See How One YouTuber Built an Autonomous, Solar-Powered Kayak Tug Boat
This kayak puller is able to move autonomously to various waypoints while also maintaining a full charge with solar panels.
The idea
Kayaking for long stretches of time can get tiring, so Daniel Riley of the rctestflight YouTube channel wanted to create a tug boat that was strong enough to pull him across the water for impressive distances. But he did not want to stop there, as having to manually control where the tug is headed and making small corrections constantly is also a pain, so he decided to incorporate autonomous navigation too. And finally, the entire thing have the ability to charge with solar panels to give it even more range.
Creating the hull
The base of any boat is the hull, which is the part that sits just below the water level and provides buoyancy to the ship. Riley began the hull for his tug boat by 3D printing a mold and layering many sheets of fiberglass and resin all over it to create a strong foundation. Because a single motor could get quite expensive and still not be powerful enough to pull the required weight, he opted to create a dual-hull boat that would feature nearly identical single hulls bound together with a solid structure.
Adding the propulsion system
Getting everything to move is accomplished by using a pair of brushless DC motors that are normally found in RC planes, but here, their shafts have been replaced with a coupler and connected to a pair of 76mm brass propellers. One nice thing about the shaft configuration is that the entire rod is threaded which means water gets pushed out of the housing as the boat moves forward, and thus helping to prevent leaks. Riley went even further and filled in the space where the drive shaft meets the hull by filling it in with 1 inch of epoxy for some extra security.
Both motors are powered by a set of six 12.8V 10Ah lithium polymer batteries and are driven by a pair of high-capacity ESC modules.
Autonomous navigation
Since this project was created with autonomous navigation in mind, Riley had to first add a GPS mast onto the front of one of the hulls and then wire it into the controller board. Within the ArduPilot software, he was able to set various waypoints on a map and tell the boat to follow them automatically. Even though the boat could only pull his Kayak at around 3 miles per hour, he eventually reached his destination with a surprising amount of battery power remaining.
Keeping the batteries charged with the sun
The final step of creating the autonomous kayak tug boat was keeping the batteries topped-up with a set of solar panels. Once mounted over the hulls, their output was fed into a charge controller that manages charging the batteries with the incoming power from the panels. Overall, Riley considered this project a success, even after running it through some rough waves. He also plans to release a third video in this series where he will embark on a long-distance mission.