Tips and Tricks for Using CM93 V2 Charts with OpenCPN
OpenCPN is a free, open-source navigation program (CPN stands for Chart Plotter Navigator) that's been in active development for several years. You can freely download versions for Windows (all versions, including XP, Vista, and Win7/8), Macintosh, and even several flavors of Unix. It reads and displays several different chart formats, both vector and raster, including the CM93 chart database (v2, but not v3 as of 2015) that covers the whole world. You can annotate charts with new or additional information, lay tracks of where you go, import tracks from other cruisers, plan routes, display GRIB weather data, upload routes to your GPS and/or autopilot, etc. It does a wonderful job with AIS, as the alarms can be extensively programmed.
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What we do on OcelotWe've been using OpenCPN since 2010 (when they added Chart Quilting) and are very happy with it. It is constantly under development so new features are being added by a dedicated team, many of whom are also cruisers. Features can be requested and all such requests are seriously considered. There are several active discussions on Cruisers Forum where features and/or problems are discussed and solved (the developers respond personally). New releases come out once or twice a year and since the software is "open source" all new versions are also free. In fact, you are free to download the source code and add new features yourself if you want to.
How to use GE when you're offline:When you go to new places with GE, it has to download the information it displays from the Google servers. These are fairly large graphical files, so it can take some time, even with a broadband internet connection. GE displays a little circle in the lower right corner of the GE window, to show download progress. When the circle completes (and turns color) then you know that the download for a given view has completed, and you can move on to your next view. But to save time (and internet bandwidth) GE caches (saves) this received information on your computer. So going back to somewhere you've already been to displays very quickly, because the information is coming directly from your own hard drive.