: However, the resistance of fluid flowing by a kayak is VERY different than
: friction of two solid surfaces sliding. The two situations are
: fundamentally different, kinda like night and day different. In the fluid
: flow situation you are dealing with phenomona like laminar flow, turblent
: flow, boundary layers, wave making -- with controlling parameters like
: viscousity.

Not soooo different, I believe both of the relavant calculations require the term 'coeficient of friction' which affects the surface resistance component of the overall resistance. So if resistance is reduced and input power and other parameters are constant doesn't speed increase?

: But, like Brian, I am more than skeptical concerning
: attributing speed gains to graphite in the epoxy on one's hull (unless one
: is also sliding the boat over rocks as part of the speed trials,

I thought I made it clear in my description of hull preparation that a graphite/epoxy mix that is not smoothed is no faster than epoxy or varnish. It is the smoothing that reduces friction. Now, I personally believe, but cannot prove yet, that smoothed graphite has less friction than smoothed

I agree, I'd like to see empirical data on graphite vs. other hull finish, but we don't have it as yet. We're stuck with subjective anecdotes, like the testing I did before and after incremental sanding of my graphite/epoxy hull. Where I used a GPS and made multiple runs in opposite directions on non-moving water repeated on multiple days, but where my wattage output is unknown, although my paddling gates are familiar to me. Where the GPS saw 0.5 kn increase at cruising speed and the same increase at 95% max speed with a smoothed hull surface.