[Bushwacker]

I used similar L-bracket scheme to mount my galley seat, except I used oversized thickened epoxy-filled holes in deck instead of the below-deck L-brackets. Seating area of the original Seafari deck has ~3/4" plywood core instead of 1/2" balsa core; I drilled 1/2" hole thru deck but NOT thru bottom layer of glass, and then filled with epoxy. I then drilled and tapped the epoxy for 1/4-20 machine screws, which hold better than tapping screws. Toughest test to date has been 185# guy in seat in 5-6'seas; seems solid so far.