The neatest trick I've run into for helping to sand a truly fair surface is Vaclav's, shown on his One Ocean Kayaks website. It's the use of marker to show unresolved low spots, and is explained fully at his link:

http://www.oneoceankayaks.com/Wshophtm/Shop13.htm

A lurking newbie still getting together the Stuff for a Spring Run, but I plan on using the technique when we get to that point.

Craig

: The first coat of varnish will make it shine. However, the varnish will not
: provide any filling and will actually make the surface imperfections more
: obvious. Wetting the hull will give you and indication of how the finished
: hull will look (you should wash the hull anyway before the first coat of
: varnish). Any imperfections you don't want to live with must be filled
: with epoxy and sanded smooth. Using a fairing board will produce the most
: wave free surface. RO sanders should be used flat as sanding with the edge
: of the pad will create crescent shaped dips but will not equal the smooth
: curves of a fairing board. You should sand the epoxy with a min of 100
: grit before varnishing 220 would be even better. See Green Valley's
: Builder's Notes.