The first Maker Boat Advanced ever built required a stabilized, downward-looking GoPro Hero5 Black camera. To accommodate the GoPro and a 3-axis gimbal the electronics are housed in a 160 mm diameter acrylic tube that terminates in a dome port. A separate, waterproof box keeps the batteries dry. Obviously, a more traditional build would probably use some type of waterproof box, or perhaps the hulls themselves, to house the autopilot and batteries. However, in this case, a gimbal-stabilized, real-time underwater video link required a direct connection between the camera and the other components.
Electronics Tray
The electronics tray consists of 3D-printed disks, aluminum profiles, and an aluminum sheet. Two M3 threaded rods keep it from rotating inside the tube. Given the number of components that require electricity, power distribution takes up one side of the electronics tray.
The power distribution side of the the electronics tray uses a terminal strip to distribute power to each component. A Holybro PM07 powers the Pixhawk 4. The Blue Robotics Basic ESCs connect directly to the terminal strip. The battery cable and the thruster cables enter the enclosure via IP68 cable glands. Bulkhead connectors would make opening and closing the enclosure easier, but they increase the price considerably.
Herelink
On the opposite side of the electronics tray, a Mauch power supply connects to a Herelink air unit. The Herelink air unit sits underneath two cooling fans. Read more about the Herelink air unit installation here.
Gimbal-Stabilized GoPro
A Tarot 3-axis gimbal, mounted at the bottom of the electronics tray, stabilizes the GoPro Hero5 Black. The gimbal stabilizes the camera in choppy seas, but it cannot correct for the heave of the vessel. The HDMI ribbon cable connects the GoPro to the Herelink air unit, providing a real-time video link to the ground control unit.
Powering the GoPro
A 4-pin JST connector on the gimbal arm provides 5V to the GoPro via the USB-C port next to the HDMI out. Will over at Flying Tech sorted us out with a 4-pin JST connector and a low-profile USB-C cable with bare leads. Note that this solution keeps the GoPro powered while in use. When starting with a completely dead battery, unplug and remove the camera from the gimbal and use a wall charger.
Pixhawk 4
The Pixhawk 4 finds a home on a 3D-printed disk near the top of the electronics tray. Unlike most of the other components, the Pixhawk 4 is mounted horizontally. Cable lengths largely determined the final location of the Pixhawk 4. The Herelink antennae are mounted above, and on either side of, the Pixhawk 4. When the Maker Boat Advanced floats on the water, the antennae sit approximately 30-40 cm above the surface. At this height, video and data can be transmitted to the ground unit over distances greater than 100 m.
