Fable
The lightship fleet with no central tower
The bay originally had one central lighthouse, and all ships entered the port according to its light signals. On clear days, this method was simple and reliable. Later the sea fog thickened, and a new pier was built near the reefs. The central lighthouse couldn't see every patch of water, and distant small boats were already off course by the time they received orders. The harbor master first raised the central lighthouse higher. The light shone farther, but was still blocked by fog; and if the central tower stopped, the whole bay fell into chaos.
He also required all small boats to keep reporting to the main tower. The reports became so numerous that the signals clogged, and truly dangerous distress calls were drowned out.
The old captain proposed that ships should also be able to send short light signals to each other: position, heading, danger, yielding intent. Each ship judges nearby conditions according to common harbor rules.
At first the captains were not used to it and worried that things would fall apart without a central order. In one heavy fog, three fishing boats confirmed light signals with one another by the reef, automatically formed a line, and went around; by the time the central lighthouse order arrived, the danger had already been avoided.
The harbor official still kept the harbor rules and after-the-fact records, but no longer tried to approve every turn of the rudder. No ship knew the whole bay, but each ship could reach small-scale agreement with nearby ships.
The harbor official worried that mutual light signals would cause confusion, so he first tried it at the narrowest reef mouth. When two ships yielded to each other, they no longer waited for confirmation from the distant main tower; as long as the short light signals complied with harbor rules, nearby ships could avoid danger first, and the main tower handled only large-scale storms and port closures.
Some ships also misunderstood the short light signals, taking yield as docking. The old captain did not cancel mutual transmission, but unified the light colors, lengths, and confirmation gestures. Each ship could judge nearby, but all had to speak the same harbor language; free collaboration without common rules only makes the fog thicker. On a stormy night, this approach saved the fleet for the first time. Nearby ships avoided each other first, and distant ships then spread the news of big waves; the central tower still shone, but no longer bore the fine-grained judgment of every inch of water. From then on, the fleet had one more layer of nearby judgment.
Later, when the main lighthouse was under maintenance for a night, the bay did not shut down. The fleet moved more slowly, but did not lose control. Reliability came from shared rules, nearby communication and mutually verifiable signals.