OpenCPN

Review by eFreeware

OpenCPN is a marine chart plotter and navigator for Android, developed by Dave Register and sold for $9.95.

The main reason to consider it is breadth. The app handles several chart formats used in real navigation, accepts GPS data from a range of sources, and layers in AIS tracking, tide prediction and route planning. For someone who wants one screen to plan a passage and follow it, that combination is the appeal.

Built for people who navigate on the water

This is software for boat owners and skippers rather than for casual map browsing. Cruising sailors, racers, fishermen and professional mariners are the kinds of users it targets, and the toolset matches those jobs: charts, routes, waypoints, tides and instrument data on one display.

A tablet mounted at the helm is the obvious home for it, though a phone will run it too. If your boating involves following a line on a screen, watching for traffic and keeping an eye on where the anchor has drifted, the app is built around exactly those tasks.

It also assumes you bring some knowledge with you. Chart formats, NMEA connections and AIS targets are not concepts the app needs to teach from scratch, and the audience it serves already deals in them.

Charts, display modes and downloads

Chart support is the foundation. The app reads BSB v3 raster charts, S57 vector charts with IHO S52-compliant display, and CM93 vector charts with per-cell offset corrections, and it can overlay MBTiles imagery on top. That covers the common formats cruising sailors encounter, including the official vector standard used by hydrographic offices.

A built-in downloader handles getting charts onto the device, and the recent update improved how custom downloader catalogs are managed. You can view a single chart or a quilted mosaic that stitches several together, and switch between north-up, course-up and chart-up orientation depending on whether you want the world fixed or the boat pointing up the screen. A moving-map mode is there as well.

Annotation is handled through GPX layers, which let you draw notes and marks over a chart, and a set of display themes lets you adjust the look for different light conditions. There are also links out to Google Maps and an eBook user manual bundled in for reference.

Position, traffic and safety tools

GPS input is unusually flexible. The app can use the device's own receiver, a Bluetooth GPS, a networked source over TCP or UDP, or a standard NMEA 0183 feed, and it includes a multiplexer for handling NMEA message streams. Autopilot output is supported, so a route followed on screen can be sent to compatible steering gear.

AIS is where the safety side lives. The app accepts networked AIS input and tracks targets with collision alerting, which is the feature that turns a chart display into a watch-keeping aid in busy water. It also handles SART signals with a selectable MMSI for automatic man-overboard handling, and supports DSC and GPSGate Buddies.

For time at anchor, there is an anchor watch with an alarm, and tide and current predictions can be displayed by location. Route planning incorporates tidal data, and the app includes built-in great-circle routing for longer passages. Waypoint navigation and route navigation with ship tracking round out the passage tools.

Waypoints, tracks and routes move in and out through GPX files, so plans made elsewhere can be brought in and logs taken out. The most recent update added a new GRIB weather source, Harmonie from the Netherlands, and improved the import and export file dialog.

What it costs and what that buys

OpenCPN is a one-time purchase of $9.95. There are no ads, and there are no in-app purchases, so nothing inside the app is gated behind an additional payment. You pay once and use the charting tools the app ships with.

Charts themselves are a separate matter from the app's price, and the downloader exists to help you source them. The paid model stands out against subscription charting services, where access is rented month by month; here the cost is settled at the outset. The trade-off is that the app's polish and support come from a small development effort.

How it compares with the alternatives

The main alternatives fall into two groups. Dedicated marine chart plotters from hardware manufacturers bundle charts and support, and subscription-based charting apps charge ongoing fees for current data. OpenCPN sits apart from both: a paid app that reads multiple chart formats and expects you to supply the charts.

If your needs stop at knowing roughly where you are, simpler tools will do the job; the reason to pay for OpenCPN is the depth of the marine-specific toolset.

With more than 10,000 installs, it has an established user base.

A considered purchase for serious small-craft navigation

OpenCPN is worth the $9.95 for boat owners who want desktop-grade charting on an Android device and are comfortable working with chart formats, NMEA connections and AIS. The combination of raster and vector chart support, flexible GPS input, collision alerting and tidal route planning is a lot of capability for a single payment, and the continuing updates suggest the project is active.

It is a less obvious fit for the casual user who wants a simple map on the water. The feature set is deep, the terminology is technical, and the rating is middling. Approach it as a tool for people who already know what a quilted chart display and an NMEA multiplexer are, and it makes sense.

For cruising, racing, fishing or professional work where charts, traffic and tides all matter, this is a serious option to weigh against subscription services and vendor-locked plotters. Buy it for the capability, not for hand-holding.

What's new in version 5.14.0

Add new GRIB source: Harmonie(nl) Improved UX for import/export file selector dialog. Improved UX for custom chart downloader catalogs.