Bolting Boat Seats: The Aluminum Edition

There are several ways to bolt seats onto an aluminium boat. One way is to use stainless bolts/nuts and go all the way through the mounting surface if possible. It is also recommended to use stainless reinforcing plates on both the top and bottom of the mounting surface for added support. If you are unable to get stainless plates, a good hardwood will do. Another method is to bolt wood down across the length of the bench and then attach the seats to that. It is important to note that you should not use treated lumber as the copper in it will eat through the aluminium. Instead, use normal lumber and treat it with a sealant or a coating of fibreglass resin.

Using plywood to reinforce the aluminium boat seat

When bolting seats onto an aluminium boat, it is important to reinforce the structure to reduce flex and prevent bolts from being ripped out of the aluminium. One way to do this is by using plywood.

If you are planning to use plywood to reinforce the aluminium boat seat, it is important to select the appropriate type of plywood and fastening method. Firstly, it is recommended to avoid using treated lumber, as the copper in treated wood can cause corrosion in aluminium. Instead, opt for regular lumber, marine-grade plywood, or AC exterior plywood.

If you choose regular lumber, be sure to treat it with a sealant like Johnson's Water Seal or a coating of fibreglass resin before installation. For a more durable option, marine-grade plywood is recommended, especially if the plywood will be exposed or you want to ensure a longer-lasting boat seat. Sealant or paint can be applied to marine-grade plywood to further enhance its durability and aesthetics.

When fastening the plywood to the aluminium boat, several methods can be considered. One option is to use blind rivets, which provide a rock-solid installation and allow for easy removal if needed. Another option is to use stainless steel bolts with washers and reinforcing plates. Ensure that the bolts are long enough to go through the mounting surface and consider using a thicker piece of aluminium or hardwood as backing for added support.

Additionally, consider the thickness of the plywood. For adequate support, a minimum thickness of 5/8" is recommended for the application.

By following these guidelines and selecting the appropriate materials and fastening methods, you can effectively use plywood to reinforce the aluminium boat seat, ensuring a sturdy and durable installation.

Drilling holes for bolts

Planning the Drill Holes:

Before you start drilling, it's important to plan the placement of the holes carefully. Measure the dimensions of the seat and the mounting surface on your aluminium boat. Mark the positions where you want to drill the holes, ensuring they align with the bolt holes on the seat base. Use a ruler or a straight edge to ensure the holes are evenly spaced and level.

Choosing the Right Drill Bit:

Select a drill bit that corresponds to the size of your bolts. The drill bit should create holes slightly larger than the bolt diameter to allow for easy insertion and some room for manoeuvrability during the installation process. It's a good idea to test the drill bit on a scrap piece of material first to ensure you have the right size.

Drilling Technique:

Clamp the aluminium boat surface securely or ask an assistant to hold it firmly in place. Start drilling slowly and with moderate pressure to create a pilot hole. Once the drill bit has established a path, you can increase the speed and apply more pressure to complete the hole. Use a steady hand and maintain consistent pressure to ensure a clean cut and prevent the aluminium from warping or bending.

Preventing Stripping:

Aluminium is a relatively soft metal, so it's important to take precautions to avoid stripping the threads of the holes. Use a sharp drill bit appropriate for metal drilling, and consider lubricating the bit with cutting oil or a similar lubricant to reduce friction and heat buildup. Drill slowly and carefully, and avoid forcing the bit through the metal.

Backing Plates and Reinforcement:

To reinforce the mounting surface, consider using backing plates or thicker pieces of aluminium. Drill through both the mounting surface and the backing plate together, ensuring the holes align. Stainless steel reinforcing plates or hardwood plates can be used if stainless steel plates are unavailable. This will provide additional support and help distribute the weight of the seat more evenly.

Finalising the Installation:

Once the holes are drilled, insert the bolts and secure them with washers and nuts. Use stainless steel bolts, nuts, and washers to prevent corrosion. Ensure all hardware is tightened securely, but be careful not to over-tighten, as this can strip the threads or damage the aluminium. Test the stability of the seat by applying moderate pressure and ensuring it holds firmly in place.

Remember to follow safety precautions when operating power tools, and always wear appropriate protective gear, including eye protection and gloves.

Using stainless steel bolts and nuts

When bolting seats onto an aluminium boat, it is recommended to use stainless steel bolts and nuts. Stainless steel is the standard in all marine applications and is highly resistant to corrosion.

To install seats onto an aluminium boat using stainless steel bolts and nuts, follow these steps:

First, reinforce the floor of the boat. One way to do this is by bolting a piece of wood across the length of the bench and then attaching the seats to the wood. This will reduce flex and lessen the chance of ripping the bolts out of the aluminium. It is important to note that you should not use treated lumber as the copper in it will eat through the aluminium. Instead, use normal lumber and treat it with a sealant or a coating of fibreglass resin.

Next, you will need to decide on the type of bolts and nuts to use. Hex head bolts can be used to tightly secure two pieces together. Allen head bolts work similarly but are designed to fit flush with the surface. Carriage bolts have a low profile that allows them to lock into place, and they require a nut to secure them. For wrapping objects and securing them to other objects, U-bolts can be used. Eye bolts, which have a loop at the end, are perfect for running rope through. Hanger bolts can be installed in wood to provide a stud to secure hardware with nuts and washers.

Nylock nuts are thicker nuts with a ring to prevent them from coming loose. Castle nuts have slots on one side to provide space for wire or cotter pins to lock them in place. Tee nuts are ideal when using a washer and nut is not possible, and they can also be used for flush applications. Wing nuts can be hand-tightened using the two tabs at the top, but they may not be suitable for marine applications as they can become loose more easily.

When bolting seats, it is also important to consider the use of washers. Flat washers are general-use washers that can be used when loads do not need to take up large spaces. Fender washers have double the surface area of flat washers and can spread loads over a larger area. Lock washers prevent bolts and nuts from coming loose due to vibrations.

Finally, when bolting seats onto an aluminium boat, it is important to ensure proper fitment and tightness of the bolts and nuts. This will help to ensure the safety and security of the seats.

Adding a swivel base for easy pivoting

Adding a swivel base to your aluminium boat's seats will make pivoting a breeze. There are a few ways to go about this, depending on your boat's setup and how permanent you want the installation to be. Here's a step-by-step guide:

Step 1: Assess Your Setup

First, check if your aluminium bench seat is filled with flotation material. This will impact your installation options. If you have access to the underside of the seat, you can use stainless bolts and nuts to secure the swivel base. If not, don't worry; there are other methods to achieve a solid installation.

Step 2: Choose Your Installation Method

Option 1: Rivets or Toggle Bolts

If you don't want to deal with bolts and nuts, consider using rivets or toggle bolts for a secure installation. Toggle bolts, such as Toggler Snaptoggles, are designed to bear weight and prevent tear-out, making them ideal for this application.

Option 2: Backing Plate

Another option is to create a backing plate for your swivel base. Cut a piece of hardwood or aluminium to fit the bench, then use angle brackets to secure it from the side lip of the bench. You can then attach the swivel base to this backing plate using stainless steel carriage bolts. This method provides a sturdy base and also allows you to mount a fish finder in front of your seat.

Option 3: Access Hole

If you're open to making a more permanent modification, you can cut an access hole in the side of the aluminium bench, directly under the seat. This will give you the space needed to install angle stiffeners over the bolts and secure them with nuts and washers. You can even use this access hole to create a recessed tackle box holder for convenient storage!

Option 4: External Brackets or Clamps

If you don't want to drill holes in your bench, you can use external brackets or clamps to mount your swivel seat. These can be purchased from marine supply stores or online.

Step 3: Finalize the Installation

Once you've chosen your installation method, it's time to bolt down the swivel base. Make sure to use stainless steel bolts and washers to prevent corrosion. If you're drilling new holes, ensure they're the right size for your bolts and consider using fender washers for added strength.

Step 4: Test and Enjoy

With the swivel base securely installed, it's now safe to attach your seat. Test the setup by gently applying weight and trying out the swivel function. Enjoy your new pivoting seat!

Using interlocking aluminium extrusions

Aluminium extrusions are widely used in the naval sector to build boats, making them lighter, faster, and more resistant. When it comes to bolting seats onto an aluminium boat, interlocking aluminium extrusions can be a great option. Here's a step-by-step guide on how to use interlocking aluminium extrusions to securely install seats in your aluminium boat:

Step 1: Choose the Right Aluminium Extrusion Type

When selecting the aluminium extrusion type, consider the size, shape, and dimensional tolerances that best fit your boat's design. You can choose from standard profiles or special profiles, depending on your specific requirements. Standard profiles are typically made with aluminium alloys like 1050, 1070, 3103, or 6060 and offer simple shapes and sizes. On the other hand, special profiles are designed with specific dimensions and shapes, usually manufactured with the 6060 aluminium alloy, which provides unique qualities.

Step 2: Prepare the Aluminium Extrusions

Before starting the installation process, ensure that the aluminium extrusions are properly treated and finished. This can include processes such as drilling and micro-drilling, bending, and calendering. These treatments will enhance the functionality and aesthetics of the extrusions. Additionally, consider anodizing the aluminium to further improve its corrosion resistance and shock absorption properties, resulting in a more durable boat.

Step 3: Understand the Concept of Interlocking Joints

Interlocking joints are a type of geometry-based joint that does not rely on fasteners or bonding for assembly. These joints are made by rotating two components into position, creating a sturdy connection. The compact mirror image design of the interlocking aluminium extrusions ensures a precise fit, and the pre-drilled countersunk holes make fixing them in place simpler.

Step 4: Assemble the Interlocking Joints

To assemble the interlocking aluminium extrusions, rotate the components into position until they interlock securely. You can add additional elements, such as fasteners or bonding agents, to further reinforce the joint and prevent accidental disassembly. This extra step will ensure that the seats are firmly attached to the boat's structure.

Step 5: Install the Seats

Once the interlocking aluminium extrusions are securely in place, you can proceed to install the seats. Ensure that the seats are properly aligned and fastened to the extrusions. Follow the manufacturer's instructions for the seat installation process, as it may vary depending on the seat model and design.

Step 6: Test and Inspect

After installing the seats, conduct a thorough inspection and testing process. Check that the seats are firmly attached and that all fasteners are tight and secure. Test the stability of the seats by applying weight and simulating typical usage conditions. Ensure that the seats do not wobble or shift and that they can withstand the expected load-bearing requirements.

Frequently asked questions