Concept

Territorial sea — where it appears

The belt of sea up to twelve nautical miles wide over which a coastal state is sovereign. Its outer limit is the line every point of which is the breadth of the belt from the nearest point of the baseline, which is the envelope of arcs drawn about the low-water line or the straight lines replacing it.

Named by 2 essays across one field — each of them below, with the objects they name alongside it.

Two lawful systems, one sea: the lines move water between regimes and the outer limit does not move. The stated archipelago with the lawful system enclosing the most water (solid, 186,617 km² inside) and the one enclosing the least (dashed, 159,032 km²). Round each, the limit two hundred nautical miles from its baselines and from every island's coast: the two outer limits lie on top of each other everywhere but a few kilometres off the widest gaps. A straight coast stands 700 km east of the centre; the line equidistant between it and the archipelago is drawn for both systems and they coincide. Inside plus outside, the two systems account for 1,344,857 km² and 1,343,864 km² of sea.

The archipelago rule moves water between regimes, not between states

The eighteen baseline systems the archipelago article allows on a stated archipelago differ by 27,585 square kilometres of water inside the lines. Measured outward, as the Convention measures every zone, the difference almost vanishes: whatever a system takes inside it gives up from the zone outside, and water inside plus zone outside differs by 993 square kilometres, seven hundredths of a per cent. Against a straight neighbouring coast on any side, the equidistance line does not move at all, because a baseline's nearest point to a straight coast is always an island. Only a neighbour facing the middle of a gap feels the choice — 2,112 square kilometres at thirty kilometres off, 688 at 250.

practice · Boundary

The coast copied twelve miles out gives up the sea of every narrow bay. A stated coast 116 km long with five bays 5 km deep, 6, 10, 16, 24, 36 km wide. Dashed: the envelope of arcs, the line every point of which is twelve nautical miles from the nearest point of the coast. Solid: the coast itself moved twelve miles seaward, which dents the limit by the full 5 km over every bay. Tinted: the sea between them, 240 km² in all, 9% of a straight coast's territorial sea. Over the 6 km bay the copy lies 4.8 km inside the envelope; over the 36 km bay the two meet. The coast is stated, not surveyed.

Copied out to sea, a coast keeps its length and loses its bays

Before 1930 a territorial sea was drawn by following the coast in all its sinuosities, and the phrase fits two constructions. Moved twelve miles seaward, a stated coast of five bays gives up 240 square kilometres against the envelope of arcs, most of it over the narrowest bay; moved along its own normals, it ties a loop over every bay. On a fractal coast charted at finer detail the copy grows by a quarter at every level, to 480 kilometres, while the envelope settles at 133.0.

practice · Boundary

Named alongside it

The objects these essays reach for when they reach for this one.

Baseline Boundary Verification Buffer Convention Equidistance Fractal dimension Radius of curvature Raster Resolution Tolerance

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