Boaters Can Install Opening Ports Themselves
by Matt Reed

Installing a plastic, cabin-mounted opening port can be simple if you follow a few basic steps and take advantage of some helpful hints. The following procedure is for a new installation in a flat, single-layer wall with a 3/8” or greater thickness.

Choose the location for the port and tape the outer trim ring to the outside of the cabin wall. Make sure there is adequate space for the installation between the deck and the cabin top on both the inside and outside cabin walls. Drill two pin holes near the top corners of the ring, insert pins in the holes and place the ring on the pins, finished side out.

Trace the inside of the ring on the wall with a pencil. Drill several small holes inside the traced area close to the pencil line to allow starting a sabre or key hole saw, and cut on the outside of the pencil line.

Place the window in the hole and inspect it from the outside to make sure there is at least a 1/8” gap around the port for sealant to account for thermal expansion. If the window is tight, use a file to enlarge the hole. To help keep the port centered, use kitchen matches or small pieces of electrical wire as spacers, but be sure they can be completely sealed over. Also, the port’s spigot, which is the collar that passes through the wall, should protrude about 1/4” past the outside of the wall so that the spigot will be flush with the trim ring. This provides proper water drainage.

When the port is centered, the 10/24 pan head bolts and 3/8”-shank barrel nut fasteners can be installed. It’s best to purchase extra bolts, both 1/8” longer and 1/8” shorter than the wall thickness, to accommodate any variances in wall depth. Drill through the inside port frame and the cabin wall from the inside with a 3/16” bit.

Change to a 17/64” bit and broaden the holes on the outside of the wall to a depth by placing a piece of tape 3/8” from the bottom of the bit and do not drill past it. Next, carefully use a 1/2” bit to taper the tops of the holes. This allows the heads of the fasteners to be flush with the cabin wall.

If the spigot sticks out past the trim ring, you may want to trim it off flush by tracing a pencil mark around the spigot and cutting it with a fine tooth saw. Also, wipe the wall area outside of where the trim ring will be mounted with liquid dish soap. This prevents excess sealant from sticking to the wall.

To install the window, insert the bolts from the interior and dab a small amount of silicone into the fastener holes from the outside, leaving room for the barrel nuts. Install the fasteners and tighten them fully with a Phillips or slotted screwdriver.

Fill the space around the spigot completely with silicone. If needed, use a tongue depressor or popsicle stick to press the sealant into the gap. Then, lay a generous 3/8” single bead of silicone onto the underside of the trim ring, ease it onto the spigot and press it firmly onto the wall around the spigot. Do no clean up excess sealant until it has cured. Usually, 2 to 3 days in the summer or 1 week in low humidity is enough time. With a single-edge razor blade, remove excess caulk from around the trim ring. Do not scrape the ring. Use a fingernail if necessary.

Following the above installation steps will help accomplish several objectives. You save money and time on labor. You know how the job was done and what is involved if alterations are needed. And it’s a great reason to get out and use your hands.