In June 2022, I built a proof of concept free-floating ocean research buoy. The primary objective of the buoy is to measure ocean currents as it floats around. The buoy uses GSM cellular for data transmission so another purpose of this design is to determine if it is viable to omit satellite modems often used on other similar projects.
The buoy is ESP32-based and features GPS, temperature sensors, a light sensor, a 9dof IMU for motion sensing, a SIM800L GSM modem, an ESP32-CAM with a fisheye lens, and a 32GB high-endurance SD card. The electronics are housed in an IP68 junction box with 800g of clay to lower the center of buoyancy. The PCB is screwed into wood which is sealed into the enclosure using silicone.
For power, an 18650 3500mAH battery is recharged by a 3W solar panel using an Adafruit “Universal USB / DC / Solar Lithium Ion/Polymer charger - bq24074”. I am using buck/boost converters to provide 3.3v to the sensors and ESP32s. Transistors cut power to hardware which is not in active use to save power.
On the evening of June 16th 2022, I launched the buoy on the beach in Blackpool, England. The buoy reached a maximum distance of 6.45KM (3.48NM) from land and then was washed ashore again on the afternoon of the following day.
The following images were captured by the buoy camera during the journey:
(click an image to enlarge)
On the morning of June 25th 2022, I attempted to launch the buoy on the beach in high winds. Unfortunately, the wind did not take the buoy out to sea as I hoped. Instead, the large waves caused by the wind threw the buoy against rocks multiple times causing significant damage.
No water entered the enclosure however I felt the integrity was compromised so I eventually retrieved it from the water and took it home.
This photo was captured during a point where the buoy was submerged by a big wave: