💻 Open Source & DIY Marine Technology
Free, community-built alternatives to expensive proprietary marine electronics. A Raspberry Pi, a $35 HAT board, and open source software can replace thousands of dollars of black-box hardware — and you'll understand every bit of it.
📡 Signal K — The Open Marine Data Standard
Signal K is the backbone of the modern open source marine stack — everything else in this guide connects to it. Think of it as the USB hub for your boat's data: it takes every instrument, sensor, and device on your boat and makes their data available to every other device over WiFi using simple web technologies.
SignalK.org — The Hub
Free, open data platform that connects all your boat's instruments, sensors, and devices over WiFi using JSON over WebSocket. The standard that everything else builds on.
signalk.org →Signal K Server (GitHub)
Runs on a Raspberry Pi. Aggregates NMEA 0183, NMEA 2000, and Seatalk data into one universal feed accessible by any device on your boat's network.
github.com/SignalK →WilhelmSK — iOS Dashboard
Highly customizable boat instrument dashboard. Reads live Signal K data over WiFi and displays speed, depth, wind, engine data, AIS, and more on iPhone, iPad, or Apple Watch. Developed by Scott Bender. Fully integrates with iOS Shortcuts.
App Store (iPhone/iPad) →Support Signal K
Volunteer-run project. Donations keep the development active and the servers running. If this software is on your boat, consider contributing.
opencollective.com/signalk →🖥️ Software — Chartplotters, Autopilot & Navigation
OpenCPN — Free Chartplotter
Free, open source chartplotter and navigation software. Runs on Windows, Mac, Linux, Android, and Raspberry Pi. GPS/GNSS position, BSB raster charts, S-57 vector ENCs, AIS decoding, waypoint navigation, anchor alarm, autopilot output, GRIB weather, tide/current prediction, 45+ plugins.
opencpn.org →OpenPlotter — Marine OS for Raspberry Pi
A complete marine-optimized Linux OS for Raspberry Pi. Pre-installs OpenCPN, Signal K, PyPilot, MAIANA AIS, and a WiFi access point in one ready-to-flash image. A $35–$80 Raspberry Pi running OpenPlotter replaces a dedicated chartplotter, AIS receiver, instrument hub, weather display, and anchor alarm simultaneously.
openmarine.net →Bareboat Necessities (BBN Marine OS)
Alternative open source marine Linux for Raspberry Pi. Signal K, PyPilot, OpenCPN, and AvNav preconfigured in one image. Excellent documentation. Aimed at offshore sailors who want a complete, reliable system without vendor lock-in. Works well on a dedicated Android tablet as a helm display.
bareboat-necessities.github.io →PyPilot — Open Source Autopilot
Free, open source autopilot software and hardware by Sean D'Epagnier. Raspberry Pi-based; works with tiller and wheel steering on boats up to ~40 ft. Features: automatic sensor calibration, compass/GPS/wind steering modes, Signal K and NMEA 0183 integration, OpenCPN plugin, very low power draw. The TinyPilot is a WiFi-enabled mini controller (Raspberry Pi Zero) — a complete autopilot computer smaller than a deck of cards.
pypilot.org →🛠️ Hardware Projects — AIS, NMEA & More
MAIANA — Open Source Class B AIS Transponder
The first fully open source Class B AIS transponder. Hardware designs, firmware, and manuals are all free. Self-contained unit with AIS and GNSS circuits in the antenna housing. Outputs 2W (+33dBm); verified 20+ nm range from masthead, 10+ nm from pushpit. Runs on 12V; outputs NMEA 0183 continuously. Integrates directly with OpenPlotter and Signal K. A commercial Class B AIS transponder costs $350–$600. A MAIANA kit costs a fraction of that.
github.com/peterantypas/maiana →CANboat — NMEA 2000 Tools
Open source NMEA 2000 PGN decoder and utilities. Reads and writes N2K messages — essential for troubleshooting NMEA 2000 networks and connecting your N2K backbone to Signal K.
github.com/canboat →kplex — NMEA 0183 Multiplexer
Open source NMEA 0183 multiplexer for Linux/Mac. Routes data between serial, TCP, and UDP sources — sentence filtering and failover built in. Connects multiple NMEA 0183 devices to Signal K cleanly.
github.com/stripydog/kplex →OpenSkipper & vYacht
OpenSkipper — display and process NMEA 0183, NMEA 2000, and AIS data; Windows-based instrument display. vYacht — open source wireless boat network hardware and software; WiFi NMEA bridge for connecting older instruments to modern systems.
openskipper.org →Hardware & Community Resources
- Open Boat Projects — curated catalog of open source marine hardware and software projects; great starting point for what's available
- Copperhill Tech — RPi Marine Hub Guide — step-by-step guide; also sells the PICAN-M HAT (NMEA 0183 + NMEA 2000 interface board)
- SeaBits — NMEA 2000 powered Raspberry Pi; wiring guides and real boat builds
- Hackaday — Marine Projects — open hardware marine builds from the maker community
- Reddit r/sailing — Signal K discussions
- Sailing Anarchy — Open Source Marine Linux thread — real-world sailor experiences with RPi builds
- OpenMarine Shop — buy pre-assembled PyPilot hardware and MAIANA kits if you don't want to source components yourself
🛒 Recommended Hardware Shopping List
Everything below is a real part with a confirmed supplier. Prices approximate as of 2026 — verify before ordering.
The Brain — Raspberry Pi
| Part | Price | Notes |
|---|---|---|
| Raspberry Pi 4 — 4GB | ~$55 | Sweet spot for OpenPlotter. Handles chartplotter, Signal K, AIS, and autopilot simultaneously. Buy from CanaKit, Adafruit, or PiShop.us |
| Raspberry Pi 5 — 4GB or 8GB | ~$60–$80 | Faster; supports NVMe SSD (more reliable long-term). Best for OpenPlotter 4.x. Recommended if adding an SSD. |
Marine Interface HATs — Pick One
| Part | Price | Notes |
|---|---|---|
| PICAN-M HAT — Copperhill | ~$99 | NMEA 0183 (RS-422) + NMEA 2000 (Micro-C) + 3A onboard power supply. Runs Pi directly from 12V ship power. Plug-and-play with OpenPlotter and Signal K. |
| MacArthur HAT — OpenMarine | ~$120–$150 | More modular. NMEA 2000, 2× NMEA 0183 in/out, smart power management, Seatalk1, Qwiic sensor connector. Buy only the modules you need. Also at Wegmatt. |
Storage
| Part | Price | Notes |
|---|---|---|
| microSD — 32GB or 64GB, Class 10 / A2 | ~$10–$15 | Samsung Endurance Pro or SanDisk Endurance series. Standard cards wear out from constant writes a marine server generates. |
| NVMe SSD (Pi 5 only) | ~$35 | With the official Raspberry Pi NVMe Base, a 256GB SSD replaces the microSD entirely. Much longer lifespan on a boat. |
GPS
| Part | Price | Notes |
|---|---|---|
| GlobalSat BU-353-N USB GPS | ~$40 | Waterproof, 75-channel, uBlox chipset, 6 ft cable, magnetic mount. Plug into Pi's USB port. Works out of the box with OpenCPN and Signal K. |
| VK-172 USB GPS dongle | ~$10 | Budget option. Works fine for testing and fair-weather use. Not waterproof. |
Display
| Part | Price | Notes |
|---|---|---|
| 10" HDMI touchscreen | ~$60–$80 | Mounts well at nav station. Search "Raspberry Pi 10 inch HDMI touchscreen" on Amazon. |
| Existing laptop or tablet | $0 | Signal K serves a web dashboard to any device on your WiFi network. You may not need a dedicated screen at all. |
Power & Enclosure
| Part | Price | Notes |
|---|---|---|
| 12V to 5V DC-DC converter | ~$12–$20 | Only needed if your HAT doesn't include onboard power regulation. Look for models with reverse polarity and overvoltage protection. |
| IP65 project box | ~$15–$25 | For exposed installs. Use PG7 waterproof cable glands. Search "IP65 project box Raspberry Pi" on Amazon. Below-deck in a dry locker: any plastic project box works. |
| Blue Sea fuse block | ~$20 | Always fuse the Pi's power feed at 3A. Never run it unfused off ship's power. |
💰 Total Estimated Build Cost
🔨 What You Can Build for Under $200
- ✅ Full chartplotter with AIS overlay and weather routing (Raspberry Pi 4 + OpenPlotter + OpenCPN)
- ✅ Boat-wide instrument network accessible from phone or tablet via WiFi (Signal K server)
- ✅ Tiller autopilot with wind vane and GPS steering modes (PyPilot)
- ✅ Class B AIS transponder — transmit and receive (MAIANA)
- ✅ NMEA 0183 / NMEA 2000 bridge connecting old and new instruments (CANboat + kplex)
- ✅ Anchor alarm, tide predictions, GRIB weather on any phone or tablet (OpenCPN + Signal K)
🎥 YouTube Channels & Tutorial Guides
YouTube Channels
- Après Sail — the best multi-part series on building a complete DIY marine electronics system: OpenPlotter, Raspberry Pi, Signal K, and OpenCPN from scratch on a real boat. Start here.
- raspberry4sailing — tutorials specifically for Raspberry Pi marine projects: Node-RED, sensors, instrument displays, Signal K integrations on a sailboat
- The Low Cost Sailor — DIY marine electronics, OpenPlotter builds, low-budget chartplotter builds, practical how-to videos
Key Tutorial Articles
- Copperhill Tech — Comprehensive OpenPlotter & Signal K Guide — written walkthrough from hardware selection through full installation
- OpenPlotter Official Docs — Getting Started — download, flash, first boot
- SeaBits — NMEA 2000 Powered RPi — power the Pi directly from your NMEA 2000 backbone; clean wiring guide
- The Low Cost Sailor — Budget Chartplotter Build — full parts list and setup guide
- Understanding OpenPlotter / OpenCPN / Signal K — clear conceptual explanation of how the three systems relate before you start building