A power-driven vessel underway in fog making NO way must sound what signal?

A power-driven vessel that is underway in fog but making no way must sound a signal of two prolonged blasts. This signal is part of the sound signal regulations set forth in the International Regulations for Preventing Collisions at Sea (COLREGS).

The rationale behind this specific signal is to inform other vessels that the power-driven vessel is present and operational but not moving through the water. In foggy conditions, sound signals are crucial for communication and navigational safety, as visibility is severely limited. The two prolonged blasts serve as a warning to nearby vessels, indicating the vessel's presence and helping to prevent collisions in reduced visibility conditions.

Other signals, such as one long blast or a combination of prolonged and short blasts, are designated for different scenarios, which do not apply to a vessel that is underway but making no way. Thus, understanding this signal is essential for ensuring safety on the water when visibility is compromised.