DaySailer.org Forum

The "secret" about not waxing the bottom, is not a secret. A smooth fair bottom helps the creation of a "boundary layer" of water that clings to the bottom and releases the surrounding water with the least amount of friction and surface tension. Bumps, scratches, and deformities to the hull, disturb this layer of fluid and cause it to part from the hull prematurely causing eddies, swirls and back suction. Wax, sheds this layer of water, and breaks it up as it tries to form, so is actually slower. Boats with smooth fair bottoms and foils can be as much as 10% faster over the same course, given that all else is equal. 320 grit, and VC17 or Baltoplate, rolled on or sprayed, and burnished with 00 grade bronze wool is about as good as you can get your bottom.

Michael:
Finally, an adequate rationale for not waxing. The "boundary layer" explanation makes a lot of sense. Over the years, my hull has been religiously faired by high-grit wetsanding, which I've continued as the latest owner. This has been crucial to keeping the boat competitive. However, because of this treatment, the gelcoat is wearing thin. I do a combo refinish by alternating 500-1000 grit wetsanding with automotive spraypaint that happens to match the gelcoat in color. That way I don't have to coat the entire hull, which becomes a whole other maintenance issue.

You've piqued my interest, though, with "320 grit, and VC17 or Baltoplate, rolled on or sprayed, and burnished with 00 grade bronze wool"

I'll look around for these coatings, but maybe you could describe them for me?