Steve,

Are the dimensions you gave the underwater area of the board, or the total length (including the part iniside the hull)?

What are the class dimensions of the underwater area of the board? Is there a thickness restriction? What about the shape of the trunks? Will the new boards have to fit through the old trunks?

The daggerboards need to be effective over a broad range of conditions, thus some compromise has to be reached on the foil section and the plan form (rake, tip, aspect ratio). You can't be optimum in all conditions.

Of course, you could just build a different set of boards for each combination of wind / waves