Adding Drain Plug To Aluminum Boat: A Step-By-Step Guide

Adding a drain plug to an aluminium boat is a common procedure, with many boat owners choosing to install one to drain water that has collected in the boat. The process involves drilling a hole in the boat's transom or hull, and then installing a drain plug fitting. The type of drain plug varies, with some people opting for brass or aluminium, while others prefer plastic or nylon. It is important to use the correct sealant to prevent leaks, and some people also choose to weld the drain plug in place for added security.

Choosing the right drain plug

Size

Firstly, you need to ensure that the plug is the right size for the hole in your boat. A plug that is too small will not create a tight seal, allowing water to leak into the boat. Conversely, a plug that is too large may not fit into the hole at all. Therefore, it is crucial to measure the hole accurately and select a plug with the corresponding dimensions.

Material

The material of the drain plug is another important consideration. Common materials used for boat drain plugs include plastic, metal, and rubber.

• Plastic plugs are typically the most affordable option, but they are less durable than metal or rubber plugs. They may not be suitable for long-term use, especially if you frequently use your boat in waters with a lot of debris that could damage the plastic.
• Metal plugs, such as those made from stainless steel, brass, or aluminium, offer more durability. However, they can be prone to rust over time, especially if exposed to saltwater. To mitigate this, some metal plugs are treated with corrosion-resistant coatings, such as anodization or galvanization.
• Rubber plugs are generally the most durable option and are well-suited to aluminium boats. They create a tight seal and are highly resistant to corrosion. However, they tend to be more expensive than plastic or metal plugs.

Type

There are several types of drain plugs available, each with its own advantages and disadvantages:

• Screw-in plugs: These are screwed into the hole, providing a secure seal. They are easy to install and remove but may be difficult to turn if the hole is not perfectly aligned.
• Push-in plugs: As the name suggests, these plugs are pushed into the hole and provide a tight seal. They are simple to install and remove but can be challenging to remove if they become stuck.
• Lever-operated plugs: This type of plug is inserted into the hole and held in place by a lever. They are convenient to install and remove, but a stuck lever can make them difficult to operate.
• Twist-lock plugs: Twist-lock plugs are inserted into the hole and locked in place with a twisting mechanism. They offer ease of installation and removal but may be tricky to operate if the mechanism becomes stuck.

Location

When choosing a drain plug, consider its location on the boat. Some plugs are located in the transom, while others are in the bilge. Selecting a drain plug located in an easily accessible area is beneficial, as it will simplify installation, removal, and maintenance.

Compatibility

It is crucial to select a drain plug that is compatible with your boat's material. As mentioned earlier, using a plug made from a different metal can lead to galvanic corrosion, damaging your boat. If your boat is made from aluminium, it is generally best to choose a drain plug made from the same material or opt for a non-metallic option like rubber or plastic.

In summary, choosing the right drain plug for your aluminium boat involves considering the size, material, type, location, and compatibility of the plug. By taking these factors into account, you can ensure that your boat remains safe and seaworthy for years to come.

Drilling a hole for the drain plug

Drilling a hole in your aluminium boat to install a drain plug is a simple process, but it requires careful attention to detail. Here is a step-by-step guide to help you get started:

Step 1: Choose the Right Drain Plug

Before you start drilling, it is crucial to select the correct drain plug for your boat. Drain plugs come in various types, including screw-in, push-in, lever-operated, and twist-lock plugs. Choose a plug that fits snugly into the hole and consider the material, such as plastic, metal, or rubber, keeping in mind durability and cost.

Step 2: Identify the Drilling Location

Locate the area where you want to install the drain plug. Common locations include the transom or the bilge. Choose an area that is easily accessible for installation, removal, and maintenance. Mark the exact spot where you will drill the hole, ensuring it is clear of any obstructions.

Step 3: Gather the Right Tools

Make sure you have the necessary tools and equipment for drilling. This includes a drill with the appropriate drill bits for aluminium, a spade bit for the hole, and a silicone sealant to create a watertight seal around the edges of the hole.

Step 4: Drill the Hole

Once you have marked the drilling spot and gathered your tools, it's time to drill. Carefully drill the hole at the marked location, following standard safety precautions for drilling into aluminium. Ensure the hole is the correct size for your chosen drain plug, as specified by the manufacturer.

Step 5: Prepare the Hole

After drilling, clean the area around the hole to remove any debris or shavings. Apply a bead of silicone sealant around the edges of the hole to create a watertight seal. This will help prevent leaks and water intrusion.

Step 6: Install the Drain Plug

Finally, it's time to install your chosen drain plug. Insert the plug into the hole and tighten it by turning it clockwise. Make sure to follow the manufacturer's instructions for proper orientation and installation of the plug. Test the plug to ensure it is secure and creates a tight seal.

Remember to regularly inspect your drain plug for any signs of wear and tear and replace it if necessary. By following these steps, you can successfully drill a hole and install a drain plug in your aluminium boat, ensuring proper drainage and preventing water accumulation.

Using sealant to prevent leaks

To prevent leaks in your aluminium boat, it is important to use a sealant that provides excellent watertightness and added protection. Polyurethane-based sealants are often recommended for boats as they can adhere to many materials and their watertightness is recognised in the transport industry.

When choosing a sealant, look for one that provides good flexibility and offers resistance to UV rays and chemicals. It should also not be too adhesive, so it can be easily removed if necessary.

One recommended sealant for aluminium boats is Marine GOOP, which has proven to be both tougher and more elastic than other sealants. It also has superior adhesion to bare aluminium and can seep into fine seams and rivet holes. Another option is 5200 Marine Fast Cure, which is commonly used in the industry and has a good reputation.

To ensure a robust and complete leak-stopping system, it is important to over-coat your rivets, seams, and seals with a good, high-quality boat coating. Wetlander boat coatings, for example, have excellent adhesion to both aluminium and sealant. Coating Wetlander over your seals and the hull bottom will create a double-protected waterproof seal.

Another option for repairing leaks in aluminium boats is to use an epoxy leak sealer. TotalBoat Aluminum Boat Leak Sealer is a 2-part epoxy sealer that comes in a convenient cartridge with a mixing tip. It can be used to repair leaking rivets, cracks, and seams, and can be applied in temperatures as low as 40°F. It is important to properly prepare the aluminium surface before application by cleaning, drying, and sanding the area.

Avoiding incompatible materials

Aluminum is a great material for boats due to its light weight, strength, and corrosion resistance. However, when adding a drain plug to an aluminum boat, it's important to consider the potential for corrosion caused by incompatible materials. Here are some tips to avoid this issue:

Use Compatible Metals:

When choosing a drain plug and installation method, opt for metals that are compatible with aluminum. Some compatible metals include specific alloys of aluminum itself, such as 5052, 5083, 5086, and 6061. These alloys are commonly used in the marine industry and offer good corrosion resistance. Avoid using metals that are very different from aluminum in the galvanic series, as this can lead to galvanic corrosion.

Avoid Galvanic Corrosion:

Galvanic corrosion occurs when two dissimilar metals, such as steel and bronze, are in contact with each other and exposed to seawater or even just saltwater spray. This creates an electrical current that causes the less noble metal to corrode while protecting the more noble one. To prevent this, use compatible metals and ensure that different metals don't come into direct contact with each other. You can also use sacrificial anodes, which attract corrosion and protect other metals.

Be Wary of Stainless Steel:

While stainless steel is often considered a durable material, it is not always the best choice for underwater applications. Some grades of stainless steel, such as 316L, are susceptible to crevice corrosion or oxygen-depletion attack. This type of corrosion can occur in hidden areas, such as under cutless bearings, and weaken the metal over time. If you must use stainless steel, opt for grades that are resistant to oxygen-depletion attack.

Consider Alternatives:

In some cases, you may want to consider alternative materials for your drain plug. For example, nylon plugs are often used in aluminum boats and offer good compatibility. Rubber bung-type plugs are another option that can provide a tight seal and prevent water ingress. Just be sure to choose a plug that fits your boat's drainage system securely.

Monitor and Maintain:

Even with compatible materials, it's important to regularly monitor and maintain your drain plug and the surrounding area. Check for any signs of corrosion, especially if your boat is frequently exposed to saltwater. Keep the area clean and free of debris, and consider using corrosion-resistant grease on threads to prevent seizing and make removal easier.

By following these guidelines and choosing compatible materials, you can effectively avoid issues with incompatible materials when adding a drain plug to your aluminum boat. Remember to research the specific metals and alloys involved and always prioritize corrosion resistance and compatibility to ensure the longevity of your boat.

Finding the correct tools

To add a drain plug to an aluminium boat, you will need a few tools and materials. Here is a list of the items you will need to gather before starting the project:

• Drill: You will need a drill to make holes in the aluminium boat for installing the drain plug. Choose a drill that is suitable for drilling through metal and has adjustable speed settings.
• Drill Bits: Make sure you have the appropriate-sized drill bits for making holes in the boat. The size of the drill bit will depend on the diameter of the drain plug and tubing you choose.
• Spade Bit: If you plan on using aluminium tubing, you will need a spade bit to create a hole in the transom of your boat.
• Wrench or Socket Set: You will need a wrench or socket set to tighten the drain plug and any fittings or fasteners.
• Screwdriver: A standard or Phillips-head screwdriver may be needed for securing fasteners or adjusting the drain plug.
• Sealant: A waterproof sealant such as silicone caulk or marine-grade adhesive will be necessary to create a watertight seal around the drain plug.
• Flaring Tool: If you are using a flaring tool kit to install the drain plug, make sure you have the correct size and type of flaring tool for the tubing you choose.
• Grease: A light coating of grease on the flaring tool and tubing can help the process and protect the metal.
• Safety Gear: Don't forget to wear safety gear, such as gloves and eye protection, when working with tools and drilling.

Once you have gathered these tools and materials, you can begin the process of installing the drain plug on your aluminium boat. Remember to take your time, work carefully, and refer to specific instructions provided by the manufacturer of your chosen drain plug and tubing.

Frequently asked questions