The word is derived either from naus (ναῦς "a ship") and describes the duty imposed upon each naucrary, of providing one ship and two (or, more probably, ten) horsemen; or from naio (ναίω "I dwell"), in which case it has to do with a householder census. The former is generally accepted in view of the fact that the naucraries were certainly the units on which the Athenian fleet was based.
The view once held (on the strength of a fragment of Aristotle, quoted carelessly by Photius) that the naucrary was invented by Solon may now be regarded as obsolete (see the Aristotelian Constitution, viii. 3). Each of the four Ionian tribes was divided into three trittyes ("thirds"), each of which was subdivided into four naucraries; there were thus 48 naucraries.
The earliest mention of the term is in Herodotus (v. 71), where it is stated that the Cylonian conspiracy was put down by the "Prytaneis (chief men) of the Naucraries." Although it is generally recognized that in this passage we can trace an attempt to shift the responsibility for the murder of the suppliants from the archon Megacles, it is highly improbable that the Prytaneis of the Naucraries did not play a part in the tragedy.
Thucydides is probably right, as against Herodotus, in asserting that the nine archons formed the Athenian executive at this period. It may be conjectured, however, that the military forces of Athens were organized on the basis of the naucraries, and that it was the duty of the presidents of these districts to raise the local levies. It is certainly remarkable that the Aristotelian Constitution of Athens does not connect the naucrary with the fleet or the army; from chapter viii. it would appear that its importance was chiefly in connection with finance.
The naucrary consisted of a number of villages, and was, therefore, a local unit very much in the power of the naucraros, who was selected by reason of wealth. The naucraros superintended the construction of, and afterwards captained, the ship, and also assessed and administered the taxes in his own area.
In the reforms of Cleisthenes, the naucraries gave place to the demes as the political unit. In accordance with the new decimal system, their number was increased to fifty. Whether they continued (and if so, how long) to supply one ship and two (or ten) horsemen each is not certainly known. Cheidemus in Photius asserts that they did, and his statement is to a certain extent corroborated by Herodotus (vi. 89) who records that, in the Aeginetan War before the Persian Invasion, the Athenian fleet numbered only fifty sail.