Monday, November 3, 2014

Crazy FREE Charts

One of the smaller blessings of traveling by boat in the United States is that all the necessary nautical charts are free. Most everywhere else in the world obtaining digital charts is equivalent to paying for the birth of your first born (or second, etc.) One of the great things about the Internet is that creative people from around the world donate time and expertise to creating really cool software. Enter Paul Higgins from Canada. In his sailing experience he noted that many of the electronic charts were based on very old surveys. Surveys that were sometimes several nautical miles wrong. When going into Turneffe Atoll in Belize I noted that the channel I was in was shown about 1 NM north of my location on the chart plotter. Then I check the chart and found the last survey was in 1899, Not surprising there was a small error.

What Paul has done is create software that converts a Google Earth image into a .kap file. In the process one can merge a nautical chart with the satellite image. The result is that when you load the .kap file created into OpenCPN the satellite image is displayed in the chart plotter. That big brown section of land is all of a sudden converted to a beautiful satellite image! The article that explains how to do this is here (Click Me!) With good charts (like the US charts) things line up. Other places not so much - which is the point of the exercise.

A couple of comments:

1) Getting the software downloaded is pretty easy, but getting things to work is a bit more difficult.
2) There is a little arrow on the right edge of GE to KAP. You must click on this arrow if you are trying to build an overlay of both the land (Google Earth) and the ocean (OpenCPN Chart)
3) On the right hand pane find the "Overlay Chart/Image or OpenCPN pull down and set it to OpenCPN. This will switch the program over to creating a hybrid chart of both land and water. It will also change the instructions in the left hand pane.
4) Note that Google Earth has to be set for "Decimal Minutes." This is done in the Google Earth "options" pane.
5) The computer will open lots of windows, do all sorts of crazy things. At one point you will have to click an OK button for the process to continue. Don't touch anything else until the program finishes or the process will fail.
6) Once the chart(s) are created you will have to refresh the database in OpenCPN (Options - Charts) to pick up the new chart. It will show up as a blue bar at the bottom of the OpenCPN chart window.

Note: There is a very nice Google Earth plug in for OpenCPN. However, I believe you need to be connected to the Internet for it to work. Obviously when one is offshore this is not going to work but it is great for planning purposes.

Fair winds and following seas :)

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