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 is in beta, and feedback from sailors actually using it is what shapes it: what works, what's missing, where it should go next. Try it on your boat, then tell us — open a GitHub issue, or leave an email below and we'll check in now and then. (There's open hardware taking shape too — a pocket GPS pod and a sunlight-readable e-ink chartplotter — and the list hears about that first.)
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