Sailing to the British Virgin Islands in the Caribbean 1500

How To Make A Track Map For Google Earth

 
Click the image to launch Google Earth and display a track map of our voyage. If you don't have Google Earth on your computer, there's an internet link at the bottom of this page to download a copy.   Click the image to launch Google Maps in your browser window and display the track map. This option is available for people who don't have Google Earth installed, however Google Maps is much slower than Google Earth when displaying lengthy tracks.

By the end of our voyage on Night Heron, we had accumulated several pages of log sheets containing our hourly position fixes. These fixes were obtained by reading latitude/longitude from a GPS, then writing the numbers by hand on a log sheet, along with the date and time. We used several GPS units, including the main Furuno Navnet chartplotter and a couple of handheld GPS units. We used the handheld units while the main chartplotter was turned off to conserve electricity.

Any of the GPS units (including the chartplotter) could have been configured to save an internal track log, which could then be downloaded to a PC for later display. There were a few problems with this approach. First of all, we didn't keep any of the GPS units powered-up continuously during the trip, so there would have been gaps in any track log. The main chartplotter was turned off for long periods of time to conserve electricity, and the handheld GPS units were only battery powered, and thus couldn't be powered-up continuously. Also, on a voyage of unknown duration, it might be tricky configuring a GPS track log to avoid overfilling the track log memory and thus losing data. That said, any of these problems could have been solved easily enough if we had wanted to keep a continuous GPS track log.

After we arrived at Tortola, I photographed the log sheets to get a copy of all the position information. Back at my computer in Maryland, I wanted to create a track map for my web site to show Night Heron's route. This required some fiddling and futzing, but I finally figured out how to make a pretty nice track map.

The basic process of making a track map has several steps:

  1. Capture all the raw position information in a text file.
  2. Import the text file into a spreadsheet, then create the desired display format for the position information. Save this information in a new file, in a format known as "comma-separated values" (abbreviated CSV).
  3. Edit the CSV file in a word processor to strip off unneeded information.
  4. Read the CSV file into another spreadsheet and add annotations required by GPS Visualizer (more on this later). Save the annotated spreadsheet in a new CSV file.
  5. Go online and process the annotated CSV file using GPS Visualizer. This is a free online application that converts a CSV file into a file that can be read by Google Earth to display a track map. GPS Visualizer creates the new file on its server, which you then download to your computer as a KMZ file (Google Earth's native file type).
  6. Open the KMZ file in Google Earth then debug and clean up your track map.

As usual, the devil is in the details, so I've included detailed instructions below:

  1. Capture all the raw position information in a text file.
  2. Import the text file into a spreadsheet, then create the desired display format for the position information.
  3. Edit the CSV file in a word processor to strip off unneeded information.
  4. Read the CSV file into another spreadsheet and add annotations required by GPS Visualizer.
  5. Go online and process the annotated CSV file using GPS Visualizer.
  6. Open the KMZ file in Google Earth then debug and clean up your track map.

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