Isochronal Router (ECMWF)

Drag Start & Finish on the map. Paste your polar. Uses ECMWF via Open‑Meteo (no key).

Waypoints

Start lat Start lon Finish lat Finish lon

Format: one "TWA,BSP" per line. Interpolated & assumed symmetric.

Hours Δt (min) Heading step

Minimal demo — no currents/waves/tack‑gybe logic.

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