Section 67.30-10 - Sound signals(a) The owner of a Class "C" structure shall install a sound signal if:(1) The structure is erected on or adjacent to the edge of a:(iii) Line of demarcation; and(2) The District Commander decides it is necessary for the safety of marine commerce.(b) Sound signals required by paragraph (a) of this section must have rated range of at least one-half mile, unless the District Commander prescribes a greater rated range, not to exceed 2 miles.(c) The owner of the structure shall operate the sound signal required by paragraph (a) of this section whenever the visibility in any direction is less than 3 miles, unless the District Commander establishes a greater or lesser distance of visibility, not to exceed 5 miles.(d) Class "C" structures may have sound signals if:(1) Authorized by the District Commander under the provisions of Subpart 66.01 of this subchapter; and(2) The sound signal meets the requirements of § 67.10-1 (a) and (b) .CGD 72-74R, 37 FR 13513, July 8, 1972