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Enter two positions in either decimal degrees (36.45) or degrees / minutes (36 27.0 N / 014 30.0 E). The calculator returns:
Spherical Earth assumed (mean radius 3440 NM / 6371 km). Vincenty's ellipsoidal formula gives slightly more accurate results on long passages but the spherical figure is normally within 0.5%. For voyage planning, always cross-check against the ship's ECDIS / passage plan.
Enter two positions to compute.
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Scenario:Voyage Yokohama (35°26.6'N, 139°38.7'E) → Long Beach (33°45.6'N, 118°11.6'W). Vessel service speed 14.5 kn.
Great-circle: ~4,470 NM · initial course ~068° · passage time ~13 days.
Rhumb-line: ~5,220 NM · constant course ~091° · passage time ~15 days.
Interpretation: Great-circle saves ~750 NM (~2 days), but bulges to ~50°N and may add weather + parametric-roll risk in winter — weather-router will likely recommend a composite route splitting the difference.