Friday, March 21, 2014

Electronic charting on Estrellita: SAS Planet & OpenCPN

The electronic charting world continues to evolve, with the cruising sailor a prime beneficiary.  Livia and Carol, living aboard s/v Estrellita and (currently) cruising in French Polynesia show us a couple of free charting programs that they use while cruising in reef-strewn waters...
(Please click on image for full-sized versions -Ed)

This is what the split screen on our netbook looked like when we were making landfall and first anchorage at the town on Rikitea Island, in Mangareva Atoll, in the Gambier Archipelago, French Polynesia (whew! big name, small place).

SAS Planet (on the left) is a neat bit of freeware that allows you to use satellite imagery, from a variety of sources, with a GPS plugged in. It was passed to us on a hard drive but you can download it here. You accumulate a cache of satellite images while you are online. These caches can also be passed around so that the same images don’t have to be downloaded on the slow internet connections in the islands by every cruiser.

SAS Planet allows you to download satellite imagery from various sources including Google, Yahoo and Bing. Because these sources aren’t identical this is very useful. For example, if the Google image for the anchorage you want has a big cloud in the middle, you can try the Yahoo or Bing image – all from SAS Planet.

You can make tracks, and import and export tracks, routes and waypoints in the commonly used .gpx format. There are a few things I find awkward, such as the fact that the measure tool will only give metric measurements (not nautical miles) and that you have to actively save a track before you close the program otherwise it gets dumped. Also, Google will sometimes lock you out, stopping your ability to download their imagery, if you download too much at once. Still, overall a great piece of freeware.

Having satellite imagery while offline was revolutionary for us.  If you like to pore over images to find out of the way anchorage possibilities, to imagine routes through reef laden areas that will allow you to go somewhere that other people are not going, satellite imagery in some form is the ticket. We had previously tried the Google Earth plug in for OpenCPN and, at least at that early stage of development, found it cumbersome. Take a look at the difference between a CMAP chart and SAS Planet in this close quarters reef navigation (yes, yes, we used our eyes as primary).

(Please click on image for full-sized versions -Ed)

OpenCPN (in image above on right) in its newest iterations is a very useful piece of software. It is not as slick as our previous (purchased) navigation software (NavSim’s SailCruiser), but, well, it’s FREE. I love the flexibility and customizability of it. Importing and exporting tracks, routes and waypoints between our various programs is easy. Almost everything in the program can be customized or turned off or on. The plug in we find most useful is the GRIB visualizer. The older versions of OpenCPN worked with a Fleet Nadi plug in as well but we haven’t been able to find that plug in for the newer versions so we are currently running an older version because we download the Nadi Fleet Code regularly with our SSB.

In order to run both programs simultaneously with one USB puck GPS, we downloaded and installed Franson GPSGate. This allows us to take the single COM port created by the GPS and turn it into a bunch of virtual COM ports which can then be assigned individually to any program that wants one.

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