OctoPlex, the three cable boat, and NMEA 2000

I mentioned OctoPlex when it received a special mention at METS; now I’m trying to write a column about it and the whole coming revolution in marine power systems. It’s not coming easily, I’m way past deadline, and so this will be short! Here’s the deal: electronic circuit breakers combined with data networks like NMEA 2000 mean the end of conventional circuit breaker panels. The concept is often called “distributed power” but Nigel Calder also uses “the three cable boat” in a series of articles he’s done recently in Professional Boatbuilder, Sail, and Yachting Monthly (none, unfortunately, online, but look down this page for Nigel’s pithy answer to the question “should I try this now”)). In its simplest form plus and minus cables carry power around the boat, teeing off wherever needed to an electronic circuit breaker (ECB) which is controlled by the third (data) cable. ECBs are also known as MOSFETs and they’re complicated animals, but have features like the ability to constantly measure voltage and amperage and even modulate amperage (i.e. dim light circuits). Combine those features with networked, microprocessor-based switching—and, hey, you might as well throw in tank, bilge, etc. monitoring since you’ve already got the network and screens—and you start getting something as powerful as OctoPlex. Check out a much larger version of the schematic here. This system can automatically shed power loads, protect individual circuits against brown out, setup custom dimming programs, tell you if a nav light blows out, and so forth…sky’s the limit. But can things go badly wrong on the three cable boat? Hell, yes! Which is why OctoPlex is redundant every which way. More on that later.