E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
in sailor language has no reference to age, but only to experience in seamanship. A boy may be fifty or any other age. A crew is divided into able seamen, ordinary seamen, and boys or greenhorns. A boy is not required to know anything about the practical working of the vessel, but an able seaman must know all his duties and be able to perform them.