How to Build a Boat Dock Gangplank

Cut eight 1x6 planks to the desired length of the gangplank, using a circular saw.

Cut one 4x4 to a length of 46 inches, for each three ft. of length for the gangplank. Cut two additional 4x4s to a length of 72 in. to secure and stabilize the gangplank.

Pre-paint or pre-treat with a lumber waterproofing treatment all surfaces of all the planks and lumber before assembling the gangplank. Allow the coating to cure thoroughly before assembly.

Clamp one end of the 1x6 planks edge to edge with carpenter's clamps, keeping the ends of the 1x6 planks even. Slide a 4x4 x 72 in. piece under the 1x6 planks. Use a hammer and nails to attach one end of each of the 1x6 planks to one of the 4x4 x 72 in. pieces, nailing downward through the 1x6 planking. Repeat for the opposite end of the 1x6 planking, with the remaining 4x4 x 72 in. piece.

Clamp the center of the 1x6 planks together, slide the remaining 4x4s under the 1x6 planking, spaced three ft. apart. Nail the planking down on to the 4x4s.

Add the metal handrails to the sides of the gangplank using the hardware included with the handrails.

Caulk all nail holes and all nail and screw heads on the gangplank with marine silicone caulk, after it is assembled.