46 CFR §28.240

1. (a)Except as provided in paragraph (f) of this section, each vessel with an accommodation space or a work space which is not adjacent to the operating station, must have an audible general alarm system with a contact-maker at the operating station suitable for notifying individuals on board in the event of an emergency.
2. (b)The general alarm system must be capable of notifying an individual in any accommodation space or work space where they may normally be employed.
3. (c)In a work space where background noise makes a general alarm system difficult to hear, a flashing red light must also be installed.
4. (d)Each general alarm bell and flashing red light must be identified with red lettering at least 1/2 inch (13 millimeters) high as follows:
5. (e)A general alarm system must be tested prior to operation of the vessel and at least once each week thereafter.
6. (f)A public address system or other means of alerting all individuals on board may be used in lieu of a general alarm system provided it complies with paragraphs (b), (c), and (e) of this section and can be activated from the operating station.