The exhaust of every internal combustion engine used on any motorboat shall be effectively muffled by equipment so constructed and used as to muffle the total vessel noise in a reasonable manner in accordance with rules adopted by the commission. The use of cut-outs is prohibited, except for motorboats competing in a regatta or boat race approved as provided in section 462A.16 and for such motorboats while on trial run during a period from 8:00 a.m. to 6:00 p.m. not to exceed twenty-four hours immediately preceding such regatta or race.