Champagne Electronics on a Beer Budget
With a bit of ingenuity, research, and know-how, a cruising couple builds a state-of-the-art package for less than $2,000. "Electronics" from our March 2012 issue.
Once we’d built the redesigned nav station, it was time to install and test the electronics. Each unit has NMEA input and outputs. I have to admit that my first reaction to the complex of wires and routing was unprintable. For example, here’s the wiring array just for the LS4100 depth sounder: Red (positive from battery), Black (negative from battery), Silver (wire shielding), Blue (transmit NMEA; A), White (transmit NMEA; B), Yellow (receive NMEA; A), and Green (receive NMEA; B).
In a system like this, there are two ways to move information, in series or in parallel. For example, in a series, or daisy-chain, installation, the NMEA OUT from the GPS might be connected to the NMEA IN on the fish-finder. The DB9 connector for the serial-to-USB adapter would then carry the NMEA OUT data from the depth sounder so that the PC would receive both the GPS and depth information. If we were interfacing to the PC with a simple serial-to-USB adapter, this would’ve been the best approach. However, in our example, the problem is that the PC won’t get GPS NMEA information if the depth sounder were to be turned off or broken.
In the parallel installation we utilized, the PC has the ability to receive and transmit data from up to four distinct inputs via the four-port serial-to-USB adapter. In our case, three separate instruments can pick up the GPS data output by physically connecting them together on a terminal strip. This allows the VHF, the PC, and the depth sounder to receive GPS data.
Once the GPS, the fish-finder, and the PC were all talking, it was time to add the VHF and the A.I.S. The Standard Horizon GX2150 VHF with A.I.S. is a rugged and intuitive submersible unit that used our existing VHF antenna to pick up A.I.S. signals being transmitted from vessels in our vicinity. Once it receives GPS input, it shows adjustable range rings with digital selective calling capability to each target on the screen. We also opted for the Standard Horizon RAM3 Remote Microphone for cockpit use, which displays the same information and also allows access to the radio functions. When it’s connected to the PC, we also get full A.I.S. targeting information on the chart program.
Following simple downloaded instructions, we installed Ubuntu, a free Linux operating system, and OpenCPN, an electronic-charting application that’s quite good. OpenCPN will run on a variety of operating systems and is also freeware. While it doesn’t yet have the slick interface and all of the bells and whistles of some of the established chart software, such as Expedition, it meets our requirements, including showing A.I.S. data on the charts.
Our only issue with OpenCPN is that it doesn’t support “Furuno talk,” so the GPS won’t accept routes uploaded from the PC. To address this, we export the route to a file on the PC, then upload it to the GPS using GPS Utility, another freeware software package. Raster charts can be downloaded at no cost directly from the NOAA website. If you’ve purchased vector charts, these also work.
The table below, “Lyra’s New Power Requirements, Measured by a Link 10 Battery Monitor,” lists our very modest power requirements and a number of the configurations that we use to minimize onboard power consumption.
While we’re very satisfied that we inexpensively built a serviceable navigation system aboard our boat—it works flawlessly, we enjoy its easy operation and the ability to tweak power consumption, and we feel that the time spent sourcing and installing the system was worth it—we realize that our solution won’t work for everyone. But if you’re on a tight budget and can spend the time to research, troubleshoot, and install the gear, we believe that our approach represents a viable alternative.
Green Brett has been sailing and living aboard since childhood, and shares his love of cruising through his company, On Watch Sailing charters and instruction, based in Newport, Rhode Island.