| Target Facility | Distance (km) | Distance (NM) | Distance ÷ 14 kts (Not ETA) | Bearing | Buffer Status |
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What does “outside radius” tell you about a ship’s safety?
Only that the rounded spherical distance exceeds your chosen threshold. This page does not calculate threats, charted water depths, legal access, mine locations or vessel restrictions. Use its coordinates and distance arithmetic for geographical comparison, not to choose a voyage route.
Port coordinates, throughput figures and facility descriptions are unsourced fixtures, not live terminal records. Pink connecting lines are authored polylines. A straight connection can cross land or restricted waters; the map and any “distance ÷ speed” figure do not establish a navigable or safe passage.
An illustrative 185 km distance becomes round(185 × 0.539957) = 100 nautical miles. At the fixed assumed speed of 14 knots, the table reports 100 ÷ 14 = 7.1 hours. That excludes routing detours, currents, weather, traffic, port waits and vessel operations. Moving the radius from 180 to 190 km changes this point’s membership, not the physical threat it faces.
The code uses the haversine formula with a spherical Earth radius of 6,371 km and rounds to whole kilometers before converting to whole nautical miles. Initial bearing is also rounded. Points within or equal to the radius pass the threshold; rounding can move a near-boundary point between classes. GeographicLib describes an ellipsoid-based geodesic model, which differs from this simplified sphere. GeographicLib: ellipsoid geodesic documentation
NOAA defines a nautical mile as exactly 1.852 km and a knot as one nautical mile per hour. Those units explain the time division; they do not validate the assumed constant speed or the drawn routes. NOAA: nautical miles and knots
Layer toggles hide or show circles, lines and markers without changing the six destination calculations. JSON radius membership is computed even when the circle is hidden. Reset restores Novorossiysk, 250 km, all layers and the default map view.
IMO provides maritime safety and security material for the Black Sea and Sea of Azov. Its institutional guidance is separate from this user-chosen radius: neither an outside label nor the absence of a colored line certifies safe navigation. IMO: Black Sea maritime safety and security
Distance and speed unit definitions; not transit forecasts.
Comparison with an ellipsoid-based distance model; this page uses a sphere.
Authoritative maritime context; does not validate this radius or port fixtures.