Hey Dog: if you have a composite boat, better to invest time/$ in keeping the gel coat on the hull side in good condition - not pristine, we all use our boats, but avoid big gouges and scrapes.
the less uniform the surface the more drag. Wax won't overcome deep gouges and scrapes. In fact, if the wrong wax is applied, or any wax applied too thickly, more drag results.
For most of us chugging along at 3.5-4.5 mph, wax makes no difference anyway.