Bridge-to-bridge station

In telecommunication, a bridge-to-bridge station is a ship station[?] operating in the port operations service[?] in which messages are restricted to navigational communications and which is capable of operation from the ship's navigational bridge or, in the case of a dredge, from its main control station[?], operating on a frequency or frequencies in the 156-162 MHz band.

Source: from Federal Standard 1037C and from the NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management