hail

Whistle blown to greet another boat or to signal approach to a town or woodlot in olden times. Also a signal given from shore to an approaching boat by a prospective shipper or passenger, in daylight the wave of a handkerchief or newspaper in slow, deliberate arcs, at night the wave of a lantern. The pilot of the boat, seeing the hail, recognizes it by giving a short toot on the boat's whistle. Steamboats hailed one another to transact business in mid stream after the passing signals had been completed.