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12-volt computing

Mar 25, 2016

An automotive computer at the nav station makes sense for voyagers

A computer designed for automotive applications runs on 12 volts.

A computer designed for automotive applications runs on 12 volts.

Most cruising boats have computers on board these days. They serve to display charts, connect to the Internet, check email, etc. Some of these are desktop computers and some are laptops. 

For example, for the longest time we had a laptop on board. At first this was a necessity since you actually had to carry it ashore to plug into a phone line to check email. As Wi-Fi and cellular access have evolved, however, the need for a portable computer is gone. Still, they’re convenient, small and economical, and so they remain.

But powering the laptop has always bothered me. I mean, you start with massive 12-volt house batteries — a constant and secure source of power — then convert those to 110-volt AC through an inverter that you switch on and off as needed. The laptop plugs into the AC and the power supply converts that back down to a steady DC, generating heat and wasting precious electricity, before once again charging another battery in the laptop.

This chain of conversions is not exactly the pinnacle of engineering efficiency.

So, a couple years ago I replaced my once-again aging laptop with an automotive computer. Not the kind that controls your fuel injectors or air conditioning, but an honest PC built for automotive applications. I got mine from Logic Supply (www.logicsupply.com), though there are other vendors out there as well.

Computers built for the automotive market use a conventional PC motherboard that is designed to operate under an extended temperature range. Basic models cost about the same as a laptop but, unlike common laptops, automotive computers are designed to operate at temperatures above 122° F (50° C). Generally they are fanless, and if you get one with a solid-state hard drive it’ll have no moving parts at all.

The computer unit can be tucked out of the way.

But the best part of an automotive unit is that they run on a DC supply voltage, just like a car. No more inverter, no more extra battery. Mine even came with an “ignition switch” connection that puts the computer to sleep and wakes it up again. I’ve wired the power to a separate circuit breaker on the house battery bank and the ignition wire to a switch accessible at the chart table.

The computer is smaller than my old laptop, so it got mounted temporarily in the same place at the chart table. I’ll eventually move it so it doesn’t take up that space anymore. The laptop had to be easily accessed; this computer, not so much.

Since it’s a PC, it runs Windows or Linux and it has enough USB ports for Wi-Fi, printers, keyboards, etc. Mine came with two native serial ports as well — something you don’t see on laptops very much anymore. I’ve got a Wi-Fi adapter with an external antenna for connections in marinas or to my cellphone, and a wireless keyboard and mouse that I can easily stow when not in use. The screen is an old 17-inch display monitor that I built into the chart table back in the laptop days.

This was an easy transition to make. Since we already had the external monitor and keyboard/mouse, it was as close to plug-and-play as it can get.

And I get that satisfaction about the whole battery-inverter-charger-battery thing.

Contributing editor Jeff Williams completed a circumnavigation with his wife Raine on their J40 Gryphon. They still sail in their current home of New Zealand.

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