Which sound-producing device is mandated for engine-powered vessels 26 feet or longer?

Engine-powered vessels that are 26 feet or longer are required to be equipped with a sound-producing device that is effective for signaling and communication on the water. The requirement for a whistle that is audible for at least one mile is highly pertinent in maintaining safety and ensuring that vessels can signal their presence or intentions to other nearby boats. This type of whistle allows for clear, long-distance communication, which is essential in busy waterways or during low visibility conditions such as fog.

The other sound-producing devices listed may serve specific purposes or be useful in different situations, but they do not meet the mandated requirements for vessels of this size. A handheld electric siren may not provide the necessary audibility range or might be impractical for regular boating situations. A horn capable of producing a sharp sound could potentially suit some situations, but it might not meet the specific audible range requirement. Similarly, while a bell is an important signaling device, it is traditionally not required for larger vessels in the same way as a whistle is. Therefore, the whistle's capacity to be heard from a mile away ensures it fulfills the legal and safety standards for larger vessels on the water.