There’s a thriving ecosystem of free nautical charts online, completely legal to use, that can keep your navigation sharp and your budget intact. Think of these as professional-grade resources made accessible for free, often updated by hydrographic offices themselves. Here’s a deep dive into the most useful sources, how to get the charts onto your system, and why they’re worth adding to your navigation toolkit.
Quick reminder:
Raster charts (RNCs) are great for those who want paper-chart familiarity;
Vector charts (ENCs) are scalable, customisable, and more adapted to digital navigation softwares.
Online chart viewers are web apps that require an internet connection. Click here if that’s what you’re looking for.
OpenCPN Chart Downloader Plugin
Instead of hunting for chart providers one-by-one, you can use OpenCPN’s built-in chart downloader plugin. It connects directly to NOAA, OpenSeaMap, and other providers.
Steps:
- Install OpenCPN (Windows, macOS, Linux).
- Open the chart downloader plugin under Options.
- Select a catalog (e.g., NOAA ENCs).
- Choose regions and download in bulk.
- Refresh the chart database.
This keeps your charts updated with minimal effort.
Free government-issued charts for download
Formats:
– RNCs are in BSB/KAP format—bitmap images georeferenced for navigation.
– ENCs are in S-57 format—the international vector chart standard.
Installation:
– OpenCPN: Drag-and-drop the chart folder into OpenCPN’s chart directory. Update the database and you’re live.
– QtVlm: Same process—select the ENC/RNC directory in chart settings.
- USA: The National Oceanic and Atmospheric Administration provides free access to both Raster Navigational Charts (RNCs) and Electronic Navigational Charts (ENCs). The US Army Corps of Engineers provides Official Inland Electronic Navigation Charts (IENC) of U.S. inland waterways.
- New Zealand: NZ ENC are official vector Charts published by the New Zealand Hydrographic Authority (NZHA) providing coverage of New Zealand territory waters. LINZ charts are free and high-quality, both in raster and ENC.
- Brazil: Diretoria de Hidrografia da Marinha (DHN) and the Centro de Hidrografia da Marinha (CHM) provides downloadable chart packs in both ENCs and RNCs formats.
- Norway: Kartverket releases raster charts on a free online chart viewer.
- South China Sea region: The East Asia Hydrographic Commission (EAHC) produces small scale official Electronic Navigational Charts (ENC) of the South China Sea to serve the maritime community. The EAHC has ten Member States (MSs) : Brunei Darussalam, China, Democratic People’s Republic of Korea, Indonesia, Japan, Malaysia, Philippines, Republic of Korea, Singapore and Thailand.
- Peru: The Departamento de Hidrografía (DIHIDRONAV) provides free raster charts download.
- Inland European Waterways: Austria, Belgium, Bulgaria, Croatia, Czech Republic, France, Germany, Hungary, Luxembourg, Netherlands, Romania, Serbia, and Slovakia charts for inland navigation are all provided by the River Information Services (RIS) in vector format for download at eurisportal.eu. Alternatively you can download the tiles you need on this chart selector.
+ Poland
+ Switzerland
Navionics, Garmin, and ActiveCaptain
Navionics has long been a household name in recreational charting, but its model has changed. On October 27, 2017, Navionics was acquired by Garmin Ltd. At the end of 2023, Navionics® Boating decommissioned its online chart viewer, removing a useful free planning tool that many sailors relied on. Access to previously purchased charts now requires an active subscription through the Navionics app.
However, a simpler, less detailed, chart viewer is now available in Garmin’s ActiveCaptain platform. While it doesn’t offer the full depth and polish of the former Navionics web viewer, it provides enough coverage for route planning and waypoint management. Just select Nautical in chart settings.
Link: Garmin ActiveCaptain
OpenSeaMap
Think of OpenSeaMap as the marine equivalent of OpenStreetMap. Volunteers and mariners continuously update features: buoys, ports, anchorages, marinas, depth contours. The data isn’t intended to replace official hydrographic charts, but it’s invaluable for adding context and cruising information.
Link: OpenSeaMap
Offline charts can be extracted as tiles for OpenCPN via the chart downloader plugin.
An open-source chartplotter on a Raspberry Pi
Most commercial chartplotters (Raymarine, Garmin, Simrad) are locked to proprietary chart packs. For free solutions, a Raspberry Pi running OpenCPN, connected to NMEA data, offers an open-source chartplotter alternative.
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