What equipment must any vessel over 100 meters have to signal an impending danger?

For vessels over 100 meters, one of the essential requirements for signaling impending danger is the use of a gong. The International Regulations for Preventing Collisions at Sea (COLREGs) specify that vessels of this size must carry specific sound signaling equipment, including a gong, to make their presence known in situations where visibility is limited, such as fog or other poor weather conditions.

A gong is an effective means of sound signaling, particularly in heavy weather or low visibility, where the sound can carry over longer distances compared to other signaling devices. The use of a gong helps to ensure safety by allowing other vessels in the vicinity to be alerted to the presence and intentions of larger vessels.

While whistles, foghorns, and light signals are indeed used for marine communication and can serve their purpose in various scenarios, they do not meet the specific regulatory requirement for vessels exceeding 100 meters. Therefore, having a gong on board is critical for compliance and safety in maritime navigation.