Automatic marine warning system

An automatic electronic marine warning system for use under conditions of reduced visibility is described. The heart of the system is a rapid ringing bell for fog warning at anchor. A bell tone was recorded and analyzed, and simple electronic circuits were developed to produce a tone approximating this bell sound. Other circuits include a foghorn signal with electronic timing circuits for sounding either the foghorn or bell at intervals appropriate to the situation. Associated with this system is a loud hailer and listener, and provisions for monitoring the outputs of communications receivers or other audio circuits. The system operates from a 12-volt dc supply and is designed for use on small vessels where limited operating personnel are available.