Betsie Bay Kayak was the company that did that. They installed them above the deck as usual, but they now offer the under-deck mounting for $100 more. Their site doesn't yet show their new 18'x20.5" kayak or the under-mounted system, but here's the picture of the Beckson pry-out hatch.

Dean

: Hi Ross, I saw somewhere (where, I can't remember) that someone (whom, I
: can't remember) installed Beckson hatches. The rigid Becksons were
: installed below the surface of the deck, and the cutout piece was glued to
: the Beckson lid. All you saw were the small finger holes and the outline
: of the hatch. I think I might try that if I ever build a flat-decked boat.

: Happy Building, Shawn