: I agree with Eric's solution. However, for those of us who can't/won't/don't
: want to go through such hassle, the crafty Finns from Kajak-Sport has
: developed a fantastic "mini-hatch" system. Instead of cutting an
: opening on the deck, and messing around with waterprofing, and worrying
: about hitting one's knees against some unfriendly sharp edges, and not
: getting sufficient storage space, etc. etc. etc., the Kajak-Sport
: "mini-hatch" system is easily mounted on the inside deck (thus
: no need to cut anything on the deck); is relatively large (over 21"
: long and about 10" wide in the front); has rounded edges (no
: "ouches"!); and, perhaps best of all, it is 100% waterproof
: (access through one of their world-renowned 4" hatch cover)!! Check
: it out for yourself on their web site below.

In addition to serving as storage, the Kajak Sport mini hatch also serves as a solid knee brace. It would seem fairly straightforward to construct something similar out of cedar strips and 'glass, with a Kajak Sport 4" hatch for access. This will allow you to custom size it for your gear and the knee position that you prefer.