Quiet electric trolling motors are great for gliding through your favorite fishing spot, but require constant correction if wind and water currents are involved. As an alternative to expensive commercial GPS guided trolling motors, [AlexAsplund] created Vanchor, an open source system for adding an autopilot to a cheap trolling motor.
To autonomously control a commercial trolling motor, [Alex] designed a 3D printed stepper motor powered steering unit to be attached to the original transom bracket on the vertical motor shaft. A clamp screwed onto the shaft locks the motor in the steering unit when the motor is lowered. The main controller is a Raspberry Pi, which hosts a WiFi hotspot and a web server for control and configuration using a smartphone. Using navigation data from an electronic compass sensor and marine GPS chartplotter, it can maintain its position, move in a specified direction, or follow a set route. [Alex] is also considering adding the ability to use a GPS module instead of a commercial plotter.
For an estimated total of $ 300, including the motor, this appears to be a viable alternative to commercial systems. Of course, it might be possible to add even more functionality by integrating the open source ArduRover autopilot, as we have seen. [rctestflight] do on several autonomous ships. You can also build your own open source chart plotter using OpenCPN, which rivals commercial offerings.