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WAC 352-60-065 Sound producing devices. No person shall operate, or permit to be operated, a vessel on the waters of this state without sound producing devices as follows: (1) A vessel of twelve meters (39.4 feet) or more in length shall be provided with a whistle and a bell and a vessel of one hundred meters (328.1 feet) or more in length shall, in addition, be provided with a gong, the tone and sound of which cannot be confused with that of the bell. The whistle, bell and gong shall comply with Chapter 33, Code of Federal Regulations, Part 86. The bell or gong, or both, may be replaced by other equipment having the same respective sound characteristics, provided that manual sounding of the prescribed signals shall always be possible. (2) A vessel of less than twelve meters (39.4 feet) in length shall not be obliged to carry the sound signaling appliances prescribed in subsection (1) of this section, but if she does not, she shall be provided with some other means of making an efficient sound signal.How loud can you scream?
Any vessel is required to have a sound producing device, i.e. whistle, air horn, etc. It does not matter what body of water or propulsion type.
More uses for air horns...
lot's of other uses too