Installing A VHF Radio
By Lenny Rudow
Few items on your boat are as important as your VHF radio, which is your most reliable link to the outside world. But if it's not properly installed, failure is likely. Luckily, installing a new VHF is a relatively easy project that just about any boater can do on his or her own. Just follow these steps, and you'll be on the airwaves in no time.
Step 1: Securing The Binnacle Mount
Most do-it-yourselfers will binnacle-mount their radio, and that's what we'll deal with here. Flush mounts have more shape and space constraint; plus you have to cut a large hole in the helm, a job perhaps best left to the professionals. Fortunately, VHFs that come with binnacle mounts also come with a mounting template. Choose a location for your radio where you can easily operate it while running the boat, and which is shielded from the weather and direct sunlight, if possible. Secure the mounting template in place with masking tape. Check underneath the helm before drilling through it, to make sure the area is clear of wires, panels, gauges, and other items! Also check space above the template to be sure there's adequate clearance for the radio and that its location won't interfere with other gear, such as throttle movement.
Find the drill bit size that matches the radio's included mounting hardware, and drill the mounting holes in the helm as indicated by the template. After drilling the holes, remove the template and all fiberglass dust. Run a bead of silicon sealant around the holes, set the binnacle mount in place, and insert the mounting hardware. If the included hardware consists of screws, replace them with through-bolts and aircraft-grade Nylock locking nuts, which will keep the mount more secure.
Step 2: Running The Wires And Cables
Before you can get power to your new radio, you'll need to drill one more hole in the helm, this one for the wires. To determine the best location, put the radio in the binnacle mount and see where the wiring harness falls. Locate a spot for the hole that won't force any hard or abrupt bends in the wires, and be sure to use a bit that makes a hole of sufficient size for both the wiring harness and the antenna cable. After drilling the hole, feed the radio's wires down into it. You'll also need to bring the antenna cable up through the hole, but first, remove the cable's connector by cutting it off. Discard the old connector – reusing it risks a poor connection – and after feeding the cable up through the helm, attach a new Centerpin PL-259 connector to the end according to the included instructions.
The rest of the wiring work will have to be done from under the helm; depending on the situation, you may or may not need to extend the power leads for the radio to reach your power source. If you do need to extend them, use only the wire type and size(s) that conform to ABYC standards (see our Tech sidebar). Crimp butt connectors to the wire connections, protect them with the adhesive-lined heat-shrink tubing, and close off any gaps with liquid electric tape. At the terminal ends, crimp on terminal connectors, again protecting the connections with adhesive-lined heat-shrink tubing and liquid electric tape. Don't attach the terminal connectors to the power source just yet; we'll do this as we complete the final stage of this project.
Step 3: Interfacing The VHF With Your GPS To Allow DSC Functionality
You might be tempted to skip this step. Don't! According to the Coast Guard, even though all VHFs sold in the U.S. are required by law to have DSC functionality, 90 percent of the boats with GPS and VHF units onboard don't have them properly interfaced — even though DSC (which gives the Coast Guard your exact location, identity, and boat information automatically, if you make a mayday call), is one of the best and most cost-effective safety features available today.
Getting your GPS and VHF to communicate is a lot easier than most people think. The units talk via an NMEA data stream (NMEA 0183 and/or NMEA 2000) that requires just two wiring connections: an NMEA data in/out, and a ground. Unfortunately there's no standard color coding for these wires, so you'll have to refer to your owner's manuals to find out which wire is which. Once you've done so, connect the GPS data-out wires with the VHF data-in wires, by crimping on butt connectors. Once again, finish them off with adhesive-lined heat-shrink tubing and liquid electrical tape. CAUTION: Never use wire nuts in place of butt connectors for these (or any other onboard electrical) connections! Older GPS units may not have an NMEA data output; if your GPS is that old, it's time to invest in a new unit.
Step 4: Securing The System
With everything in place, it's time to batten down the hatches. Start by securing a clamshell fitting (see photo above) over the wiring hole in the helm, and seal the opening with a healthy dose of silicone to prevent water intrusion. Next, use tie wraps or cushioned clamps to support the power and NMEA interface wires at least every 18 inches, in accordance with ABYC recommendations. Finally, with the battery switch turned off, attach the power leads. Ideally this would be negative to a ground bar, and positive to a dedicated circuit breaker at a breaker panel with tripping capacity as recommended by manufacturer. Now, you're ready to turn the battery back on and test the system. Perform a standard radio check on a non-commercial and non-government ("working") channel, such as 68 or 72, to make sure everything is operating properly. Then fill the cooler with snacks and drinks and go enjoy some time off the dock. After completing this job, you
Lenny Rudow is BoatUS Magazine's electronics editor.
— Published: October/November 2011
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- Your VHF should recognize the NMEA data stream automatically, but some GPS units need you to activate an NMEA-out setting in the main menu; see your owner's manual for info on how to do so, if necessary.
- Always run your drill at full speed when it makes contact with fiberglass; a slowly turning bit is more likely to grab the gelcoat, causing it to splinter and chip.
- When starting to drill a hole, it also helps to make a small starter indent with a sharp pointed tool or very small drill bit to keep the main bit from "walking" as you begin.
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