Pedestal Seating

• To mount a pedestal seat, like a tall captain's chair, you start by cutting a hole in your deck with a jigsaw.
  
  Most recreational boat decks are barely thick enough to support your weight. If you stand on one foot, you'll feel the deck "give." You can use a stud finder to find the stringers that support the deck where you want to put the pedestal seat. Once you find the stringers (they run lengthwise under the deck), a partial sheet of marine plywood secured between them will serve well as the base for the base of the pedestal, spreading the force of the seat's movement to the joists. Cover the surface of the plywood with marine adhesive sealant and set the piece of deck you removed back into place. Caulk around the edges with marine caulk. Drill mounting holes through the deck and the plywood and bolt the seat in place.
  
  

Bench Seating

• Whether you build the bench seat or buy it, you can find "L" brackets hardware stores or marine supply houses to hold it in place. As with pedestal seats, use a stud finder to find and mark the stringers in the area where you plan to put the seat. Set the seat in place and set the "L" brackets at points where you can screw the bottom of the brackets into a stringer.
  
  Once you have the bottom of the brackets attached to the deck, screw the back of the brackets to the seat base. Unlike with pedestal seating, you don't need to reinforce the deck, since the base of the seat is large enough to distribute the weight across several stringers.