Under Rule 33, what signal is required for vessels over 100 meters?

• A. Whistle
• B. Whistle and bell
• C. Whistle, bell, gong
• D. Gong

Answer: (C)

Rule 33 requires that vessels 100 meters or more in length be equipped to give the full set of standard sound signals. The combination of a whistle, a bell, and a gong covers the range of signals used to communicate intentions and presence in traffic, especially in restricted visibility or crowded areas. The whistle is the primary device for the common navigational blasts (prolonged and short) that indicate maneuvers like turns or overtaking. The bell and the gong provide distinct audible signals that can be heard in closer quarters and under different conditions, helping other vessels recognize the large ship’s presence and actions. A vessel must have all three devices to meet the rule; using only a whistle, or only a whistle and bell, or only a gong would not fulfill the required signaling equipment for vessels of that size.