Do-It-Yourself: Installing A Swim Platform

by Steve Noury

Most newer recreational boats are equipped with swim platforms, but a lot of older models tend to lack this feature. Safety should always be the most important issue, and trying to keep children away from the outdrive unit and propeller when anchored can be a challenge.

A must-have remedy for this situation is a custom-fit platform from Swim Platforms Inc. (www.swimplatforms.com). These platforms give your boat the look of a factory fit and finish, in addition to protection from the potential hazards of swimming near an exposed outdrive unit.

Step 1

You’ll need some basic tools to complete this installation — a drill, a set of drill bits,a counter-sink bit, a ratchet with sockets and an extension, and an Allen wrench. Also, be sure to have some marine- adhesive caulking, such as 3M 4200, and some anti-seize compound for the stainless-steel bolts and nuts. Lastly, you’ll need some wooden blocks and some 2x4 boards to support the platform up to the hull, and a little acetone to clean up excess caulking. First, remove the engine’s compartment cover, rear seat backs and rear seat back support so as to gain access to the boat’s interior transom area. Inspect all areas inside the transom to make sure your pre-drilling won’t do any damage to the components. Also, remove any existing ladder and grab handles that have been previously installed onto the transom.

Step 2

Next, the platform needs to be placed flush onto the hull below the gunwale molding. Remove a screw from the inside of the vinyl trim, then pull it down on both sides where it contacts the transom. Since the platform is custom- molded to the boat’s rear profile, it’ll center itself. Trim the outdrive down slightly, and place a few blocks of wood on top of it. Carefully place the platform on top of the blocks of wood, and raise the drive up slightly to hold the platform up to the hull. Cut a few 2x4 boards, and use them as legs for the platform, then level it from front to back. Next, drill four holes in the outdrive area — make sure you select an unobscured spot for the first hole. Drill two holes on each side of the outdrive within the well area. Insert a bolt temporarily into these holes to limit any movement. Don’t caulk or tighten any bolts yet.

Step 3

Now it’s time to drill three holes on the port and three holes on the starboard side of the transom. In this example, both the grab-handle holes are reused to mount the platform onto the starboard side. The port side of this particular Chaparral 2135 BR is a little harder to work with, due to the drink cooler that’s molded into the boat’s rear. In such a situation, take measures to ensure you don’t run the drill through the hull and continue into the cooler. There should be a gap large enough to get the washers and nuts between the transom and the cooler. Now, with all of the holes drilled, you can remove the platform. Lightly countersink all holes about one-sixteenth of an inch. This process will prevent the washers from squeezing out all the caulk, and it’ll improve the seal. Finally, apply a circle of caulking to the transom and the platform around each hole drilled.

Step 4

Reset the platform to the transom, and insert the four center well bolts, using the caulk. Use washers on both ends of the bolts when you secure them. Install both the port and starboard outboard bolts with washers, and then install the two downrod supports. The short downrod is used between the ladder frame. The top of the rod will be attached with one countersunk Allen head bolt and one panhead screw. Pre-drill from the bottom up, and then countersink from the top down — do it just enough to get the head flush with the platform’s top. The bottoms of the rods will be attached with two lag screws. Pre-drill and countersink the holes. Use caulking between the transom and rod tab, on the hole and screws, and tighten. Lastly, cut the trim to size, and then attach it to the platform.