Open-source marine chartplotter · beta
Pelorus Nav is a free chartplotter for the browser and Android and iOS, and beyond: official NOAA vector charts with standard modern symbology, offline tide and current predictions, and no account needed. It's young — in beta, improving steadily, and built in the open by a sailor.
Runs in any modern browser — nothing to install, no account needed. iOS is in the works; sign up to join the testing program.
Not for navigation: please treat it as a planning and situational-awareness aid, and carry official charts.
Under way in Boston Harbor — NOAA ENC data with IHO S-52 symbology, live instruments, street basemap blended in near shore.
A quick tour — official charts, routes and waypoints, tides and currents, track review, and the crew-overboard button.
Official NOAA electronic navigational charts — the same public ENC data behind commercial plotters — rendered with standard marine symbology, on hardware you already own.
Vector ENC coverage of all US waters — depths, buoys, hazards, and lights with their real characteristics — drawn with standard S-52 marine symbology. You can import your own charts in various formats as well.
Download a region once and charts, tides, and place search keep working without a signal. Saves battery and works anywhere.
Predictions computed on-device from NOAA harmonic stations; thousands of tide and current stations.
Routes, waypoints, track recording, course projection, and crew-overboard button.
The device's own GPS works out of the box, and Bluetooth GPS pods pair in a couple of taps. Signal K and NMEA connections are implemented too, though early and still only lightly tested.
Marine display themes for real conditions, including one tuned for sunlight-readable e-ink tablets.
Day-sailors, club racers, charterers, dinghy cruisers — if your "chartplotter" is the phone in your pocket, this is for you.
Pelorus Nav is MIT-licensed and developed in public — the code, the chart pipeline, the roadmap, the mistakes. You can read it, file issues, build your own, or self-host the whole thing.
Being open source is also a promise of continuity: the code and the free charts will be there for good, whatever comes next for the project.
Pelorus Nav is conceived and built by a professional software engineer with 45 years of experience in high performance graphics software, Gary Oberbrunner. I strongly believe in creating the highest quality code and a beautiful user experience, so all the code is thoroughly tested end to end, and code-reviewed frequently to reduce errors and ensure security.
Pelorus Nav iOS and Android apps are in closed beta, and feedback from sailors actually using it is what shapes it: what works, what's missing, where it should go next. Leave us an email below if you're interested in testing and we'll get you on the beta for iOS or Android. Try it on your boat, then tell us — open a GitHub issue. (There's open hardware taking shape too — a sunlight-readable e-ink chartplotter — and the list hears about that first.)
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