: Of course.

: There really isn't a "normal" size, per se, but 4" or so seems
: to be pretty common.

: Some people use thin walled PVC pipe glued or glassed in place. Some are made
: from molded fiberglass. There's no reason one couldn't be constructed of
: wood strips and 'glass. The shape doesn't have to be tubular. Fiberglass
: knee tubes are typically a half tube or rounded V shape. When glued to the
: deck, they form a tube. If you shape your knee tube correctly, all you
: need to do is pad it on the sides and you have solid knee braces.

: It certainly can, if you desire dry storage in the cockpit. The 4" round
: Kajak Sport hatch seems to be popular for this application. It's also
: possible to have access from the outside, so you don't need to pop your
: spray skirt to access the contents of the tube. The problem is that this
: might interfere with deck bags, chart cases, etc. on the deck.

: It's been discussed here before, but not for a while.

: You're welcome. I hope it works out for you.

Many thanks - I really appreciate the input. My mind is already working overtime on the possibilities and variations.