Distress signals. The following signals, used or exhibited either together or separately, indicate distress and need of assistance:
(a) a gun or other explosive signal fired at intervals of about a minute; (b) a continuous sounding with any fog-signalling apparatus; (c) rockets or shells, throwing red stars fired one at a time at short intervals; (d) a signal made by radiotelegraphy or by any other signalling method consisting of the group ... – – –... (SOS) in the Morse Code; ...