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Electronics

Personal Computers at Sea

PCs at Sea

These computers may be indispensable ashore, but can they really cope with the rough-and-tumble of life and work afloat?

I’ve never been much in favor of using “office equipment” onboard a boat.

It’s fine to use a laptop to do a bit of Web surfing, send a few e-mails, or play games, but navigation, communications, and engine management are different. For those, I want the proper equipment. But when you see 12-inch MFDs at about $4,000 while 15-inch laptops sell for $400 you have to wonder whether having a proper chartplotter and a real radar display in the wheelhouse really makes sense—or are they simply expensive luxuries?

A growing number of companies and their customers don’t see PC navigation as a low-cost alternative at all, but as a better option than conventional marine electronics. PC-based onboard systems, they say, offer greater performance and versatility, and if they also provide more screen space per dollar (which they generally do) that’s just a bonus.

So what is it that makes a marine personal computer ready for life at sea?

Waterproofing is not only expensive, it poses technical problems too, because it requires a fully sealed case, which makes it difficult to get rid of the heat generated by the processor. Fortunately, there aren’t many boats that need a truly waterproof PC. Even on a walkaround, it’s almost always possible to find somewhere onboard that is dry enough for a non-waterproof PC.

A more serious problem than dollops of running water is the effect of long-term exposure to a damp and salty atmosphere. One line of defense is a “conformal coating”—a silicon “varnish” or “lacquer”—to protect entire circuit boards and the delicate components that are mounted on them. It can be very effective, but it’s a difficult and expensive process and it makes servicing, upgrading, and repair more difficult.

Doing without a cooling fan and fitting filters to the ventilation holes achieve relatively economical and simple protection. Restricting the ventilation limits the designer’s choice of processor (and limits the potential performance of the entire computer), but it also minimizes the damage that would be caused by having a continuous stream of damp, salty air flowing across the motherboard.

Movement, vibration, and pounding will kill a normal PC at sea long before corrosion does, so although it may be okay to balance a laptop on the chart table in the marina, long-term use demands that a marine PC must be bolted down, with its cables and connectors secured in place and with clamps or cable ties that absorb the physical strain.

But there’s not much point securing the computer if the manufacturer hasn’t taken similar precautions inside it by minimizing the size of circuit boards to stop them from flapping around when the boat hits rough water and providing additional support for large components.

Hard disc drives are particularly vulnerable to impact. The traditional solution has been to mount them on shock-resistant mounts within the case, but solid-state hard drives are becoming a more and more popular alternative.

The next biggest issue is probably the power supply. The problem is simple. Most PCs are designed to run on a 120-volt A.C. supply. Most boats aren’t.

The funny thing is that the components inside even an office PC are designed to run on low-voltage D.C. power created by a power supply module inside the casing. The obvious, but inefficient and potentially unreliable solution, is to use an inverter to create “mains” power from the boat’s 12- or 24-volt D.C. supply, and let the computer’s power supply module convert it back into the range of D.C. voltages required by the computer’s different components. But a much better alternative is to use a D.C.-to-D.C. converter in place of the computer’s regular power supply and hard-wire the whole thing into the boat’s D.C. system.

Power, of course, isn’t the only thing that is going into a PC. Even in this so-called “wireless” era, there are nine separate cables going into the back of my office desktop. A marine PC may not need a printer or a hard drive, but it will certainly need some kind of mouse, a keyboard, probably a GPS receiver, and possibly other marine sensors or an NMEA 2000 network. There are adapters around that will convert almost anything to USB, but marine PCs are quite likely to be offered with internal GPS receivers, dedicated antenna sockets, NMEA ports, and other such ancillaries.

Once the manufacturer has built a PC that is designed to survive the marine environment, handle marine power supplies and accept marine data, it’s then up to us—the users—not to muck it up. Paul Sumpner of Digital Yacht is pretty clear about how we can significantly improve (or wreck!) our PC’s reliability. He recommends using Windows 7 and making sure that you’ve installed the very latest drivers for any devices connected to the PC.

Other than that, though, he suggests that once you’ve got the computer system working, you should just leave it alone. “Avoid installing and uninstalling lots of different software,” he recommends, “and if possible avoid having an Internet connection on your navigation PC. Keep your boat PC for navigation, use an old laptop or cheap netbook for surfing the Internet and playing games.”

Which almost brings us full circle: If we have a PC that doesn’t double up as a Web surfer, word processor, or game console, is it really fair to classify it as a piece of office equipment? Or can it take its place as a dedicated marine instrument, an MFD, but with a particularly open architecture and your choice of software?

This article originally appeared in the March 2011 issue of Power & Motoryacht magazine.

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