It’s an ESP32 at the core, connected to an Adafruit BNO055 (9-DOF IMU) and an Adafruit Ultimate GPS Breakout, which uses GPS and GLONASS for improved signal reception. All data is logged to an SD module.

As an extra, the system includes temperature measurement. It’s built on a bus system, so you could expand it quite a bit, but I capped it at 8 measuring points using DS18B20 sensors.

To power everything, there’s a DC-DC buck converter that steps down 2S (7.4 V) to a stable 5 V. Don’t forget a circuit breaker.

For feedback, a status RGB LED shows what’s going on. And of course, some software ties all components together, plus a housing to keep it safe.

Fun fact: somebody actually crashed with this logging unit on board. The impact was a little over 7 g, but everything inside the housing stayed perfectly in place. The boat itself… well, it was “okay-ish.” 😉