If you are operating a power driven vessel that is underway in conditions of restricted visibility, what should you do

If you are operating a power driven vessel that is underway in condition of restricted visibility, you are expected to do the following: sound prolonged blasts every two minutes. If the vessel is underway but is not moving, it is expected to sound two prolonged blast every two minutes. When one hears any of the signal above, one is expected to reduce speed to the minimum that is needed to keep on course.

The answer is true for your question.

Hope the image of the frequency formula