33 C.F.R. § 150.720 What are the requirements for sound signals?
Title 33 - Navigation and Navigable Waters
The sound signal on each pumping platform complex must be operated whenever the visibility in any horizontal direction from the structure is less than 5 miles. If the platform is under construction, this requirement may be met by the use of a 2-second whistle blast, made every 20 seconds by a vessel moored at the platform.
Title 33: Navigation and Navigable Waters
PART 150—DEEPWATER PORTS: OPERATIONS
Subpart H—Aids to Navigation
§ 150.720 What are the requirements for sound signals?
