Project: Computer Central

Computers seem to be omnipresent in today's world and Daydreamer's certainly no exception.  While we carry paper charts and a sextant, a computer's convenience and utility in difficult or stressful navigational situations argues strongly for an onboard computer.  They're an absolute necessity if we are to have email over HF radio, such as Sailmail or Winlink.  In marinas, dockside access to the internet via WiFi or dialup connection has become very common and that capability is very valuable, particularly when checking the weather prior to departure for a passage and VOIP services, such as Skype, can make phoning home almost painless.  AIS can help avoid a difficult and potentially dangerous situation, as we found out one dark and stormy night outside Moreton Island.  And I found CAD (computer-aided design) to be invaluable when designing a replacement fuel tank ... I'm sure it saved me thousands of dollars by allowing me to do the design myself and to act as prime contractor and installer.

Indeed, many cruisers seem to have come to a similar conclusion and a laptop at the nav station is now a common sight.  After weighing the pros and cons, we decided against using laptops for our main computer; while they have a relatively low power draw, they're more expensive, difficult to repair and upgrade, use hard-to-get specialized components, and are inconvenient in use, monopolizing space at the nav station.  But the laptop's biggest disadvantage is its very limited connectivity.  They often don't have even one COM port nowadays, forcing the user to rely on potentially problematic USB/Serial adapters.

Our first computer onboard was a medium-sized inexpensive tower that used a conventional ATX motherboard and Pentium II CPU, 40 GB hard drive, and CD burner.  It eventually became outmoded and was replaced with a small form factor (SFF) computer in 2004.  While satisfied with the computational power I had at this point, I still sought a way to reduce the overall power consumption.  The computer drew more than a little power on it's own and the required inverter just added to the power consumption and radio frequency noise.  About a year later I became aware of a very small motherboard form factor, the mini-ITX , which used very small cases that could be powered directly from DC.  It was a natural fit, so I replaced the SFF with the smaller 12V powered computer that can handle AIS and autopilot control.  

A lot of folks seem to be concerned about the reliability of electronic devices in a marine environment.  In my 11 years of non-marinized onboard computer usage, I have not had any failures on board.  (The one problem I DID have was a motherboard failure when the tower was being used in a house we had rented in New Zealand - maybe a power surge? - but $30 for a replacement motherboard on eBay put us back in business.)  I protect the computers from drips and spray by enclosing them inside cabinetry, which BTW is much harder to do for laptops.  When not in use, the keyboard is stowed on a protected shelf and the mouse, which has made a number of death-defying leaps onto the cabin sole, now has a dedicated storage spot to keep it safe.  In fact, the keyboard, mouse, and monitor are the original ones I started out with so have been in almost daily service for over 12 years!

Current built-in computer is a VIA Mini-ITX EPIA-PD motherboard in a Travla C128 case (4in H X 8in W X 8.5in D).  It is equipped with;

While not a powerful computer, it has more than enough grunt to handle routine navigation tasks.  Graphics-intensive multi-tasking will slow it down discernibly.  Because of its miserly DC power consumption, it does not draw much current and the CPU runs cool enough to not even need a fan. 

The mini-ITX computer normally handles navigational duties when we're underway.  HF email is a dedicated service for this computer and it's the main computer we use when anchored out due to its low power draw.  When away from the dock, this computer also handles weather satellite images, which we can download directly as the satellite passes overhead.

12V DC power draw is 2.6 amps + 1.3 amps for the monitor &background services such as AIS.  Dedicated services are Pactor III modem interface (for HF radio email and weather fax) and weather satellite image processing.

The monitor requires 14.6V DC and the power supply in the Travla case is similar.  A small dc/dc converter, typically used to power a laptop from 12V DC, provides 15V DC for these services.  Background services, always powered up, include this dc/dc converter, the AIS receiver, and the KVM switch, which together draw just over 500 ma.  The monitor adds another 800 ma for a total draw of 1.3 amps.