BLE Wind Vane Assembly

ble   blend-micro   anemometer   raspberry-pi   raspberry-pi-zero  

With the main Mr. Gibbs assembly mostly worked out and waterproof, I set my sights on the wind vane this evening.

The mount for the wind vane is intended to clamp on the top of my mast. It is made up of 2 pieces of PVC which are pop riveted together. The Peet Bros anemometer/vane is mounted into the top of the smaller pipe, and a "clean out" plug is glued to the bottom end. The larger section of pipe is the part which will clamp to the mast (with the assistance of a velcro strap) and it has a slot cut into it to give it some give.

The Peet Bros Anemometer is a 4 conductor phone wire, so I thought it would be easy to just use normal RJ connectors to connect it to the blend micro. The tricky part is making this all as waterproof as possible. I made a smaller capsule out of 1" PVC for the "crows nest" board, battery, etc which gets inserted into the bottom of the larger mount.

Inside of this capsule is where the real guts of the operation live. The 4 conductors to the vane go out the top, and the battery (1 18650 cell) go in the bottom.

The PVC enclosure seems pretty ideal in terms of RF interference. In testing I was able to get well over the distance that will be required away and still have a strong data feed. One thing that still remains to be done is to figure out how to make sure everything stays oriented correctly so that heel/pitch measurements won't get shifted around, but I suspect if all else fails a small amount of bubble wrap will do the job.

Lastly, I soldered a new USB plug on to my Pi-Zero. This time I used 30 AWG kynar wire so that the wires wouldn't fray or get shorted out because the shielding had melted, this works out much better than the previous wire I had used.

With everything assembled I was of course anxious to give it all a dry run. I ran into a few software issues which I'm going to detail in another post because it's pretty lengthy.

So what does the wind vane do for me? Quite a bit actually. First, there are 4 new "raw" values available.

  • Apparent Wind Speed
  • Apparent Wind Direction
  • Mast Heel
  • Mast Pitch

By combining Apparent wind with the course over ground and speed from the GPS, we can calculate

  • True Wind Speed
  • True Wind Direction

By combining the heel / pitch values from the Accelerometer in the boat, we can theoretically calculate. (This is really just me experimenting, I don't know if this one will actually work)

  • Mast Bend Port/Starboard
  • Mast Bend Fore/Aft

Lastly, (and perhaps the most exciting one to me) is that I can record maximum boat speed values for each combination of true wind speed + true wind direction, and over time generate polar charts. The system can then refer back to these polars using current values and tell me

  • Nominal Speed (for current wind)
  • Nominal Speed %

That last number is the big one. My ongoing goal has been to distill it down to 3 numbers. VMC % I already have, otherwise known as "am I going the right direction?". With Nominal Speed %, I now have "am I going as fast as I should be?"

I'm also working on a web UI which will allow loading/viewing of the data Mr. Gibbs records. Here's a quick demo of the polar chart in action.

Astute readers will also note a new addition to the pebble fleet, I upgraded my "daily" to the newer time model. It worked just fine with Mr. Gibbs since I had already done the legwork to make it work with firmware 3+


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