North Carolina General Statutes Chapter 75A. Boating and Water Safety § 75A-9. Muffling devices

(a) Every internal combustion engine used on a vessel shall have effective muffling equipment installed and used on the exhaust to muffle the noise in a reasonable manner. The use of cutouts is prohibited.

(b) Every internal combustion engine with an open-air exhaust that is used on a vessel that has a capacity of operating at more than 4,000 revolutions per minute shall have effective muffling equipment installed and used on each exhaust manifold stack. This subsection shall not apply to a licensed commercial fishing vessel.

(c) This section shall not apply to vessels competing in a regatta or race approved by the United States Coast Guard, for such vessels while on trial runs during a period not to exceed 48 hours immediately preceding the regatta or race, and for such vessels while competing in official trials for speed records during a period not to exceed 48 hours immediately following the regatta or race.