Digital Switching Made Simple - PassageMaker

Until recently, digital switching has only been available on new, higher-end boats. Today, quite a few systems are on the market for used boats, with more coming. This means that even if you’re not getting a new boat, you can still get a new digital-switching system.

Digital switching is a networked way of replacing conventional DC mechanical circuit breakers and switches. The digital systems are programmable, offering the benefits of automation. They also reduce weight, and place the boat’s switching into a weather-sealed, highly reliable package.

Contact-6-Plus-System-with-Harness

With traditional DC switching and power distribution, there’s a centralized electrical panel with large cables from the boat’s batteries. For each circuit, there is a wiring run from the panel to the point of use. On my boat, this means loads like the freshwater pump, located a few feet from the house batteries, run all the way from the batteries to the panel and then back down to the pump. Power for a load that is 3 feet from the batteries travels through about 20 feet of wire.

And in some cases, wiring grows even more. On my boat, the salon lights can be turned on in two locations. That means there’s wire running to each switch plus another (traveler) running between the switches. Adding another switch to a system like this one can be a difficult, time-consuming task.

A change to digital switching greatly reduces the number of circuits on a modern boat—which can add up to hundreds or even thousands of pounds of wire. Additional switches or other controls, like a multifunction display, instead connect to the NMEA 2000 backbone of the boat, dramatically simplifying installation.

Digital switching circuits also typically bring in a single source of power and then have a single connection to each load. (There aren’t individual connections for circuit breakers, switches and the load.) Most digital switching modules are well sealed against the environment, and utilize solid state switching. Digital modules also offer a degree of reliability that traditional mechanical switching simply can’t match, because a traditional circuit has quite a few connections, each of which is a potential source of corrosion and trouble. Plus, mechanical switches have moving parts that are subject to failure.

Digitally switching circuits opens a world of onboard possibilities. For example, it’s possible to read the freshwater tank level from the NMEA 2000 network and turn off the freshwater pump if the level drops too low. Or, a circuit can be set to turn itself off after a specified delay. Plus, with more advanced digital switching systems, the trip threshold can be set on a per-circuit basis.

Entry-level digital-switching panels are available for as little as $250 for six circuits. I constructed a sample system with traditional mechanical switches for six circuits, and it came to about $200 (sans dimmers). So, pricing on the newer systems has come down enough to be competitive.

In addition, leading companies Maretron and CZone both have digital switching products that can be retrofitted by a pro installer or handy boater, and that are expected to cost less than $500.

Making the switch to digital from old-school mechanical switching like this can spare you from hundreds of pounds of wire.

Making the switch to digital from old-school mechanical switching like this can spare you from hundreds of pounds of wire.

Maretron’s CLMD12 is a 12-circuit digital switching unit. Each circuit has programmable trip thresholds, current monitoring and dimming available. Two of the 12 circuits handle a maximum of 12 amps, six are rated at 10 amps, and four are rated at 5 amps. And each of these circuits can be set to trip at lower current levels—using Maretron’s G2Analyzer software—if a smaller circuit needs to be protected. Maretron expects the CLMD12 to list for about $495, making the per-
circuit cost just over $41.

CZone’s Contact 6 Plus is a $250, six-circuit digital switching unit compatible with CZone digital switching and monitoring products. Costing about $42 per circuit, each of the six circuits in the Contact 6 Plus can handle a maximum of 15 amps of 12- or 24-volt DC. Contact 6 Plus uses ATC blade fuses, which means you’ll need to keep spares on hand in case you blow one. (And consider how accessible the unit is for such replacements.)

To use a CZone system with other NMEA 2000 devices on the network, you will need to build a configuration in the CZone configuration tool and upload it to the CZone components on the network. (You can save the file to an SD card and use a multifunction display to load it onto the network.) CZone offers keypad controls in six- and 12-button versions, in portrait and landscape orientations.

I’ve installed both of these systems on my own boat in only a couple of hours. There is no reason to steer away from one of the lower-cost digital switching options on the market.

This isn’t to say there’s not a learning curve with digital switching, because there is, but the benefits easily outweigh the potential complexities.

Anytime I look at new systems on a boat, I try to answer one question: Will this make boating better, easier or more fun? With digital switching, the answer is a resounding yes.

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