Installing A Bimini Top: Aluminum Boat Upgrade

Bimini tops are a great way to create shade on your boat and protect yourself from the sun. They are also versatile, allowing you to fold them back to catch some rays, trailer home, or store your boat. In this article, we will be discussing how to install a Bimini top on an aluminium boat, which is a simple DIY project that can be completed in a few hours with the right tools and instructions. We will cover the tools and supplies needed, the steps to assemble the Bimini top, and the process of installing it onto your boat.

Selecting the right size

Before installing a Bimini top on your aluminium boat, it is important to select the right size. Bimini tops come in a variety of sizes, and the right one for you will depend on the portion of your boat you want to be covered and how much shade you require.

Firstly, determine what area of your boat you want the top to shade and cover. Bimini tops come in 5', 5'6", 6', 8', 9', and 10' lengths. The most common length is 6 feet. The length of the top runs from the front of the boat to the back (bow to stern) and the width is the distance between the main mounting points on either side rail (port and starboard) of the boat. The height of the top is the distance from the mounting points to the desired overhead position.

If you want to be able to stand underneath the Bimini, make sure that the height, when combined with the distance below the mounting point, offers sufficient headroom. If you only need shade while seated, you can choose a shorter top. Keep in mind that you will have less shade as you go up in height.

Once you have determined the desired length, width, and height of the top, you can select a Bimini top that matches those dimensions. Some Bimini tops are also adjustable, so you can vary the length and height to suit your needs.

Positioning the top

First, you'll need a helping hand. Ask a friend to hold the fully extended top in place while you decide where the deck hinges should be installed. It's important that the deck hinges are positioned exactly opposite and parallel to each other to prevent the top from binding when folded. If you can't mount the Bimini top on the gunwales, consider using side-mount deck hinges for vertical surfaces such as cabin bulwarks. Make sure to leave minimal interference in the cockpit when the top is stowed.

Next, you'll want to mark the mounting holes for the deck hinges. Place pieces of masking tape on the mounting surfaces and use the deck hinges to mark the holes. Before drilling, double-check that there are no hoses or wires underneath. After drilling the holes, chamfer them with a countersink bit to prevent gel coat cracking. Then, remove the masking tape and apply a marine polysulfide sealant to the surface. Screw each deck hinge into place, using nuts and bolts if possible. Wipe away any excess sealant with a clean rag.

Now, it's time to attach the Bimini top to the deck hinges. Bolt the bases of the main bow to the deck hinges and erect the top. Extend the fore and aft web straps in line with the legs of the bows to form an M-shape on each side. This will help you determine the placement of the eye straps. Mark, drill, chamfer, bed, and mount each pair of eye straps (fore and aft) with self-tapping screws. For optimal performance, mount the eye straps horizontally.

Finally, attach the snap-hooks to the eye straps and use the buckles to tighten the top evenly. Ensure that the top is secure and stable by adjusting the tension clips.

With these steps, you'll have your Bimini top positioned securely and ready to provide shade on your aluminium boat.

Mounting the deck hinges

Now that you have selected the size of your Bimini top and positioned it with the help of a friend, it's time to mount the deck hinges. This will involve marking and drilling holes, so be sure to have your power drill and bits, countersink bit, and screwdriver set ready. It is also important to have a friend help you hold the top in place as you work.

First, place pieces of masking tape on the mounting surfaces. This will protect the surfaces from cracking while drilling. Use the deck hinges to mark the mounting holes for each. Before drilling, be sure to check that there are no hoses, wires, or other obstructions underneath the mounting surfaces. After marking the holes, carefully drill each one using the recommended drill bit indicated in the instructions. If you are working with a fibreglass boat, you may want to use a countersink drill bit to prevent chipping the fiberglass.

Next, chamfer the holes with a countersink to eliminate gelcoat cracking. Remove the masking tape and bed the surface with a marine polysulfide sealant. This will help to protect the holes and ensure a secure fit for the deck hinges. Now, screw each deck hinge into place, using nuts and bolts where possible. Finally, use a rag dampened with a solvent to clean up any excess sealant.

With the deck hinges securely in place, you are now ready to install the Bimini top and eye straps.

Installing the top and eye straps

Now that the deck hinges are in place, it's time to install the top and eye straps. Start by bolting the bases of the main bow to the deck hinges. Then, with some help, erect the top and extend the fore and aft web straps in line with the legs of the bows to form an M-shape on each side. This step will help you determine where to mount the eye straps.

Once you've marked the mounting position for the eye straps, it's time to drill the holes. Use a drill bit of the appropriate size, and be sure to follow the same drilling precautions as before. Drill the holes, chamfer them with a countersink, and then bed the surface with a marine polysulfide sealant. Wipe away any excess sealant with a rag.

Now, mount the eye straps. The eye straps should be mounted horizontally and secured with self-tapping screws. Be sure to mount them at the same position on each side of the boat for symmetry and stability.

With the eye straps in place, you can now attach the snap-hooks to the eye straps. Use the buckles to tighten the top evenly, ensuring that it is level and secure.

Locating the right spot for the tie-down straps

First, you need to understand the purpose of the tie-down straps. These straps are essential for securing your Bimini top in place and ensuring it can withstand wind and other elements while you're out on the water. The straps should be angled away from the top, creating a taut but not overly tight connection.

Now, let's get to the installation process. You'll want to start by extending the straps out at approximately a 45-degree angle. This angle provides the optimal tension for securing your Bimini top. Once you've extended the straps, carefully mark the spot where each strap meets the gunwale of your boat. It's important to ensure that the straps are extended and marked at exactly the same distance from the bow or stern of the boat. This will ensure that the top is installed evenly and securely.

After marking the spots, it's time to install the "pad eyes" or attachments for the tie-down straps. These attachments are usually in the form of eye straps, and they should be installed at the marked locations, both fore and aft. Use the appropriate drill bits and screws to securely fasten the eye straps to the gunwale. Make sure to follow the same drilling precautions as you did when installing the deck hinges, being cautious of any cables or wiring underneath the gunwales.

Finally, connect the tie-down straps to the eye straps using the clips provided. Tighten each strap by sliding the tension clip to ensure that the Bimini top is level and securely held in place. This will help ensure that your Bimini top remains stable and provides adequate shade while you're out on the water.

Remember to double-check all your measurements and connections before finalising the installation. By taking your time and following these steps, you'll be able to locate the perfect spot for your tie-down straps, ensuring a safe and enjoyable boating experience under your new Bimini top.

Frequently asked questions