Saturday, March 15, 2014

Offline Charting - Nautical Techie Stuff

A new tool in our kit that we've been trying out this time is a little open-ware chart-reader program called OpenCPN that allows you to load all sorts of charts into it. It is not dedicated to just one set of charts such as Navionics, but instead let's you load downloaded NOAA raster charts or any other chart that has been converted. A little trick we learned is to use another freeware program called GE2KAP (which I think stands for Google Earth to Capture) to download and save satellite views of the areas you're travelling. These views are converted to raster so they are readable by the charting software and when overlaid on the NOAA charts they match exactly - pretty cool! The big advantage is that you've downloaded the satellite imagery so you can use it offline and hooked up with GPS input, you get a really good image of a harbour, can see where the reefs are and have a pretty good idea of what the shoreside is like. Obviously it is no replacement for marine navigation charts and we definitely use those, along with our fixed chart plotter, but as with our handheld GPS it is just one more tool to help you make better decisions about where you go. In particular, this tool is handy in areas that are not so well charted which doesn't currently apply to us, but could come in handy if we head to Cuba or if we ever tackle the South Pacific.

Anchorage at Watermelon Cay in Leinster Bay
Track into Soper's Hole on Tortola - we didn't run over these boats, they're just on the satellite image.
Privateer's Bay on Norman Island, right next to the Caves.

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