I replaced the sole in my old 28' yacht using the old plywood
sole and laid a 6mm layer of Tasmanian blackwood over the top using west as the adhesive
and plastic spacers to get the gap. To get the "Holly" look I then used a mixture of west resin & microlight filler making a very thick mixture trying carefully not to get any air bubbles in & used a squegee to force the mixture into the 6mm groove.
Once dry, sanded & finished with a few coats of International 2 part polyurethane
. Very satisfying result IMHO.
My new (to me) 38'er has a very ordinary looking plywood
veneer sole - I will attempt to refinish this winter, but if it is too far gone, I will probably do the same....