I have applied graphite/coloidal silica (same as cabosil)/epoxy from the shear down on my AT14 for the last two years. I typically use 2 tablespoons in my 4 ounce mix (3::1 hardener), though I have tried much higher ratios. Initially I did it for anti abrasion purposes but was dissappointed that I saw only degrees of improvement, but yes there is definately a reduction in gouging and the boat glances off from most impacts. The bottom still required routine inspection and repair of deep gouges.

The second year I incrementally sanded the graphite to an unearthly frictionless slickness and enjoyed increased speed (0.5kn @ speed/length ratio of 1.7 on 12.4' WL, paddling effort is subjective, your mileage may vary) and agility. Resistance wise graphite/epoxy acts more like epoxy until you start smoothing it (I wet sanded 220, 400, 800, 1200, 1500, and 2000 grits, then compounded and waxed). First, you have to be more carefull strapping the kayak on top of your car because now there is no friction between the minicel pads and the hull. Then, when you lay it down on a rocky or pebbly beach it will slide into the water by itself. Sometimes a frictionless surface can get downright frustrating! But then in the water... Got Glide? Turns and catches waves easier too.

The first problem with graphite is the black gets on everything unless you have waxed. The second problem is that later when you add a layer or do a repair there is no chemical bond to rely on and since graphite is itself a lubricant the mechanical bond is weak. So, when you hit a rock the area of the strike or gouge will chip and delaminate. By the way, graphite powder is just pencil lead dust, and its not black, its grey like a pencil (it looks black when suspended in epoxy, before any sanding, and wax makes it darker too.

I would say that racer ought to use smoothed graphite, or a paddler that has trouble keeping up with a group, or if you need to coax a few more miles per day out of your boat. But in general it is probably a lot easier to maintain and repair some other substance.

I am not planning on using graphite on my next build (S&G NH), its just too messy and hard to maintain. I'm probably going to paint the hull black with some marine paint that doesn't require a positive pressure mask and leave the deck bright. The lay-up will be 4 oz S-glass doubled on the football. I actually bought Dynel for the football but I hear it soaks up epoxy and is therefor heavy. I believe the S-glass is even lighter than carbon fiber since CF retains epoxy as well (unless vacuum bagged or autoclaved).