Chartplotting on a budget

The GPS unit and OpenCPN

I've just bought a "GlobalSat BU-353 WaterProof USB GPS Receiver (SiRF Star III)" for $36.95 from Amazon. Its smaller than it looks online, comes with an optional suction cup and also has a magnetic base that will hold it onto things as small as a screw. I couldn't get reception in my office (there's a floor above mine) but worked great in my home.

I've installed OpenCPN from:
http://bigdumboat.com/cpnindex.html
http://opencpn.sourceforge.net/
which is a free open source chart plotter and will load raster charts from:
http://www.nauticalcharts.noaa.gov/mcd/Raster/index.htm
and vector charts from:
http://www.nauticalcharts.noaa.gov/mcd/enc/index.htm
I downloaded the entire set of NOAA vector charts in about an hour and they take up about 1Gb when uncompressed.

I had to tell OpenCPN which COM port the GPS was on, tell it the directory where the charts I downloaded where and then wait a couple of minutes while it digested them.

All in all, pretty painless.

Its got some nice features:

• displays plots of tidal information for all NOAA substations for any time
• can read from NEMA AIS receivers and allows you to setup collision alarms.
• can add waypoints to the chart and transmit directions to a NEMA autopilot
• easy switching between different charts at different scales.
• night mode color scheme
• free
• cross platform. Runs the same in Linux, WindowsXP, Vista and OSX.

Some things that it doesn't support which would be nice:

• I don't see a way to save the waypoints, record tracks or any other information
• MOB mode
• anchor alarm
• AIS via internet
• satellite imagery overlays
• support for GRIB overlays
• anti-aliased scaling of the raster charts. They look very bad when zoomed out.
• its supposed to also have support for currents, although the display
• for that is a little screwed up in the current release.
• radar overlays

Still, it is free, which is cheaper than a kick in the teeth. OpenCPN seems to be the only open source chart plotter available -- I expect (hope) it will only be a matter of time before much of this gets implemented. As it is already, it seems pretty capable.

Couple this with a $300 netbook and your boat's got a battle computer.

Update: NOAA's got a new site for downloading charts -- http://www.charts.noaa.gov
Its pretty slick and lets you download packs of charts by state.