I've spent the day indulging my inner geek, and bemoaning the lack of an inner craftsman!

Those of you who've clicked on any of the "log of this passage" links, or tried the "time-lapse" link bottom right, may wonder how that data is collected.

I have on board a Raspberry Pi single board computer. This is a tiny little computer that on its own costs about £36. This has a small GPS receiver plugged into it, and logs my position continuously to upload to the logging service. It also has an interface to the on board navigation network (NMEA2000 or N2K in the jargon) allowing it to also collect wind speed and direction, depth, water speed, etc. Finally, it also connects to a small WiFi router on board, which allows me to access all this data from my iPad or iPhone. It's quite fun when filling with water to be able to look at my phone to see how full the tank is!

So if all this is working, what have I been up to today?

Well, the current set up has a couple of problems. The power supply to the Raspberry Pi is problematic: it needs 5V, the boat is 12V, and the various devices I've tried seemed unreliable. Further, Pis don't like being turned off at the power supply - it can corrupt their files - so you're supposed to do a proper shutdown before turning off the power. The second main problem is the interface to the N2K navigation network. I'm using a device from Actisense. It's OK, but some bugs have emerged recently with it, and it can only be configured from a Windows PC, which I don't have on board. So even if they release a bug fix, I can't implement it.

I recently came across an add-on board (in the jargon, a "hat") for the Raspberry Pi that solves these problems. The Sailor Hat can take input power anywhere from 5-24V, and transform it for the Pi. It has a large on board capacitor, so it can detect the input voltage has been turned off and tell the Pi to shutdown gracefully, powering it from the capacitor for long enough to let it do so. And it has an onboard interface to the N2K network, controlled and configured from within the Raspberry Pi.

I had the kit delivered to my sister, and picked it up from her in Newcastle - thanks lil sis! Today I assembled it. That required soldering the power supply and interface cables to the panel plugs, and drilling holes in the box for the panel plugs. Wow! Even with my reading glasses on, my arms aren't long enough to easily solder such tiny wires. Doing it with a gas powered soldering iron didn't help! In the end, I got it done, and the kit assembled. Then I downloaded and configured the software.

One problem: I don't have an NMEA2000 cable long enough to plug it in! I'd forgotten that the existing interface has an integral cable. So I can't complete the upgrade until I find a chandlery that stocks N2K cables ... and in these parts that could be quite a long time. Oh well, I had fun doing the work (once the soldering was done...).

Tomorrow it's an early start at 6am to get the tide round Rattray Head en route to Lossiemouth.

PS I also fitted the replacement sail slide, duly sent to me by Elvstrom Sails in Hamble. Thanks guys!