BOTH INTERNATIONAL & INLAND Which is the duration of each prolonged blast on whistle signals used by a power-driven vessel in fog, whether making way or underway but not making way?

Correct Answer: Option C — four to six seconds

Rule 35(a) defines a prolonged blast as a blast of four to six seconds duration. This signal is required for power-driven vessels making way through the water in or near an area of restricted visibility to alert other vessels of their presence and status.