How to Make Your Own Swim Platform for a Boat

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Boating and swimming often go hand in hand, especially when the weather outside is sweltering. Jumping off the boat is the easy part, but getting back on can be a huge challenge for both adults and children. This is especially true in the case of a vessel with no swim platform or ladder. Boat owners who want their passengers to be able to enjoy swimming more often can buy a pre-made platform or build one with a personal touch.

Items you will need

  • Measuring tape

  • Marking pencil

  • Paper

  • Level

  • 8 pieces of 2x4, 6-inch lengths

  • Decking screws, 3 inches and 2 inches

  • Power drill with wood and metal drill bits and screw heads

  • Marine oil finish, 1 quart

  • Paint stirrer

  • Paint brush

  • 8 1/4-inch gauge hex bolts (6-8 inches long) with washers and lock nuts

  • Marine goop

  • Socket set

  • 1x6 and 1x4 sections of hard wood like mahogany, varying lengths

  • Circular saw

  • Saw horses

  • Waterproof wood glue

  • Carpentry clamps

  • 6 small metal corner bracket kits with short screws

  • 7/8" ss tubing

  • Sabre saw with metal blade

  • Hammer

  • Vise

  • SS screws

Step 1

Measure the back wall of your boat with your measuring tape. Write down the wall-to-wall distance starting at the height you want the platform to sit. For outboard engines, you will have to work around the motor. Take into account the movement of the motor during steering and trim adjustments when you measure. Use the level to trace a line across the back boat wall with the pencil.

Step 2

Screw two of the 6-inch 2x4 lengths together with decking screws. Make four solid blocks with this method. These will be used for mounting points. Screw from front to back and back to front to ensure a solid connection. Drill two equidistant pilot holes for the bolts through each block. Paint each block with a complete coat of marine oil finish and let it dry.

Step 3

Place the first block against the back wall of the boat, aligning the top surface of the block with the level line. This first block should be placed least an inch from the side of the boat. Drill through the pilot holes into the back boat wall. Insert the bolts into the pilot holes and smear some marine goop around each screw end inside the boat. Place the washers on the screws and use the socket set to fully tighten each nut. Attach all other anchor points the same way.

Step 4

Build your deck frame using 1x4 lengths of mahogany. Measure and cut 10 strips of wood to make the frame. The six pieces for the front, back and middle lengths will be 8 inches less than the full length of the deck. The four side pieces will be the full width of the deck. Each measured and cut 1x4 length should be glued to another board that is the same length so there is absolutely no overlap. Use the carpentry clamps to make a strong, lasting seal. Lay the glued blocks out on the floor and make a tight rectangle, using the level to ensure structural integrity.

Step 5

Screw the corner brackets into place on the frame to connect the front, back and middle lengths with the sides. Paint the entire frame with wood finish. Cut the 1x6 pieces into equal lengths for your decking and paint each plank with marine finish. Align your first decking plank an inch out from the frame's back edge. Drill pilot holes through the decking where it intersects with the frame sides. Screw the decking to the frame with the 2-inch screws. Break two small pieces off the paint stirrer for spacers and put them between the first and second plank. Drill new pilot holes and secure the second plank with the 2-inch screws. Repeat these steps with each new plank until you get to the final piece.

Step 6

Position the completed deck snugly against the back wall of the boat, resting it on your mounting blocks. Drill pilot holes through the back frame piece. Secure the back frame length to the mounting blocks using the 3-inch screws. Cut 4 equal lengths of the SS tubing and use the hammer and vise to pinch the ends. Bend the pipe to give one end an angle for screwing to the boat and the other end an angle for screwing to the bottom of the swim platform deck. Drill a pilot hole through the center of each flattened end. Secure the tubing to the platform with the SS screws first. Dab some marine goop on the SS screws that will go into the boat wall and secure all these ends to the boat.