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
References
Bridge-to-bridge station Wikipedia(Text) CC BY-SA