Open Source Solutions for Station-Keeping, Navigation & Security
Role: Main autopilot controller
PyPilot is exceptionally well-suited for your application because it's designed for small vessels and supports custom motor controllers via Python. Your differential thrust setup requires modifying the motor driver to output skid-steering commands.
Modifications Required for Differential Thrust:
arduino_servo or pypilot_motor controllermix_thrust(rudder, throttle) function:
left_thrust = throttle - (rudder * throttle_factor) right_thrust = throttle + (rudder * throttle_factor)
Pros: Lightweight, runs on Raspberry Pi Zero 2W, weather vane mode for power saving
Cons: Will require custom PID tuning for high-drag platform
Role: Universal marine data exchange standard
Modern maritime software "language" that connects all your systems. Converts NMEA 0183/2000 from sensors into JSON for web apps.
Critical for your build:
More robust than PyPilot for complex missions but heavier resource usage. Native support for skid steering (differential thrust) without code modifications.
Configuration for your vessel:
FRAME_CLASS = 2 (Boat)
FRAME_TYPE = 0 (Skid Steering)
SERVO1_FUNCTION = 73 (Throttle Left)
SERVO3_FUNCTION = 74 (Throttle Right)
PILOT_STEER_TYPE = 1 (Separate steering/throttle)
ATC_STR_RAT_MAX (yaw rate max) values due to cable constraints limiting turning speed.
The standard for electronic chart display. Essential for route planning and monitoring position.
Plugins needed:
Best for marine security: Uses AI (TensorFlow Lite) to distinguish between waves, birds, and actual threats (boats, people, debris).
Advantages for seasteads:
Mature, feature-rich, but heavier resource usage. Good if you have computing power to spare.
Setup recommendation: Run on separate Raspberry Pi 4 from navigation system to avoid GPS lag during motion detection processing.
Simple web interface for motion-triggered recording. Suitable for basic "is someone on deck" monitoring without AI features.
| Function | Hardware | Software Stack | Power Budget |
|---|---|---|---|
| Primary Navigation | Raspberry Pi 4 (4GB) | PyPilot + Signal K + OpenCPN | ~7W |
| Security/Monitoring | Raspberry Pi 4 (4GB) separate unit | Frigate NVR + Coral TPU | ~10W (15W with TPU) |
| Sensor Hub | Arduino Mega or ESP32 | Custom firmware for column strain gauges | ~2W |
| Power Management | Victron Energy Cerbo GX (or RPi with hat) | Venus OS (Linux-based) | ~3W |
Your 4-point cable system (44'×68') creates a restricted turning envelope. The software must know that:
Solution: Implement a "virtual rudder" limit in software—restrict heading changes >15° unless vessel is stationary.
At 1 MPH with 2.5m propellers against ocean currents, your motors may draw 2-4kW combined. With solar-only power, you have approximately 2-4 hours of runtime per day assuming 8kW of panels.
Software must include drift mode: Calculate if maintaining position is possible with available battery/solar, or if you must drift with currents.
For a 30,000 lb platform with high windage, standard PID controllers will oscillate. Consider implementing:
| Phase | Tasks | Key Software |
|---|---|---|
| Phase 1: Basic Control |
Manual joystick control, differential thrust mixing | Arduino motor controller + PyPilot |
| Phase 2: Automation |
GPS hold, basic station-keeping | PyPilot + Signal K + GPS/IMU |
| Phase 3: Integration |
Chart plotting, route following | OpenCPN integration |
| Phase 4: Security |
Camera monitoring, perimeter alerts | Frigate NVR |
| Phase 5: Intelligence |
Collision avoidance, weather routing | Node-RED + weather APIs |
pypilot/pypilot - Sean D'Epagnier's autopilot (active development)SignalK/signalk-server - Marine data universal translatorblakeblackshear/frigate - AI surveillance (excellent documentation)ArduPilot/ardupilot - If you need mission-planning capabilitiesFor your specific seastead:
This stack will run on approximately 25-30W of computing power—manageable for a solar seastead while providing commercial-vessel capabilities.
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