrodynamics, aerodynamics, and their interaction at the boundary layer as well as the effects of movable ballast, its relative position, total ballast weight, sail control, and the overall combined weight of the craft and of ballast.
So many variables, such difficulty in calculating and/or predicting mathematically or practically the combined overall effect in all/most sailing situations.
By the application of JUST the appropriate, two dimensional
Hydrodynamic formulae in the hull design without due consideration to a global formulation of all the other interacting effects that are always present when actually sailing, will generally not produce a very efficient craft. One noticeable example of a compromise design trend seen more commonly in recent years is of building more and more cats with greatly pronounced “tumble“ home in their bows combined with longer finer entry’s BUT still carrying more buoyancy low down in the bow area. Theoretically this should actually reduce their resistance to forward motion when the bows are driven deeper into the water rather than increase the “tripping” effect that bows that become wider at the deck display. This “trend” is not solely the application of hydrodynamics for the “theoretical” best hull shape as seen in a test tank or theoretical formulae applied situation, but mostly it is a practical application response to an unwanted effect when actually sailing. You may “back calculate” the effects of the tumble home in these designs to show why this is so, but why were their predictable effects “overlooked” for so long in the theoretical design of so many catamaran hulls?
My point being that to take in isolation just the theoretical “best” hydrodynamic hull form without compromise to all the other variables applicable to practical sailing, will invariably produce a craft that is generally “a dog”, or at the least no where near it’s optimum.