: 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?

Don't be confused by terminology. The term "coefficient of friction" used in the case of sliding contact between two solid surface is a very different creature than the that used in fluid dynamics, also often referred to as a "drag coefficient". Just because graphite reduces resistance in the solid case does not mean that it is slippery in the fluid case.

: 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 doubt I would have jumped into the discussion if there was a claim of increased speed attributed to polishing a kayak's hull (though I'd still would be doubting a 1/2 knot increase from polishing). What triggers my skeptic-o-meter is attributing the increase to the presence of graphite -- especially with data that is only anecdotal.

: 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.

Despite my skepticism, it is cool you are going soo much faster (and placebos have been scientifically proven to work in certain situations) ...

-John D.