: . . . .It seems that I should put
: more coats on the deck and gunwales for UV protection (maybe 3 topside and
: 2 on the keel), does that seem about right? . . .

Consider also the time that the boat stays in storage, as well as the amount of time that it is used. If you plan to store your boat outside, and upside down, then the bottom will get the full force of the sun for most of the kayak's life. In this case, you should put more on the bottom, and plan to revarnish every year or two.

Two coats should be fine with most materials. Anything more than three is usually irrelevant from the standpoint of UV protection -- but that also depends on how thick the coats are, and how much you sand off between coats.
how good of a UV blocking material is in the varnish, and how much you sand off between coats.

:Also, the websites that the BB
: has directed me to have conflicting information about sanding between
: coats. 320-400 grit versus 150 - 180 grit, any thoughts?

For a good finish the 150 to 180 grit sandpaper is just fine. Use fresh sandpaper and don't use a lot of pressure. Your next coat of varnish will fill the tiny grooves left by the sandpaper and should level itself out. The finer grits of sandpaper are used by some people who want a slightly higher gloss finish. If you use thinner coats of varnish you might need to use the finer grades of sandpaper to avoid sanding through those.

Try using the 150 to 180 grit sandpaper and see if the finish satisfies you. If not, then just consider it a good base. You can always do the next layer with finer grit sandpaper and thinner coats if you want to. Decide where you want to stop. You can get obsessed with overdoing a finish on a boat if you are not carefull.

hope this helps.

PGJ