NRS 488.197: Sirens.

1. No vessel may be equipped with nor shall any person use or install upon a vessel a siren, except as otherwise provided in this chapter.

2. Any authorized emergency vessel, when approved by the Department, may be equipped with a siren capable of sound audible under normal conditions from a distance of not less than 500 feet, but the siren must not be used except if the vessel is operated in response to an emergency call or in the immediate pursuit of an actual or suspected violator of the law, in which event the operator of the vessel shall sound the siren when necessary to warn persons of the approach thereof.