Under Inland and international rules, a vessel 100 meters or more shall have what sound signal equipment?

• A. A whistle
• B. A horn
• C. A bell
• D. A gong

Answer: (D)

The main idea is that scale of equipment for sound signaling depends on vessel size, and larger ships have a specific device to ensure a loud, lasting signal can be heard over distance and in various conditions. A gong is the sound-signaling device specified for vessels 100 meters or more because its deep, resonant tone travels well across the water and through background noise, making it effective for attracting attention and indicating the vessel’s presence when other signals might be harder to hear. While whistles (or horns) are also common signaling tools, the gong is the device highlighted for very large ships to ensure a clear, enduring audible cue in restricted visibility or busy waters.