: I've read some about this. It seems that the concept is to change the
: friction from water/hull to water/water, by dragging a layer of water
: along with the boat. I think it's an interesting concept. Whether it would
: really help a kayak is debatable, but it seems to be pretty debatable on
: million dollar yachts.

You may debate if you wish, but the laws of mechanical similitude insist that what works on one boat will work on another to some degree regardless of size. However, I would conjecture that the technique you speak of is highly dependent on using a specific material applied to the wetted surface area prior to the sanding.

In my experimentation with graphite and hull smoothing I have (subjectively)test paddled my kayak smoothed to 220, 400, 800 grits in order to see if there was a less laborious method available to achieve the performance boost I enjoyed when sanding to 2000 grit. My perception is that the 'placebo affect' is inversly proportional to the grit of the sandpaper.

: Another insteresting material is bottom paibnt with teflon, which is designed
: to be polished. The teflon is more so that speed stealing growth cannot
: stick to the hull, rather than direct loss of friction, but it is
: interesting anyway.

Teflon has about the same friction coeficient as graphite (0.04) but without the inherant lubricity. Non-stick kayaks, pretty slick!