Since April last my bottom has been coated with a variety of materials of different smoothnesses; epoxy, varnish, epoxy with graphite, epoxy with graphite and colliodal silica, and even varnish with graphite (works good!). Sometimes burnished with a 3M pad or wet sanded, but I have to tell you about my most recent experiment.

I was never really after speed, I wanted abrasion protection. I don't mind the scratches but I was finding at least one deep scratch a week (20-40 miles). I mean a scratch that needs attention or the wood will soak in that slow black death. So every time I find one of these I add a layer of epoxy with graphite and silica (cabosil), and it worked, I rarely see worrisome scratches anymore. Unfortunatly the kayak gained 10 pounds (now 46lbs). So anyway, the bottom was covered in this unsmoothed epoxy mixture when I decided to see what kind of difference in performance I would feel if I really smoothed the surface. I wet sanded 220, 400, 800, 1200 grits and then compounded and paste waxed. My usual put-in spot has a very low slope with 1/2" to 1 1/2" gravel and some scattered larger rocks. When I put the yak down- as I let go of it- it slid down that near 0 slope and into the water like someone pushed it! No friction, good omen. Later, as I paddled and found the boat accellerating like never before I was surprised to find that my top speed went from 4.75 to 5.0, on a (12.74 LWL).

Also,one of the great things about graphite is its lubricity. When you hit a rock with straight epoxy or varnish finish that surface tends to 'grab' the rock back making any damage worse. The graphite makes the surface slip over the rock minimizing any damage. And it comes in any color you want as long as its black. No hard data on this but it is my guess that the graphite doesn't make the surface smoother, it gives you a finer texture so you can develop a smoother surface.

Different tack: From back in my sailor days I remember somebody getting caught making their boat faster by leeching a long chain polymer substance out pin holes in the fore foot- it promoted extended laminar flow!

Back on t'other tack: They sell a spray, seen it in a couple of marine stores, that boasts decreased friction when applied to hull surfaces. I don't know what is in it but you might want to seek permissiom from some fish friends before spraying chemicals on their house.