47 CFR 80.115 - Operational conditions for use of associated ship units.
(a) Associated ship units may be operated under a ship station authorization. Use of an associated ship unit is restricted as follows;
(1) It must only be operated on the safety and calling frequency 156.800 MHz or on commercial or noncommercial VHF intership frequencies appropriate to the class of ship station with which it is associated.
(2) Except for safety purposes, it must only be used to communicate with the ship station with which it is associated or with associated ship units of the same ship station. Such associated ship units may not be used from shore.
(3) It must be equipped to transmit on the frequency 156.800 MHz and at least one appropriate intership frequency.
(4) Calling must occur on the frequency 156.800 MHz unless calling and working on an intership frequency has been prearranged.
(5) Power is limited to one watt.
(6) The station must be identified by the call sign of the ship station with which it is associated and an appropriate unit designator.
(b) State or local government vehicles used to tow vessels involved in search and rescue operations are authorized to operate on maritime mobile frequencies as associated ship units. Such operations must be in accordance with paragraph (a) of this section, except that the associated ship unit: May be operated from shore; may use Distress, Safety and Calling, Intership Safety, Liaison, U.S. Coast Guard, or Maritime Control VHF intership frequencies; and may have a transmitter power of 25 watts.