How To: Add Digital Switching to Your Boat

Going digital is easy. Mike Smith, a self professed Luddite, shares some tech tips.

Switches are simple machines, but digital technology can make them better.

In 1811, a gang of disgruntled English textile workers destroyed mechanized looms and other weaving apparatus in Nottingham. Called Luddites, after Ned Ludd, a weaver’s apprentice who had supposedly done the same thing 22 years earlier, the group was against new industrial technology replacing skilled workers. I understand how they felt, but not because of economics; I think today’s technology often takes away from the joy of doing things using learned skills. However, it sure comes in handy sometimes: Who wants to navigate through fog without a radar, GPS and chartplotter? Been there, done that, and now my nerves are too old for so much excitement. But there’s still some Ned Ludd in me, as I discovered during a recent conference with other Power & Motoryacht folks.

One of our editors said he thought digital switching systems, showing up on many new boats, would make a good topic for this column: While the ultra-sophisticated systems designed for OEM installation are complex to spec, install and program, Garmin, Maretron, CZone and others, build simpler aftermarket systems for skippers who want a taste of the latest and greatest, but don’t need NASA-level complexity. I thought, “Why does everything in life have to be digital? And why do so many folks feel that flipping a mechanical switch is such an onerous task?” I didn’t see what the big deal about digital switching is—but then I have toggle boat switches older than most of the editorial staff. The image of Ned Ludd smashing a loom popped into my head, but in an effort not to be a last-century curmudgeon I agreed to look into it.

Wiring in most boats is a multicolored spaghetti of conductors snaking their way from the main breaker panel through switches at the helm (and maybe two helms) and into the cabins, etc., to whatever appliances they control—and then there’s another wire snaking back to the ground bus. Digital switching makes initial DC wiring less complicated. It does this by linking a digital switch system, mounted someplace convenient, to one or more multifunction displays, or, in some systems, to weather-sealed touchpads, using a single NMEA 2000 (N2K) cable attached via the vessel’s N2K backbone. The multi-function display (MFD) becomes the switch panel and mechanical breakers and switches suddenly become a thing of the past. Once the system is set up, operation is straightforward.

Grow a Backbone

Unless you’re running vintage electronics, or are an electronics Luddite, your boat probably has an N2K backbone in place already; the N2K protocol has been around since 2001. If you have a chartplotter manufactured in this century with anything connected to it—GPS antenna, transducer, compass—you already have an N2K backbone. (But not radar; radar uses Ethernet cables, not N2K. Some radars are wireless.) If you’re not already N2K, installing a backbone, or expanding the one you have, is fairly easy.

“Backbone” suggests the N2K cable runs through the boat from bow to stern, but that’s not necessarily the case. The backbone is just an arrangement of cables and T-joints; in some cases, it can be just several T-joints attached to each other. Cables and T-joints connect male to female and are secured with a locking collar. Electronics guys call the T-joints “drops,” and the cables that attach the appliances to the backbone at the drops are, not surprisingly, “drop cables.” How many drops the backbone needs depends on the length of the boat, on how many N2K-compliant appliances will attach to the backbone, and so forth. When necessary, you can add to the backbone simply by installing another drop. But all backbones need a fused 12-volt power lead, connected somewhere near the middle of the backbone to minimize voltage drop along the length of the backbone, and terminator resistors plugged in at each end. N2K appliances drawing less than one amp can be powered by the backbone; thirstier devices need their own DC connection.

A digital switching module connects to the backbone via a drop cable. Drop cables can be up to 20 feet long; shorter is better. That gives you latitude to mount the module close to your existing breaker panel and still connect to the backbone. Garmin, for instance, recommends mounting its Boat Switch module on a clean vertical surface, away from possible electromagnetic interference from power cables and electric motors, and where it’s easy to access: If a fuse trips, it’s reset by pushing a button on the module; the digital circuits also have switches on the module should the MFD act up. Easy access to the module makes it more convenient to deal with issues.

Hookups Are Easy?

Mounting the switching module near the breaker panel makes physically hooking up the wires easy: Remove the conductors from the breaker panel and connect them to wiring harnesses that plug into the module, using marine-grade, waterproof connectors or heat-shrink. The Garmin Boat Switch has twenty output circuits, thirteen 10-amp and seven 5-amp, and seven inputs; the inputs can monitor fluid levels in up to four tanks, battery voltage, bilge pump cycling, etc. Every wire is labeled. Once all the wires are connected, hook up 12-volt power through a 50-amp inline fuse, connect the module to ground, plug in the drop cable and, through the magic of N2K, an interface screen will appear on your compatible Garmin ECHOMAP or GPSMAP. Sounds simple, but Garmin recommends having the Boat Switch installed by a professional. The installation manual is downloadable from the Garmin website, so you can read it and decide for yourself.

Once the connections have been sorted out, the system needs to be configured, which can be done mostly on the MFD; you don’t need a computer. There are instructive videos on YouTube. If you’ve connected tank sensors, you need to calibrate each one for minimum and maximum fluid levels, and for the types of fluid in each tank. If you hooked up a livewell, you’ll also have to calibrate the pump cycle settings; the Boat Switch turns the pump on and off at preset intervals. All these set-ups involve grounding various wires for a few seconds at the module, then making adjustments on the MFD. There is also an option to retain physical switches in the circuits, so you don’t always have to go to the MFD to turn things on and off. Okay, this is getting complicated. I think that to get the most out of the Boat Switch, investing in a professional installation will be money well spent.

You can find digital modules from CZone or Maretron with fewer circuits, but at less cost than the Garmin Boat Switch’s list price of $1,000. CZone’s Contact 6 Plus ($415) has six 15-amp output circuits: it can be connected to a waterproof touchpad rather than an N2K-compatible MFD. Maretron’s CLMD12 ($561) has two 12-amp, six 10-amp and four 5-amp circuits. Different modules from different manufacturers have different features and capabilities, too, so before choosing one, check them all out—and make sure the one you pick will operate correctly with your MFD. If your boat has Raymarine’s SeaTalk, you’ll need an adapter to connect an N2K digital switching module. Although all N2K devices should work with each other, make sure before laying out any cash—another reason to involve an electronics pro who can work out the details before they become problems.

Let’s Go Wireless

Whenever anyone mentions “digital,” can “wireless” be far behind? If you have a WiFi-enabled MFD, you can log into its local area network (LAN), kick back on your bunk and control your digital switches on a tablet or phone. If you hear a noise in the wee hours, use your tablet to check the security cameras, and blast the trespasser with the spreader lights. If you’re going digital, might as well go wireless, too.

Or go the whole hog and connect to your digital system remotely via WiFi and your cell phone. Garmin’s OnDeck Hub ($850) and Raymarine’s YachtSense Link ($1,400) are marine routers that switch between cellular, marina WiFi and satellite coverage, improve your connection when you’re on the boat, and connect to the N2K backbone to allow you to watch your boat from afar. The two systems are similar in that both provide remote monitoring of not only the yacht’s systems, but also its location, and will alert you if something’s amiss. Both also have limited output and input channels, so you can monitor vital systems and control a few circuits with your phone. Both routers also use automotive relays (inexpensive and easy to connect) for all but the lowest-demand switched loads.

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The OnDeck can monitor temperature, shore power, battery voltage, security sensors, and onboard N2K sensors. It has five output circuits that can be controlled by cell phone, but when connected to the yacht’s N2K backbone, it can manage Boat Switch-connected digital switches, too. YachtSense Link has four input and output channels to monitor sensors and activate onboard systems. YachtSense Link also connects to Raymarine’s sophisticated Yacht Sense Digital Switching system. Both systems require a subscription plan—worth the twenty bucks a month if you’re alerted to a small onboard problem before it becomes a big one.

Is digital switching something you need? No, not if your boat’s presently wired as you want it, and all systems are functioning as they should. It’s convenient though, and the wireless aspect is a nice perk, especially if you already have a WiFi-enabled MFD. Otherwise, you might do better to save your money for fuel. But if you’re adding circuits, or you’re rehabbing or rewiring an old boat, installing digital switching will give you extra functionality and make it simpler to set-up and connect your DC system. Rather than fishing a wrist-thick bundle of wires hither and yon throughout your boat, you’ll use substantially less wire if you let the N2K backbone do some of the work.

There’s no risk of anyone calling you a Luddite if you go digital, either; that’s worth something, I guess. Let me know how it works out—I’ll be awaiting your call on my flip phone.

This article originally appeared in the May 2023 issue of Power & Motoryacht magazine.

Source: https://www.powerandmotoryacht.com/maintenance/how-to-add-digital-switching-to-your-boat