PNW Olson 30 Class Association

How to on the Olson 30

Burnish a Vinylester Bottom, like Baltoplate or VC-17

  1. Spray on 2 coats of Baltoplate and let dry.
  2. Wet sand with 400 grit sandpaper (knock off the rough spots only).
  3. Bronze wool polish the surface (I forget the wool grade recommended). [ed. Do not use steel wool, as any little flakes will end up rusting.]
  4. Finish by burnishing with a piece of hardwood that has had the end ‘fired’ - ie you take a piece of maple flooring, cut an angled tip on it. Then stick that tip into live coals (or hit it with a blowtorch) until it gets a layer of charcoal on it. Rub away the charcoal by rubbing against a hard and smooth surface (like a piece of slate). Then use that on the BaltoPlate.


The wool and the burnishing should only be done in Fore/Aft motion.

The idea that you only need to polish the first 6 feet of hull and forward 1/3 of the keel because of Reynolds numbers - is an old wives tale. It is based on drag models scaled up from hull testing in drag tanks. Turns out that Reynolds numbers don’t scale that way - especially in ‘surface boundary’ environments.

We found on the J-24, that going to 1600 grit (on a vinylester epoxy bottom) for the whole keel and rudder, and the forward 2/3 of the boat, made a noticeable difference.