(c) A sailing vessel under way shall sound at intervals of not more than one minute, when on the starboard tack one blast, when on the port tack two blasts in succession, and when with the wind abaft the beam three blasts in succession.
(d) A vessel when at anchor shall at intervals of not more than one minute ring the bell rapidly for about five seconds.
(e) A vessel at anchor at sea, when not in ordinary anchorage ground and when in such a position as to be an obstruction to vessels under way, shall sound, if a steam vessel, at intervals of not more than two minutes, two prolonged blasts with her whistle or siren, followed by ringing her bell, or if a sailing vessel, at intervals of not more than one minute, two blasts with her fog horn, followed by ringing her bell.
(f) A vessel when towing shall, instead of the signals prescribed in subdivisions (a) and (c) of this article, at intervals of not more than two minutes sound three blasts in succession, namely, one prolonged blast followed by two short blasts. A vessel towed may give this signal, and she shall not give any other.
(g) A steam vessel wishing to indicate to another "The way is off my vessel; you may feel your way past me" may sound three blasts in succession—namely, short, long, short—with intervals of about one second between them.
(h) A vessel employed in laying or picking up a telegraph cable shall on hearing the fog signal of an approaching vessel sound in answer three prolonged blasts in succession.
(i) A vessel under way which is unable to get out of the way of an approaching vessel through being not under command or unable to maneuver as required by these rules shall on hearing the fog signal of an approaching vessel sound in answer four short blasts in succession.
Sailing vessels and boats of less than 20 tons gross tonnage shall not be obliged to give the above-mentioned signals, but if they do not they shall make some other efficient sound signal at intervals of not more than one minute.
SPEED OF SHIPS TO BE MODERATE IN FOG, ETC.
ART. 16. Every vessel shall in a fog, mist, falling snow, or heavy rain storms go at a moderate speed, having careful regard to the existing circumstances and conditions.