Attaching A Board To Your Aluminum Boat: Easy Steps

There are several ways to attach a board to an aluminium boat. The most common methods include using bolts, screws, or rivets. For bolts, you will need access to both sides of the attachment point, while screws can be self-tapping and cut threads into a drilled hole. Rivets are another option, which can be installed with a riveting tool and create a strong hold. When choosing a fastener, it is important to consider the load it will need to bear and select an appropriate type of metal that will not corrode the boat, such as stainless steel or bronze.

Using bolts, screws, and washers

When attaching a board to an aluminium boat using bolts, screws, and washers, it is important to select the right type and size of fasteners and to consider the load they will need to bear. Here is a step-by-step guide:

Step 1: Choose the Right Fasteners

Select stainless steel bolts, screws, and washers of an appropriate grade for your application. For cosmetic applications or those involving contact with saltwater, choose 316 stainless steel to prevent rust stains and corrosion. If the fasteners will not be exposed to saltwater, 304 stainless steel can be used, but it may show some cosmetic corrosion over time.

Step 2: Prepare the Surfaces

Before beginning, clean and prepare the surfaces of the board and the boat where the fasteners will make contact. This will help ensure a secure and durable connection.

Step 3: Use Washers for Reinforcement

When attaching the board to the aluminium boat, use washers to reinforce the connection and distribute the load. Place washers on both sides of the boat where the bolt or screw passes through, as this will help to prevent the fastener from pulling through the material.

Step 4: Apply Sealant or Grease

To prevent galvanic corrosion between the stainless steel fasteners and the aluminium boat, apply a layer of sealant or grease to the threads of the bolts or screws before inserting them. You can also use products like Tef-Gel or 3M 5200, which act as a barrier and help to separate the metals.

Step 5: Insert and Tighten Fasteners

Drill pilot holes if necessary, especially when working with harder aluminium alloys. Then, insert the bolts or screws through the board and into the aluminium boat, adding washers on both sides as you go. Tighten the fasteners securely, but be careful not to overtighten, as this can strip the threads or break the fastener.

Step 6: Consider Locking Mechanisms

To prevent the fasteners from loosening over time, consider using locking mechanisms such as locknuts or thread-locking adhesives. Locknuts like nylock nuts have a nylon collar that grips the bolt to secure it in place. Alternatively, you can apply a liquid thread-locking adhesive, such as Loctite, to the clean threads during assembly.

By following these steps and choosing the appropriate fasteners, you can securely attach a board to an aluminium boat using bolts, screws, and washers, ensuring a strong and durable connection.

Drilling and screwing

Before drilling, it is important to select the appropriate drill bit for the job. For drilling into aluminium, a special bit may be required.

When drilling and screwing, the load that will be placed on the fastener must be considered. Metal fasteners are strong and offer longevity, and most can be disassembled without causing damage. The type of fastener to use will depend on the type of load. For example, bolts are suitable for sideways (shear) forces, while tensile forces (which try to stretch the fastener or pull it out of the hole) are better handled by threads or formed heads.

When choosing a metal fastener, there are several options to consider:

• Bolts: Require nuts and access to both sides of the fastening hole.
• Machine screws: Identical to bolts but thread into a tapped hole.
• Sheet-metal and wood screws: Self-tapping, they cut threads into the surface of a drilled hole.
• Rivets: These have no threads and come with a factory head on one end. The other end is deformed during installation to create a second head. Blind rivets, also known as pop rivets, are a common choice for boat owners as they can be installed with access to only one side of the fastener hole.

When using bolts or machine screws, it is important to use a strong backing plate made of aluminium or stainless steel, or heavy-duty washers to spread the load.

For attaching hardware of lesser importance or subject to little stress, screws can be used. This includes items like deck fills, ventilators, rod holders, and flagpole sockets.

When installing wood or sheet-metal screws, pilot holes are required. It is important to use the correct drill size to avoid the screw binding or breaking. For sheet-metal screws into fibreglass, the pilot hole must be slightly oversized rather than undersized to prevent binding. Chamfering the pilot holes with a countersink bit will help prevent fractures in the gel coat layer.

Lubricants can be used when installing screws to make the process easier. However, this can also make it more likely for the fastener to loosen over time. To prevent this, a liquid thread-locking adhesive can be used.

Using rivets

To attach a board to an aluminium boat using rivets, you will need to follow these general steps:

• Prepare the board and the boat surface: Ensure that the board you are using is cut to the correct size and shape, and that the aluminium boat surface is clean and dry.
• Drill holes: Using a drill, create holes in the board and the aluminium boat surface that align with each other. The holes should be slightly smaller than the rivets you will be using.
• Insert the rivets: Place the rivets through the holes in the board and the boat. Make sure the rivets are the appropriate size and length for your application.
• Secure the rivets: Use an air riveter or a hand riveter to secure the rivets in place. Ensure that the rivets are tight and form a very tight fit to maintain a watertight seal.
• Check for leaks: Once all the rivets are in place, check the boat for any leaks by filling it with water and inspecting for any signs of water ingress.

It is important to note that there are different types of rivets available, such as closed-end rivets, which are commonly used in aluminium boat construction and repair. Closed-end rivets form a sealed closure head, preventing moisture from penetrating the joints and reducing the risk of water leakage. Additionally, the use of large-headed, large-diameter rivets is recommended for a stronger and more secure connection.

Using glue

Gluing a board to an aluminium boat is possible, but it is important to note that certain types of glue will not work on polyethylene or HDPE. Some sources suggest that polyethylene cannot be glued at all. One source notes that they asked at a plastic store and were told that there is no glue that would attach polyethylene to an aluminium boat. However, some glues that are mentioned as successful include:

• Marine sealant
• 5200
• West G/flex epoxy
• Marinetex
• Contact cement
• 3M adhesive glue spray
• 3M 5200
• West Systems G-Flex
• Chemset 6105 and 6110
• Loctite Plastics Bonding System
• Epoxy with filler
• Flex Set

Before gluing, it is important to clean the aluminium with acetone or alcohol. Some sources also suggest roughing up the aluminium with a Scotchbrite pad or sandpaper, or using a flame treatment.

In addition to gluing, it is recommended to use mechanical fasteners as well. This can include drilling and threading holes in the board and filling them with epoxy, or gluing and screwing the board in place.

Using corrosion-resistant bolts

When attaching a board to an aluminium boat, it is important to consider the potential for galvanic corrosion, especially if the boat will be used in saltwater. Galvanic corrosion occurs when two dissimilar metals are connected by an electrolyte, allowing the movement of electrical current and resulting in one metal corroding more quickly than the other. In the case of an aluminium boat, using stainless steel bolts can lead to galvanic corrosion, with the aluminium acting as the anode and corroding more quickly.

To prevent this, it is recommended to use corrosion-resistant bolts made from 316 stainless steel. 316 stainless steel is a non-magnetic austenitic chromium-nickel stainless steel that also contains up to 3% molybdenum, which helps to limit corrosion in saltwater environments. When using 316 stainless steel bolts, it is important to follow these best practices to further reduce the risk of corrosion:

• Use washers: Nylon or plastic washers can be placed between the bolt and the aluminium surface to minimise the contact area between the two metals, reducing the risk of corrosion.
• Apply sealant: Coating the bolts or the contact area with a sealant, such as Tef-Gel, can also help to isolate the metals and prevent galvanic corrosion.
• Grease: Applying grease to the bolts can also minimise contact and provide protection from corrosion.
• Avoid zinc-coated hardware: Zinc-coated hardware should be avoided, as it will not hold up in saltwater environments.
• Avoid aluminium bolts: While aluminium bolts will not cause galvanic corrosion, they are simply not strong enough for most applications.

By following these guidelines and using corrosion-resistant bolts, you can confidently attach a board to your aluminium boat while minimising the risk of galvanic corrosion.

Frequently asked questions