Section 83.35 - Sound signals in restricted visibility (Rule 35)In or near an area of restricted visibility, whether by day or night, the signals prescribed in this Rule shall be used as follows:
(a) A power-driven vessel making way through the water shall sound, at intervals of not more than 2 minutes, one prolonged blast.(b) A power-driven vessel underway but stopped and making no way through the water shall sound, at intervals of not more than 2 minutes, two prolonged blasts in succession, with an interval of about 2 seconds between them.(c) A vessel not under command; a vessel restricted in her ability to maneuver, whether underway or at anchor; a sailing vessel; a vessel engaged in fishing, whether underway or at anchor; and a vessel engaged in towing or pushing another vessel shall, instead of the signals prescribed in paragraphs (a) or (b) of this Rule, sound, at intervals of not more than 2 minutes, three blasts in succession, namely, one prolonged followed by two short blasts.(e) A vessel towed or if more than one vessel is towed the last vessel of the tow, if manned, shall at intervals of not more than 2 minutes sound four blasts in succession, namely, one prolonged followed by three short blasts. When practicable, this signal shall be made immediately after the signal made by the towing vessel.(f) When a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit they shall be regarded as a power-driven vessel and shall give the signals prescribed in paragraphs (a) or (b) of this Rule.(g) A vessel at anchor shall at intervals of not more than 1 minute ring the bell rapidly for about 5 seconds. In a vessel of 100 meters or more in length the bell shall be sounded in the forepart of the vessel and immediately after the ringing of the bell the gong shall be sounded rapidly for about 5 seconds in the after part of the vessel. A vessel at anchor may in addition sound three blasts in succession, namely, one short, one prolonged and one short blast, to give warning of her position and of the possibility of collision to an approaching vessel.(h) A vessel aground shall give the bell signal and if required the gong signal prescribed in paragraph (g) of this Rule and shall, in addition, give three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell. A vessel aground may in addition sound an appropriate whistle signal.(i) A vessel of 12 meters or more but less than 20 meters in length shall not be obliged to give the bell signals prescribed in paragraphs (g) and (h) of this Rule. However, if she does not, she shall make some other efficient sound signal at intervals of not more than 2 minutes.(j) A vessel of less than 12 meters in length shall not be obliged to give the above-mentioned signals but, if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.(k) A pilot vessel when engaged on pilotage duty may, in addition to the signals prescribed in paragraphs (a), (b) or (g) of this Rule, sound an identity signal consisting of four short blasts.(l) The following vessels shall not be required to sound signals as prescribed in paragraph (g) of this Rule when anchored in a special anchorage area designated by the Coast Guard: (i) A vessel of less than 20 meters in length; and(ii) A barge, canal boat, scow, or other nondescript craft.USCG-2012-0102, 79 FR 37912, July 2, 2014, as amended by USCG-2012-0102, 79 FR 68622, Nov. 18, 2014