What is the sound signal device requirement for boats less than 12 meters in length?

For boats less than 12 meters in length, the requirement for sound signaling devices is defined by the International Regulations for Preventing Collisions at Sea (COLREGS) and the U.S. Coast Guard regulations. According to these regulations, vessels of this size are required to have a whistle, which is the primary sound signaling device.

The correct option includes a whistle, bell, and gong. However, the requirement typically focuses on the whistle primarily for signaling while navigating and in restricted visibility conditions. A bell and gong are not necessary on boats less than 12 meters; these additional devices become important for larger vessels.

This clarification points out that the principal focus for smaller vessels is on the whistle due to their operating conditions and typical signaling needs, while the inclusion of bell or gong is more relevant for larger vessels, aligning with their operational requirements in various maritime situations. Thus, while the sound signal devices listed in the correct choice include the most basic requirement, a small vessel's compliance with sound signaling laws revolves primarily around the use of a whistle.