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Distributed Power Systems

The cutting edge of integrated yacht technology is distributed power—and it is sharp.

July 16, 2010

Intelligent Electricity

It’s likely that your electric windlass and/or bow thruster has already given you a taste of what’s called distributed power. The thick cables needed to carry the DC juice usually run directly from a battery bank through a large fuse to the power-hungry motor, not via the switch or joystick at your helm. Thanks to a relay those controls use light wires, and hence extra controls, even wireless ones, are easy to add. But it’s also likely that the full load of most electrical gear on your boat is cabled to a large central circuit-breaker panel and then out to where it’s needed. The various distributed power systems now being built into many new yachts, and retrofitted into a few older ones, aim to eliminate those panels, and to create many bonus features in the process.

One hallmark of distributed power is remotely controlled breaker modules efficiently distributed close to where they’re needed around a boat. The overall reduction in cable mess and weight can be profound. Moreover, the circuit protection and switching is not done by a simple fuse and relay, but rather by a modern solid-state innovation called a MOSFET (for “metal oxide semiconductor field-effect transistor,” if you must know). MOSFETs can be set up, switched, and diagnosed by a few data bytes running through a network bus, and they also can both control and sense the amount of current passing through. Mix in a few microprocessors with some clever programming, and the magic begins: A distributed power system, for instance, can keep track of how often and how long the bilge pumps run, and can also broadcast an alarm around the vessel—maybe even off the vessel—if one of them is clogging up, as that situation will cause a higher current draw.

Thus distributed power is alternately identified as intelligent, digital, multiplexing, or some combination of those buzz words. And the various manufacturers who have bravely entered this complex niche, but can’t reach consensus on what to call it, will no doubt come up with more terms before the technology settles out. It’s already clear, though, that once you electronically manage a yacht’s electrical system, there’s virtually no limit to what’s possible. For example, MOSFET digital switching and current control abilities mean that whole-cabin dimming is relatively easy, and whole-boat “scenes” are possible. Consider a night running mode in which courtesy, chart table, and navigation lights are all activated with a single command, and you’ll be informed if one of the latter’s bulbs blows. Other scenes might have roles for electric blinds, power hatches, HVAC, lava lamps…whatever!

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Consider, too, that such commands can emanate from traditional-looking switch banks, even if complex scenes have to be set up with a PC or one of the dedicated touchscreen PCs usually available in higher-end systems. That’s because all distributed power schemes include digital-switching modules and/ or interfaces able to incorporate dumb switches into a smart network. And while distributed power networks are innately good at monitoring a boat’s electrical flows, it’s relatively easy, and advantageous, to integrate sensors like those minding tanks and batteries and even those involved with security, navigation, and more. If there’s a GPS in the system, it can know when to turn on the anchor light. A diesel day tank level falling below 20 percent can trigger a system wide message and set up a pumping routine. An activated motion detector can flash the deck lights.

Automated load shedding is one of the most interesting, and advanced, distributed power capabilities. The concept is to avoid overloading DC circuits, shorepower connections, or a generator by temporarily turning off appliances like water heaters and refrigeration when more urgent demands come online. As with the Victron inverter/charger, this sort of intelligent power management also means that battery banks, generators, and dock cables can be scaled more efficiently. But this is also a good time to note that MOSFET technology is not yet practical for marine AC. OctoPlex—the design adopted by several top builders like Viking Yachts and Ocean Alexander—surmounts this problem with solenoid-operated AC breakers and conventional load sensors, but most distributed power systems control only DC circuits at this point, though conventional AC monitoring is typically included. (Also worth noting is that Paneltronics [www.paneltronics.com] just introduced a standalone AC loadshedding system for midsize yachts.)

OctoPlex was also first to use NMEA 2000, the marine electronics data sharing and cabling standard discussed here last month, for its bus. But the next step— one that turned many heads at the winter shows—came from Simrad and BEP. The former’s NSE multifunction display series (www.simradyachting.com) now integrates over NMEA 2000 with the latter’s new CZone distributed power system (www.bepmarine. com). This means that many of the features discussed above, like lighting scene controls and bilge pump monitoring, are now available front-and-center at the helm of a modest- size yacht. And mind you that these are still “wow” features on a big yacht with, say, OctoPlex touchscreens mounted alongside a glass bridge.

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Meanwhile, Maretron (www.maretron.com)—already a leader in NMEA 2000 sensors, and a corporate relative to OctoPlex developer Moritz (www.moritzaero.com)—is definitely developing its own digital switching system (though nothing has been announced yet). And Simrad’s relative Lowrance (www.lowrance.com) has teamed up with Digital Switching Systems (www. digitalswitchingsystems.com) to integrate that firm’s fishboat- and tender-scaled products with HDS displays. Plus, when I recently visited Garmin (www.garmin.com) and asked its lead marine engineers about the possibility of distributed power integration with their helm systems, they grinned and said, “That would be interesting.”

Distributed power systems are certainly exciting, but a prospective owner should look carefully into what could go wrong. The answer—given technologies that can potentially affect everything that’s powered, and that are quantum leaps more complicated than standard boat wiring, dumb and inefficient though it may be—is lots. You’ll want to know about backup circuit protection and switching, and whether the latter fails to its existing on/off state if the module has problems. The “brains” of the system should also be replicated around the network so one module failure doesn’t cascade into many. The manufacturers have certainly done a lot of work regarding these issues, which is one reason why these are such hard systems to develop. Which, in turn, is why you should also look into the track record and stability of the manufacturer.

In fact, just recently it was announced that a system I would have featured here, E-Plex, is going out of production, though it can be seen on several well-known production yachts. The manufacturer, ED&D (www.edd-tech.com), says that there’s more to the story, which I’ll certainly follow on my blog, but I can’t help but think about the 60- foot catamaran Mala Conducta, probably the most innovative custom yacht launched in Maine last year. She is spider-webbed stem-to-stern with E-Plex modules, displays, and networking, and I’m told that the owner and crew are pleased with how it all works. But I’d guess they’re now scrambling to stock up on spare parts, and maybe even forge a personal relationship with an ED&D engineer. Distributed power is the cutting edge of marine electronic technology, but as we know, that has the potential to draw blood.

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