BOTH INTERNATIONAL & INLAND You are at anchor in fog. The fog signal of a vessel underway has been steadily growing louder and the danger of collision appears to exist. In addition to your fog signal, what signal may be used to indicate the presence of your vessel?

Correct Answer: Option A — Three blasts on the whistle; one short, one prolonged, and one short.

Rule 35(g) allows a vessel at anchor to sound a whistle signal of one short, one prolonged, and one short blast to warn an approaching vessel. This is an optional, supplementary signal used specifically when there is a risk of collision to ensure the vessel's presence is known.