Simple systems: It's about design, not quantity

What do we mean when we say a boat's systems are "simple"?

There's a temptation, at times, to say that simplicity is about cutting back. About leaving out whole systems to save on installation and maintenance dollars. I don't think that's really what it's about.

What we're really looking for when we say "simple" is, more often than not, elegance. Maintainability. Reliability. The least complex, least costly way to fill a stated specification. The ability for the captain to understand, and repair, every system on the boat.

An example

I recently designed an electrical system for a client who's hoping to live aboard full-time, hopping from country to country as the seasons dictate. As we discussed the boat's equipment list and the expected usage of each device, the daily demand inched up towards 6 kWh/day on passage, 2 to 4 kWh/day at anchor.

The yacht's not exactly loaded down with luxuries, but she has everything you need to live aboard in the same standards of comfort we're used to at home in North America. Refrigerator, small TV, office with computer and peripherals, watermaker, running water, plenty of lights and fans. Plus the big boat-specific loads, things that make it viable for a small crew to handle a large yacht – radios, radar, instruments, oversized windlass, an autopilot strong enough to keep her on track right up to the point where you drop a drogue off the stern.

On a 12 volt bus, consumption would peak at close to 500 amp-hours a day; on this boat's 24 volt bus, peak demand comes close to 250 Ah/d. You're talking eight 8D batteries to provide that kind of juice, with 30-plus breakers on five panels – hardly "simple" in the reductionist sense.

And yet, I consider the resulting design to be straightforward, elegant, simple and maintainable. Why?

  • Every circuit is easily traced. There are no weird ground loops, shared circuits, or other hard-to-maintain oddities. Anyone who knows how to use a multimeter can understand the system well enough to track down the location of almost any potential fault.
  • No unnecessary computerization. The only microcontrollers in the system are the ones embedded in the battery monitor instrument and the charging regulators. There's no need to program or configure anything while installing or repairing the system.
  • More, smaller panels are more practical than a single big panel. A typical yacht wiring system requires you to power down the whole boat to work on the main panel. Small sub-panels, each with their own main feed, allow you to keep the lights and pumps on in the rest of the boat while you work on one panel. By opening one switch, you can isolate the solar, wind and alternator regulators from the battery, allowing you to replace a damaged component without fear of shorts and sparks – and with the lights, fans and other systems still live, so you can see what you're doing and stay comfortable while you work.
  • No AC shore power. The shore power connection is often a nightmare of corrosion, ground faults and frustrating "what the !@#$ is going on here" moments. A boat with a self-sufficient DC system can leave out shore power entirely – or, optionally, route it only to a completely isolated battery charger.
  • Worry-free. There's enough battery capacity in this system to ride out four or five calm, cloudy days at anchor (no solar or wind charging) before you have to think about starting the engine for charging. That same reserve gives you confidence that your autopilot isn't going to drop dead for lack of juice when you're riding out nasty weather offshore. Knowing that you can fix almost anything in the electrical system yourself, without having to call in a technician, helps many skippers sleep well at night.

No absolutes

Some skippers will look at that and say "My gosh, that's far too much stuff. I don't need the office, the autopilot, the fridge." That's perfectly OK. The same design philosophies can be applied to a more rustic lifestyle.

Others will say "Where's the air conditioner? The stereo? The satellite reeceivers? The ice machine?" That's also OK. Your electrical schematic will span many more pages, but each individual circuit will still be simple and easily traceable. You'll have more solar panels, more batteries and a bigger alternator, but the principles of caring for them and troubleshooting them will be the same. You'll have a lot more wiring, and we'll be careful to separate it into logical, easy-to-follow bundles so you can tell what goes where.


Personally, I like designing, building and installing things, but I don't really like ripping them out for repair. I'd rather spend 20 hours at the drawing board and 200 hours installing things properly (with an eye to a 20-year operating life) than spend 100 hours to hack together something that's good enough for now but will need to be ripped out and replaced in 10 years.

Then again, I'm the kind of guy who gets frustrated when he discovers that there's no way to replace the onboard battery of a 9-year-old camera. Perhaps I'm a bit nostalgic for the days of over-engineered stuff that just wouldn't die, ever. Perhaps it's just the German ancestry in my family. Whatever the rationale, my design philosophy focuses heavily on simplifying things, looking for the clean and elegant solution, taking the time to get the design exactly right, and ensuring that it's maintainable for the long term.

So, when I say "simplicity" with regards to systems, now you have some idea what I mean.



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