The GPS Datalogger

Before even acquiring the ship, I knew I had to have this bit of gizmology; it automates what I did for a couple of years with the maplets of local kayak jaunts aboard Bubba. The unit shown here was made in 2006... but (updated in June 2009) I now have a waterproof GPS Datalogger with Bluetooth for sale in my online store.

In the photo, you can see my simple and expedient packaging job 3 years ago: I just nestled the hardware into a carved foam insert inside a SealLine Electronic Case. The wee antenna is lost in the glare; below that is the board, which carries the Lassen iQ GPS, an LPC2138 ARM processor, and a socket on the back with a 256 megabyte SD card. The software strips the NMEA sentences to just the basics, and stuffs them into the card... which has enough space for 440 hours of logging! I haven't checked the power drain yet, but the four 2300 mAH AA NiMH cells should keep it going for quite a while.

I took this on the first sea trial, bungeed to the propane locker. The LED blinked every second as we played around in the Ship Canal, Lake Union, and Portage Bay. When I got back to the lab, I popped the SD card into my Mac's USB reader, dropped the collected data into a KML template file, and clicked it to launch Google Earth... with utterly wonderful results!

Here is the overall journey, and this is a close-up of our zig-zagging in the Lake to get to know the sails and learn tight maneuvering (the really tight turn in the upper right was done by Chris Tesh as he lectured me on prop walk and engine/rudder tricks; the much sloppier one to the left is mine... looks like I need practice). If you want, you can play with the KML file and your own installation of Google Earth (do a "save link target as" on that, or you'll see a bunch of text in your browser instead).

Ain't technology wonderful? When this site matures a bit, there will be a browsable archive of track logs and related photos.

More added commentary from June 2009: I noticed that this post gets a lot of visitors, so I want to add a bit more information. My GPS Datalogger kit mentioned above is intended to simplify this process, and is based on a Geochron Blue unit from Sparkfun Electronics, packaged in a small Pelican case with a Lithium-Polymer battery and Bluetooth... and is shipped with adhesive-backed velcro so you can leave it attached to a convenient spot on your boat or other vehicle. More detail on the DIY approach is over here, and I'm happy to report that the manual KML-file editing is a thing of the past with the excellent GPS Visualizer (if you use that, please send him some Paypal donation love).