Chartplotter on a shoestring

FOR many years I have been using a variety of laptop and tablet computers to run chartplotting software.

The laptop arrangement has the great advantage of being able to have a back-up at a reasonable cost, not to mention portability. I have taken my laptop(s) and tablet on other peoples’ boats when crewing/navigating.

The software I am using is free, but the map license costs a moderate amount. Charging for the chart information is a common arrangement in the industry. My current licence allows installation on two Microsoft, two Android and two Mac platforms. The most generous of all the licences I have seen.

The electronic charts are raster copies of paper charts, so they are familiar when shown on the chartplotter. Sometime it is necessary to manually zoom in or out to see the chart of interest. Very similar to real charts.

Using this system, I would normally have a laptop secured to the navigation table and a tablet in the cockpit running the same software for ready reference. The laptop is capable of listening to data from the AIS and display a chartplotter overlay.

This particular app seems to have a permanent problem that requires filtering some AIS sentences using a thirdparty app, before the AIS data displays reliably. A hack that is confusing to new watchkeepers and should be unnecessary.

The trouble with this setup is that it takes up all my navigation table and it needs more ship’s power than I would like. That said, I have never flattened a battery.

Also, the cockpit tablet does not have the ability to display AIS information. Neither device can display GRIB weather overlays on the chartplotter.

Something I have always hankered after because the coast outlines on the GRIB apps are usually to a small scale.

Despite the apparent flaws I would not leave home without these devices, but I am always on the lookout for a better way at a moderate cost.

WHAT IS OPENCPN?

A recent Cruising Helmsman article mentioned OpenCPN in passing. ‘Doctor Google’ revealed an attractive piece of kit.

‘Open’ means that it is open software. That is, the source code is available to anyone to further develop/review/repair. The ‘CPN’ stands for