The Ultimate Guide To Replacing Portlights In Your Boat

Replacing the portlight in your boat is a straightforward process that can be completed in a single day. Portlights are square or rectangular windows on the exterior of a vessel, and portholes are smaller, round windows. The installation process for both is similar, and the components that come with these windows are generally the same. Before you begin, you'll need to find new portlights. If your portlights are round, oval, or rectangular, they are likely a catalog item originally supplied by a hatch-and-portlight manufacturer. If your boat's manufacturer is still in business, their customer service department may be able to tell you who made the original windows. If you can't find an exact match, you can either modify the opening or opt for custom manufacture. When you have your new portlights, the first step is to remove the old ones. You'll need to remove screws, cut the caulk, and use a braided wire or guitar string to take out the window. Then, you'll need to clean the surface and prepare the opening for the new portlight. This may involve filling in unused fastener holes and making adjustments to the cutout. Finally, you can install the new portlight, using sealant to ensure a secure fit.

Finding replacement portlights

Identify the Manufacturer

If your boat is still in production, you can contact the manufacturer's customer service department to find out who made the original portlights. This can make it easier to locate replacements.

Check Standard Sizes

If your portlights are round, oval, or rectangular, they are likely a standard size and can be found in catalogues from hatch-and-portlight manufacturers such as Beckson, Bomar, Gebo, Lewmar, Moonlight, Goiot, Taylor, or Vetus. Even irregular portlights may be shared across multiple boat models and available as off-the-shelf items.

Measure and Search Online

If you can't find an exact match, taking measurements and searching online can help you locate a suitable replacement. Keep in mind that enlarging the opening for a new portlight is typically easier than reducing its size.

Custom Manufacture

If you can't find a standard portlight that fits, consider custom manufacture. Contact small manufacturers in your area or larger companies like Bomon or Vetus that offer custom-made portlights. This option may be more expensive but can ensure a perfect fit.

Surface-Mounted Portlights

If appearance is not a priority, surface-mounted portlights made from plexiglass or acrylic are a cost-effective option. They are screwed directly to the hull sides and can be a straightforward solution, although they may alter the look of your boat.

Enlarge Existing Cutouts

If you're comfortable using power tools, you can enlarge the existing cutouts to accommodate bigger or differently-shaped off-the-shelf portlights. This option offers more variety but will significantly change the look of your boat.

Custom-Made Portlights

If you've found a great deal on portlights that are slightly too small, you can have them custom-made to fit the existing apertures. Companies like Bomon and Vetus-Maxwell can create framed portlights to your specifications. You'll need to provide them with templates of the openings, measurements, and details about the frame and interior trim.

Removing the old portlight

Step 1: Identify Fasteners and Remove Them

Old portlights may be screwed, bolted, clamped, or glued in place. Identify the type of fastener used and remove them accordingly. If the flange and/or trim ring exhibit fastener heads, remove them. If the fasteners are corroded, use the largest available driver that mates perfectly to avoid damage. A hand impact tool can also be useful for freeing old marine fasteners.

Step 2: Separate the Flange from the Boat

If the flange is sealed with a gasket, use a stiff putty knife to gently pry it away from the boat. Work your way around the window, using a second wedge to maintain the separation as you go. This step may require a combination of cutting and prying, especially if sealant was used during installation.

Step 3: Cut the Sealant

If the old portlight was installed with sealant, you will need to cut through it to release the window. A single-edge razor blade is the best tool for this; start with the blade in a holder for safety, then switch to a blade without a holder for deeper cuts. A carpet knife is another good option for safety. The safest cutting method involves attaching dowel handles to a 15-inch length of thin braided wire or fishing line and sawing it back and forth in the initial knife cut. Use shallow wedges behind the wire to allow deeper penetration.

Step 4: Remove the Portlight

With the sealant cut, gently pry and wedge the portlight out. If the seal is with polyurethane, you may need a chemical agent like DeBond Marine Formula to assist in the removal. Be cautious and patient during this step to avoid damaging the boat or the surrounding area.

Step 5: Clean the Surface

Once the old portlight is removed, clean the entire surface thoroughly. Scrape away any remaining gasket or sealant material with a sharp plastic blade, then buff with a Scotchbrite pad, and finally block-sand with 180-grit paper. If the old sealant was silicone, pay extra attention as it leaves behind a residue that prevents new sealant adhesion. Use a xylene-saturated rag to wipe down contaminated surfaces, then blot and wipe clean with paper towels. Ensure all residue is removed before proceeding.

Step 6: Repair and Prepare the Surface

Examine the cutout edge and address any issues. Fill unused fastener holes with a stiff epoxy paste and make any necessary repairs to the wood core or interior wood liner. Fair your filled holes and corner adjustments to ensure a smooth surface for installing the new portlight.

By following these steps carefully, you will successfully remove the old portlight and prepare the surface for the new installation. Remember to take your time and work meticulously to avoid damage and ensure a proper fit for the replacement.

Preparing the opening for the new portlight

Now that you have removed the old portlight, it is time to prepare the opening for the new one. The first step is to remove any remaining gasket or sealant material from the opening. Use a sharp plastic blade to scrape away the old material, and then buff the area with a Scotchbrite pad. Finish by block-sanding with 180-grit paper.

If the old sealant was silicone, you will need to take extra steps to ensure that no residue is left behind, as this can prevent new sealant from adhering properly. After scraping away the silicone, wipe the area with a rag saturated in xylene, and then blot it clean with paper towels. Be sure to use plenty of fresh paper towels to avoid spreading the contamination. Once the surface is clean, mist it with water; if the water beads, continue sanding until the water sheets.

Next, examine the edge of the cutout for any damage to the wood core or interior wood liner and make any necessary repairs. Fill any unused fastener holes with a stiff epoxy paste. The corner radii may also be crude or inaccurate, so use the epoxy paste to smooth and shape them as needed.

Before installing the new portlight, it is important to test the fit. Many portlights have a rubber gasket on the outside flange that helps to seal the window in place. Make sure that the mounting surface is flat and that the window fits snugly, with a gap of less than 1/16 inch around the perimeter of the flange.

Finally, choose the appropriate sealant for your new portlight. Butyl tape is a good option for mechanically fastened portlights, while a curing liquid sealant is necessary for portlights that will be bonded in place. If you are using liquid sealant, attach small spacers to the underside of the flange to ensure a uniform gasket. Just before applying the sealant, wipe both the flange and the boat with alcohol to remove any oily residue.

Sealing the new portlight

Select the Appropriate Sealant

Before you begin sealing, it's important to choose the right type of sealant. Silicone sealant is a popular choice for portlights, especially for framed windows, as it has strong adhesive properties. For surface-mounted portlights, consider using a stronger variety of silicone, such as Dow Corning 795 Silicone Building Sealant, which is typically used for attaching exterior glass to high-rise buildings. This type of silicone provides a stronger bond without costing more.

Surface Preparation

To ensure a proper seal, the mounting surface of the portlight and the surrounding area on the boat must be clean and dry. Remove any traces of old sealant, gasket material, or contaminants. Use a sharp plastic blade to scrape away any residue, then buff the surface with a Scotchbrite pad. Finally, sand the area with 180-grit paper to create a smooth surface for the new seal.

Test the Fit

Before applying any sealant, it's crucial to test the fit of your new portlight. Dry-fit the window without the gasket and ensure that the gap around the perimeter of the flange is less than 1/16 inch. The window should slide into the opening smoothly without binding. An ideal clearance all around is about 1/16 inch.

Apply Sealant to the Flange

Take your chosen sealant and apply a generous amount to the underside of the flange. You can also place small spacers at each corner and additional ones every 10 inches to ensure a uniform gap. The spacers should be about 1/8 inch thick and can be cut from plastic or hard rubber. Before applying the sealant, wipe both the flange and the boat surface with alcohol to remove any oily residue.

Install the Portlight

With the sealant in place, carefully align and install the new portlight, following the manufacturer's instructions. If your portlight uses screws or fasteners, tighten them incrementally in a crisscross pattern to ensure even pressure. It's important to apply enough sealant so that it squeezes out from the entire perimeter of the portlight.

Remove Excess Sealant

Once the portlight is securely in place, you will notice excess sealant around the edges. Allow the sealant to cure for several hours or as recommended by the manufacturer. Then, use a plastic blade to trim away the excess sealant, creating a neat finish.

Final Checks

After removing the excess sealant, carefully inspect your work. Ensure that the portlight is securely sealed and there are no gaps or cracks that could allow water to enter. Test the window for proper function and ensure it opens and closes smoothly if applicable.

By following these steps and paying attention to the details, you can effectively seal your new portlight, ensuring a watertight and secure installation. Remember to refer to the specific instructions provided by the portlight manufacturer, as there may be slight variations in the installation process.

Finishing touches

Now that you've installed your new portlight, there are a few final steps to ensure a secure and long-lasting installation.

First, check the fit of the portlight by gently pushing and pulling on it to ensure it is securely in place and doesn't shift or move. If there is any movement, you may need to apply additional sealant or adjust the mounting surface.

Next, inspect the seal around the portlight. Ensure that the sealant has filled all gaps and there are no air bubbles or cracks. Use your finger or a tool to smooth out any uneven areas and create a neat, continuous bead of sealant around the perimeter.

If your portlight has screws or fasteners, make sure they are all tight and secure. Follow the manufacturer's instructions for torque specifications if provided.

Finally, clean the portlight and the surrounding area with a mild soap or boat cleaner to remove any dirt, dust, or residue from the installation process. Rinse thoroughly and dry with a soft cloth.

With these finishing touches complete, your new portlight is ready to provide clear visibility and enhance the appearance of your boat for years to come.

Frequently asked questions