Computes the course to steer to reach a reported position — including the case where that position is itself drifting with wind and current, so the bearing to the last known position is not the course to steer.
Enter the reported position and time; optionally a GRIB file (for wind and surface current) or a hand-entered set and drift; and own-ship position and speed. The plugin ages the position forward to now, solves the moving-target intercept, and shows the course to steer, distance, and ETA, drawing the marks and the course line on the chart.
This software is not verified for operational use. The drift model has
not been reviewed by anyone with search-and-rescue domain expertise — see
docs/LEEWAY_NEEDS_VERIFICATION.md.
It is provided without any warranty (see COPYING, sections 15
and 16). Do not rely on it for navigation or for any life-safety decision.
Not affiliated with or endorsed by the IMO, ICAO, the U.S. Coast Guard, the OpenCPN project, or any search-and-rescue authority.
v0.1.0-alpha — a working plugin with a non-modal input/output panel, datum ageing (GRIB or manual drift), a moving-target intercept solve, and chart marks and a course-to-steer route. Alpha: the drift model is unreviewed and the Windows build has not been run inside a real OpenCPN yet.
Not in the OpenCPN plugin catalogue yet. Download the tarball for your platform from the releases page and import it through Options → Plugins → Import plugin… — full walkthrough with screenshots, and how to remove it, in docs/INSTALLING.md.
Needs OpenCPN 5.8 or newer (see Platform support below).
Requires wxWidgets 3.2, CMake and a C++ compiler.
git submodule update --init --recursive
cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc) --target tarball
Release artifacts come from CI, never a local build — a locally built
library links against your machine's libraries and may not load elsewhere.
For a fast local test you can skip the plugin manager and copy the library
straight in (./scripts/install-local.sh); OpenCPN then treats it as
unmanaged, so there is no Uninstall button — see
docs/INSTALLING.md.
Linux and Windows, built in CI on every push. The Windows build is 32-bit because OpenCPN's official Windows binary is 32-bit; a 64-bit plugin will not load.
The plugin targets plugin API 1.18, so it loads on OpenCPN 5.8 and later.
GPL-3.0-or-later — see COPYING.
Derived from the OpenCPN plugin template by Mike Rossiter and the OpenCPN developers. Bundled and referenced third-party components, and their licences, are listed in THIRD-PARTY.md.