What is the fog signal for a vessel under power at two-minute intervals?

• A. One prolonged blast
• B. Two short blasts
• C. Three short blasts and one long
• D. One short blast every minute

Answer: (A)

When a power-driven vessel is underway in fog or restricted visibility, the signal to use is a single prolonged blast, repeated at about two-minute intervals. This pattern clearly communicates the vessel’s presence and that it is making way, helping others avoid collisions. The other signals described are used for different situations (such as overtaking, meeting, or other specific messages) and do not fit the two-minute interval rule for a vessel under power in fog. So the best answer is the one prolonged blast, repeated every two minutes.