Replacing Your Boat's Drain Tube: A Step-By-Step Guide

Replacing a drain tube in a boat is a common procedure, especially for older boats with corroded or broken drain tubes. The process involves removing the old tube, preparing the hole, and installing a new tube. This can be done using various tools and techniques, with some methods being more complex than others. The most important aspect is to ensure a watertight seal to prevent water intrusion and potential wood rot in the transom.

Removing the old drain tube

Firstly, carefully work from the outside of the transom. Use a sharp 1/2-inch chisel and a dead-blow mallet to crush the brass fitting inward until much of the tube is forced inside the drain hole. You can also use a screwdriver and hammer, working slowly around the rim of one side of the tube. Then, find a long socket wrench that matches the diameter of the drain hole. Place the socket in the hole from the outside and tap on it with the mallet enough to push the brass tube inward and out of the hole. You may need to stop and chisel away more of the brass before continuing to tap the tube out.

Next, check the condition of the wood core. If it is damp, give the holes a week or more to dry out. Keep them protected from rain or other moisture. Once dried, ream out the holes to a larger diameter. You can use a grinder to do this, but do it symmetrically and straight so as not to oversize the hole or change the angle.

Now, seal the wood with an epoxy resin. You can use a two-part epoxy resin, such as West System, and apply it with a brush. You can also use thickened epoxy and a syringe to inject it into the hole. If you want to use resin and flake to match the gel coat, first drill out the holes an inch deep and inject the resin with a syringe and a blunt needle. Then, clean up the excess with a putty knife and tape over the holes with packing tape to help give it a shine when dried.

Finally, if you need to remove screws, use a screwdriver to take them out. You can also try using a drill to remove them. Remember to seal up all the old screw holes with marine epoxy or sealant.

Preparing the wood core with resin

Step 1: Select the Appropriate Resin

There are three types of resins commonly used in boat building: polyester, vinylester, and epoxy. Epoxy resin is ideal for attaching cores due to its strong adhesive properties. However, you may choose the resin that best suits your needs and budget.

Step 2: Clean and Dry the Wood Core

Before applying the resin, ensure that the wood core is clean and free of any moisture or debris. Use a brush or cloth to remove any dirt or residue. If the wood has been exposed to water, allow it sufficient time to dry completely. This step is crucial, as any remaining moisture can affect the adhesion and integrity of the resin.

Step 3: Seal the Wood with Epoxy

Apply a thin coat of epoxy resin to the wood core. This step will help seal the wood and create a barrier against moisture. Follow the manufacturer's instructions for mixing and applying the epoxy. Use a brush or roller to ensure an even coat. Allow the epoxy to cure completely according to the manufacturer's instructions.

Step 4: Sand the Wood (Optional)

Lightly sand the sealed wood core to create a rough surface. This step will help the resin bond better to the wood. Use fine-grit sandpaper and sand in the direction of the wood grain. Be sure to wear a respirator and work in a well-ventilated area to avoid inhaling dust.

Step 5: Apply Resin to the Wood Core

Once the epoxy sealer has cured, you can proceed to apply the resin. Mix the resin according to the manufacturer's instructions. Using a brush or roller, apply a generous amount of resin to the wood core. Ensure that all areas are coated evenly. You may need to apply multiple coats, allowing adequate curing time between each coat.

Step 6: Final Cure and Inspection

Allow the resin to cure completely according to the manufacturer's instructions. This may take several hours or even days, depending on the type of resin and environmental conditions. Once cured, inspect the wood core for any air bubbles, cracks, or imperfections. Lightly sand any raised fibres or rough areas, and apply an additional coat of resin if necessary.

Remember to work in a well-ventilated area and wear protective gear, including gloves, eye protection, and a respirator, when working with resins. Always follow the safety instructions provided by the manufacturer.

Sealing the wood with epoxy

Prepare the Wood Surface: Before applying epoxy, ensure that the wood surface is clean, dry, and free from any moisture. If there was previous water damage, remove any rotted wood and repair the affected area. Sand the surface to create a smooth base for the epoxy to adhere to.

Choose the Right Epoxy: Select a marine-grade epoxy that is suitable for sealing wood. Some recommended options include West System epoxy or a similar two-part epoxy resin. Make sure to read and follow the manufacturer's instructions for mixing and application.

Apply Epoxy to the Wood: Using a brush or roller, generously apply the mixed epoxy to the prepared wood surface. Pay particular attention to the areas around the drain hole, ensuring that the epoxy penetrates into the wood fibres. You may need to apply multiple coats for a thorough seal.

Allow the Epoxy to Cure: Follow the manufacturer's instructions for curing time. Epoxy typically requires several hours to cure completely, so plan your project accordingly. It's important to allow the epoxy to cure fully before proceeding to the next steps.

Sand and Prepare for Fitting: Once the epoxy has cured, lightly sand the surface to create a smooth finish. Remove any dust or debris with a tack cloth or a damp cloth. Ensure that the epoxy has sealed the wood effectively, and there are no gaps or imperfections that could allow water ingress.

Fit the New Drain Tube: Follow the manufacturer's instructions for fitting the new drain tube. Typically, this involves measuring the thickness of the transom, cutting the tube to the appropriate length, and sealing it in place with marine-grade adhesive or sealant. The specific process may vary depending on the type of drain tube you are installing.

By following these steps and allowing adequate curing time for the epoxy, you will effectively seal the wood and create a durable barrier against water intrusion. This will help ensure the longevity of your boat's transom and drain system.

Inserting the new drain tube

• Prepare the Hole: Before inserting the new drain tube, ensure that the hole is clean and dry. If there is any old sealant or residue, use a suitable tool like a screwdriver, hammer, or copper pipe cleaning brush to remove it. You may also need to widen the hole slightly to accommodate the new tube and allow room for a sealant.
• Seal the Wood Core: To protect the wood core of your boat's transom, apply a sealant or epoxy to the inside of the hole. This step is crucial to prevent water intrusion and ensure the longevity of your boat. Allow the sealant or epoxy to dry completely before proceeding to the next step.
• Prepare the New Drain Tube: Measure the thickness of the transom at the location of the drain tube. Cut the new drain tube to the appropriate length, making sure it is slightly longer (about 1/8" to 3/16" or a quarter of an inch) than the thickness of the transom. This will ensure a snug fit. Coat the outside of the tube with a suitable sealant or adhesive, such as 3M 4200, 5200, or marine epoxy.
• Insert the New Drain Tube: From the inside of the boat, insert the coated drain tube into the hole. Use clamps or a similar tool to hold the tube in place, making sure it is securely positioned.
• Create the Flange: On the protruding end of the drain tube, use a hammer and a steel bar slightly smaller than the inside of the tube to create a flange. Tap the steel bar gently with a hammer to work the end of the tube down and form a flange. Clean up any excess sealant that squeezes out.
• Seal and Secure: Apply a bead of sealant around the flange and the transom on both sides. Use stainless steel finishing pieces or flanges, and tighten them onto each end of the tube. Ensure that the flanges are snug against the inner and outer transom surfaces. Wipe away any excess sealant.
• Final Checks: Once the new drain tube is in place, allow the sealant to cure completely. Check for any leaks and ensure that the tube is securely fastened and does not move.

By following these steps, you can successfully insert a new drain tube in your boat, ensuring a watertight seal and proper drainage. Remember to work carefully and take your time to avoid damaging the boat or the new drain tube during the installation process.

Finishing off the new flange

To finish off the new flange, you will need to use a flanging tool to flare the new drain tube. You can purchase one of these tools online or from a boating supplies store. However, some people choose to make their own using a bolt, washers and a wing nut.

Before using the flanging tool, coat the tube with 3M 5200 or 4200. You can also use epoxy or marine-grade caulking. Insert the tube into the hole and use clamps to hold it in place. Then, use the flanging tool to flare the tube.

Alternatively, you can flare the tube by hammering it into shape. To do this, take a steel bar that is slightly smaller than the inside of the tube and use it, along with a hammer, to work the protruding end down to form a flange.

Finally, clean up any excess sealant that has squeezed out.

Frequently asked questions