Measure the total floor space in the boat's salon or cockpit, using a measuring tape. Measure the length and width of each of the seating banks -- the bench seats and their bases -- to ensure that they will fit.
Move the lounge seats into position. Remove the seat cushions. Locate the right-angle mounting tabs inside the lounge seat base. Outline the mounting holes on the boat's deck, using the mounting tabs as a template, with a china marker.
Drill 1/8-inch pilot holes in the deck at the center of each of the marked mounting holes. Drive 1/4-by-1 1/4-inch self-tapping screws through the mounting tabs and into the deck.
Reposition the seat cushions on the lounge seat bases.