Using Boat Instruments and Video to Enhance Sailing Practice Sessions

I recently found a way to incorporate our boat data to videos we shoot. The basic principles are:

- Collect all NEMA messages
- Take a video
- Synchronize the two and create nice gauges

This process is pretty much straight forward, however I faced a couple of issues in the process:

- The synchronization is not always evident, I used our tacks and distance between the tacks in order to find how to synchronize the video.
A better approach would be to film a watch and thus "time-stamp" the video so I can use the NMEA GPS timestamp to then find a sync point.

- The NMEA data understood by most software are GPS ONLY, this is not what I want. I want to have our wind instruments measurements, I want to have our speed over water values and I want to have our upwind and downwind optimal VMG targets.

The first piece of software I created was to take as an input NMEA data and create a CSV file. NMEA information comes at irregular interval, sometimes data is missing and needs to be linearly interpolated.

Now I wanted to have the optimal targets on it, so I have to include them using the velocity prediction calculated for our boats:

Once you have that the remaining action is to synchronize the data with the video, and create overlays

At the end you have a very sweet video that you can use to review your practices, see when you're fast, when you're slow, and what can be improved. Et Voila!

And the youtube video: