In fog, the duration of a prolonged whistle signal used by a power-driven vessel is

In fog, the duration of a prolonged whistle signal used by a power-driven vessel is

• A. One to two seconds
• B. Six to eight seconds
• C. Two to four seconds
• D. Four to six seconds

Answer: (D)

The main idea here is how long a prolonged whistle signal should last in fog or restricted visibility. In these conditions, a power-driven vessel uses a prolonged blast to announce its presence, and the rule defines that prolonged blast as lasting four to six seconds. This specific range ensures the signal is long enough to be clearly heard and recognized, but not so long that it muddies communication or confuses other signals. If you listen to the other durations, they don’t fit the standard: shorter times like one or two seconds are treated as short blasts, while durations longer than six seconds exceed the defined length for a prolonged blast. So the four-to-six-second window is the correct, regulation-based duration.

The main idea here is how long a prolonged whistle signal should last in fog or restricted visibility. In these conditions, a power-driven vessel uses a prolonged blast to announce its presence, and the rule defines that prolonged blast as lasting four to six seconds. This specific range ensures the signal is long enough to be clearly heard and recognized, but not so long that it muddies communication or confuses other signals.

If you listen to the other durations, they don’t fit the standard: shorter times like one or two seconds are treated as short blasts, while durations longer than six seconds exceed the defined length for a prolonged blast. So the four-to-six-second window is the correct, regulation-based duration.