How to Add an Aluminum Radar Arch to Your Boat?

One of the up-and-coming must-have accessories for most boaters is the “arch.” Generally built of aluminum tubing and originally designed as a radar and antenna support, it has become a common symbol of offshore fishing boats — especially walkaround and cuddy models. More recently, it is being used as a styling cue for larger runabouts and cruisers and as a wakeboard tower for the ski-boat set. The center console often employs a T-top, which serves the same purpose.

Arches are useful for more than supporting just outriggers, radar scanners and other antennas, however. In their most basic form, they also hold navigation lights, rod holders, cockpit floodlights and, on boats used routinely for wakeboarding, the mandatory stereo mega speakers. In more complex forms, they form structural supports for canvas or fiberglass sunshades, and elevated platforms (or tuna towers) for dual-control stations and sighting fish.

Along with companies such as Monster Tower (877/77-TOWER; and Taylor Towers (505/344-3586;, Barnegat, New Jersey-based Atlantic Towers (800/831-8889; builds radar arches and towers that are shipped in kit form and easily installed by do-it-yourselfers. For our installation, we chose Atlantic Tower’s simplest offering: it is Fishing Arch. With an easily adjustable width, the Fishing Arch fits various boats and comes standard with four rocket-launcher rod holders and a wide attachment point on top for a radome and plates for attaching other antennas. More elaborate towers, T-tops and arches are available, and custom designs are also offered. The cost of the basic arch is $1190.

Aluminum Radar Arch

Most installations will require relocating the boat’s white anchor/navigation light to the top of the arch to remain compliant with the U.S. Coast Guard’s 360-degree nighttime visibility requirement. The arch used for this project is constructed of 2-inch aluminum tubing, which makes it easy to route wiring from various electronic components.

In our case, we chose a hinged mounting system that allows us to tilt back the arch for easier trailering and storage. Fixed-mount arches are also available. The Atlantic Towers unit comes with all the components and fittings required to complete the installation.

Follow along while we install the Atlantic Tower on a Triton 2486 walkaround:

STEP 1: The main part of the tower (1A) is shipped in two separate parts. This allows for smaller packaging and reduces freight costs.

The smaller component parts (1B) consist of the plastic shims, mounting hardware and installation video. The kit comes complete with Loctite and Marine-Tex for the mounting pins. The aluminum plate is the center section of the arch. It slides over each end of the two halves at the top and is the point at which the arch is adjusted for width.

STEP 2: Arch width must be carefully measured to include any shims, plus a bit more. This is fully explained in the video. The purpose is to put a slight amount of tension in the arch to form a more rigid structure. The key to a successful installation is the careful measurement. Measure once and then measure again.

Width adjustments are made at the top of the arch — but width measurements are taken at the mounting point with the mounting hardware temporarily installed. Once the width has been determined, center the radar plate.

STEP 3: Drill the eight bolt holes that hold the unit together using the supplied drill guide. Then, bolt the three pieces together using the Allen head screws and cap nuts.

Carefully determine the precise mounting location before proceeding. Two people are required for this operation. The arch is quite tall and, in most cases, you will want to shorten it. Again, careful measurement is the key. The arch can be shortened by using a hacksaw or large pipe cutter to trim the lower legs. When determining the arch’s position, wrap the legends in cloth and secure with tape to prevent scratching the boat.

When determining the mounting location, be sure to consider the clearance for the shade top; for example, will the top fold with the arch in place? Check the arch’s position fore and aft. Placing the arch too far aft will make it difficult to walk forward along the gunwale of many walkaround cabin boats. Also, check for height. Will you be able to reach the rod holders once the arch is in place? These points are fully covered in the installation video.

Aluminum Radar Arch

STEP 4: In this installation, the fit between the arch and Bimini is too tight. If the top extends below the arch, leave enough space between the arch and Bimini to allow the canvas to billow in the wind without slapping against the arch.

In fact, our Triton installation is not ideal. With the arch installed low enough for the rod holders to be reached and forward enough so passage along the catwalk is convenient, the arch ends up interfering with the Bimini. The top can’t be deployed or stowed with the arch in position. We can raise and lower the top by tilting the arch back — which, admittedly, is a hassle. We plan on fixing this by either shortening the Bimini’s main- and backstay of the top, which will lower it and move it slightly forward or by putting the mainstay anchor on a slider that will allow the top to be moved forward and aft. We may have to do both.

STEP 5: The mounting hardware consists of the tube ends that are epoxied in place using the supplied Marine-Tex. Mount the rear tube hardware first. The 3/8-inch bolt passes through the mounting plate to form a hinge, allowing the arch to be lowered for trailering or canal bridges.

STEP 6: Once the arch’s location has been determined, measure and install the hinge for the rear tubes on the cockpit coaming. Again, measure carefully and don’t assume that the boat’s coaming is identical on each side. Check fore and aft dimensions, as well as vertical height. This will determine the spacing between the forward mounts and the coaming, which you will want to be as equal as possible. A small error here will make a large difference in the spacing of the front mount.

STEP 7: Mount the rear bracket or hinge — in this case, first using the supplied bolts, plastic fairing block (if needed) and the plate. In our installation, access to the inside of the coaming became available by removing the molded storage compartments. Be sure to install the backing plates behind the tower mounts. If access is not available behind the panel, it may be necessary to cut an access hole and install an inspection plate.

STEP 8: With the rear bracket and mounting hardware installed, the tower tubes can be inserted and the location of the forward mounts determined. The vertical location of the forward mounts affects the angle of the arch. In general, the arch looks best when the plate for the radar antenna is parallel with the boat’s keel. If you are installing a radar antenna, you may also consider angling the arch a few degrees forward to keep the antenna level when the boat is on a plane with the bow slightly raised.

STEP 9: On our installation, the forward brackets required the use of a plastic shim that had to be faired to keep the brackets vertical. The plastic can be trimmed with a plane or sharp knife. We used a belt sander. Proper alignment of this bracket is necessary to allow the tube ends to mesh easily in the bracket. Be sure the holes line up so that the quick-release pins can be easily inserted and removed. The arch can flex, but not by much, and nothing should bind.

STEP 10: Countersink the tube, drill and tap a 1/4-20 hole and secure with 1/4-20 by 5/8 screws. The screws should be installed with the Loctite provided.

The completed installation is as handsome and professional looking as any factory-installed unit. We now have a tall base for mounting antennas, cockpit lighting, and navigation lights — not to mention outriggers so we can get more baits in the water.

Tool Time

Aluminum Radar Arch

The tools required for this job include a tape measure, Phillips screwdriver, Allen wrench, open-end wrenches, hacksaw or large pipe cutter, a file to smooth rough cuts, a drill and 1/4-20 tap and countersink. There are a few tools here that the average do-it-yourselfer might not have, but they are neither expensive nor hard to find. For example, if the plastic shims have to be faired to match the contour of the side of the boat, a belt sander or small plane will be needed.

The kit for this project’s Atlantic Towers arch comes with an installation video that should be watched before starting, as it provides helpful hints and installation procedures.

Timewise, our installation took two men approximately one full day. By the way, you use a 6000K h11 led bulb for illuminating when you add an aluminum radar arch to your boat.

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