Mounting A Seat Base: Aluminum Boat Essentials

Mounting a seat base in an aluminium boat is a task that requires careful consideration of materials and methods to ensure a secure and long-lasting installation. The process involves several steps, from selecting the appropriate fasteners to reinforcing the mounting area for added stability. The type of seat base, the weight it needs to support, and the specific characteristics of the boat will all influence the chosen approach.

Using rivnuts

To use rivnuts, you will need to purchase a rivnut tool and the rivnuts themselves. These can be found at most hardware stores or online. Before you begin, make sure you have a clear understanding of where you want your seat to be located and how many rivnuts you will need.

Once you have your tools and materials, follow these steps:

• Drill holes in the aluminium boat where you want to place the rivnuts. The size of the drill bit will depend on the size of the rivnuts you are using, so be sure to check the instructions that came with your rivnuts.
• Insert the rivnut into the nosepiece of the rivnut tool. The nosepiece should be the correct size for your rivnuts.
• Place the rivnut into the hole you drilled, with the threaded side facing up.
• Pull the trigger on the rivnut tool to activate the mandrel, which will expand the rivnut inside the hole. You may need to tighten it with a wrench for extra security.
• Repeat this process for each rivnut you need to install.
• Once all the rivnuts are in place, you can bolt your seat base directly to the floor of the boat.

It is important to note that rivnuts may not be the best option if you are a larger person or expect to put a lot of weight on the seat, as they may not be able to handle the load. In this case, you may want to consider using a thicker substructure or a plate to reinforce the mounting area.

Welding and bolting

Welding

When welding, it is important to have a skilled welder who is experienced in working with aluminium. The process typically involves:

• Fabricating a bracket to reinforce the mounting area. This can be done by welding a thicker piece of aluminium, such as a 1/4" plate or a 1" x 1" aluminium square stock, to the existing structure.
• Bolting the seat base to the welded bracket using stainless steel bolts and lock nuts. This ensures a strong and secure connection.

Bolting

If you don't have access to the underside of the mounting area, you can create an access point by cutting a hole and patching it up afterwards or installing an access panel. This will allow you to bolt the seat base securely:

• Use stainless steel bolts and reinforcing plates on both the top and bottom of the mounting surface for added strength.
• Consider using toggle bolts, which are designed for drywall anchoring but can also be effective for boat seat mounting.
• Alternatively, you can use rivnuts, which are installed like rivets and provide a secure bolt connection for your seat base.

Toggle bolts

To use toggle bolts, you will need to drill holes in the aluminium boat's surface that are large enough for the bolts to fit through. The size of the holes will depend on the specific toggle bolts you are using, so be sure to check the manufacturer's instructions. Once the holes are drilled, you can insert the toggle bolts and tighten them securely.

It is important to note that toggle bolts may not provide sufficient support for a seat base on their own. It is recommended to use a thicker piece of aluminium or a backing plate in conjunction with the toggle bolts to ensure a solid installation. This can be done by drilling a hole in the centre of the pedestal outline and positioning the backing plate or thicker aluminium underneath, adding a few small flat-head screws to keep them in place.

Additionally, you can use anti-seize compound on stainless-steel fasteners to prevent the aluminium from seizing up on the bolts, making them difficult to remove in the future.

Jack nuts

When installing a seat base in an aluminium boat, jack nuts can be used to fasten the seat to the boat without needing access to the backside of the boat. Jack nuts are beneficial in this application because they won't distort the aluminium boat material and can accommodate slightly oversized holes. Additionally, they are easy to install and remove.

To install jack nuts, you will need a specialised jack nut installation tool. The tool works by threading a bolt to a jack nut, dropping the fastener into the slot of the tool, inserting it into the pre-drilled hole, and squeezing until set. Pressing the release lever and tightening completes the installation.

Backing plates

When mounting a seat base in an aluminium boat, backing plates are an important consideration for reinforcing the mounting area. Here are some detailed instructions and suggestions for using backing plates:

• Backing Plate Materials: Backing plates can be made of stainless steel, aluminium, or wood. If you choose wood, ensure it is untreated to prevent the copper in treated lumber from eating through the aluminium. Seal the wood with a suitable product, such as Johnson's water seal or fibreglass resin.
• Backing Plate Size: Determine the size of the seat and base you will be installing, and then calculate the size of the backing plates needed for good support. The plates should be large enough to span multiple ribs or the length of the bench to distribute the weight load and reduce the chance of bolts ripping out of the aluminium.
• Access for Installation: If you have access to the underside of the mounting area, you can use stainless steel through-bolts, fender washers, or backing plates. If you don't have access to the underside, consider installing an inspection port or access hatch large enough to pass the backing plates through.
• Fastening the Backing Plates: Use stainless steel bolts and nuts to fasten the backing plates to both the top and bottom of the mounting surface. Ensure the bolts are long enough to go all the way through the mounting surface and backing plates.
• Using Cutting Boards: As an alternative, you can fashion backing plates from cutting boards. Use stainless steel hardware to mount them, and you may be able to utilise the space underneath for additional storage.
• Square-to-Round Mounting Plates: If you want to avoid drilling more holes in your boat's floor, you can use a square-to-round boat seat mount plate. This type of plate converts a square bolt hole pattern into a round base pattern, providing a secure mounting option.

Frequently asked questions