Regulation 33 Supply of electrical energy
At all times while a radiotelephone ship is at sea, and at all reasonable times while she is in port, there shall be available a main source of energy sufficient to operate the installation over the normal range of not less than 150 miles. If batteries are provided they shall have sufficient capacity and shall be maintained at all times while at sea in such condition as to be able to supply continuously for at least six hours a total current equal to the sum of—
the current consumption of the radiotelephone receiver and of the transmitter when it is in a condition that operation of the “press to transmit” switch will make it ready for the immediate transmission of speech;
one third of the current which may be drawn by the radiotelephone transmitter for speech transmission on the frequency at which the current consumption of the transmitter is at a maximum;
the current consumption of all additional loads to which the battery may supply energy in time of distress or emergency; and
where the source of energy is also used by the VHF radiotelephone installation, the current consumption of the VHF radiotelephone receiver and one fifth of the current consumption of the VHF radiotelephone transmitter.
In respect of installations in United Kingdom cargo ships of 300 tons or more, and other cargo ships of 500 tons or more but in any case less than 1,600 tons, made on or after 19th November 1952, a reserve source of energy shall be provided in the upper part of the ship unless the main source of energy is situated there.
The reserve source of energy, if provided, may be used only to supply—
the radiotelephone installation;
the emergency light specified in regulation 29(4) of this Part;
the device for generating the radiotelephone alarm signal by automatic means;
the VHF installation;
the direction-finder (if fitted); and
reasonable number of low-power emergency circuits which are wholly confined to the upper part of the ship, such as emergency lighting on the boat deck. Such reasonable number of circuits shall be adequately fused and capable of being readily disconnected from the reserve source of energy.