Question 366 Rules of the Road

The correct answer is D) is moving from a dock. According to the U.S. Coast Guard regulations, a prolonged blast (4-6 seconds) from a vessel's whistle or horn while underway in a harbor indicates that the vessel is moving from a dock, pier, or other mooring into the channel. This signal is used to alert other vessels in the vicinity that the vessel is getting underway and entering the navigable waters. The other options are incorrect because: A) a series of short blasts would indicate the desire to overtake your vessel, B) a single prolonged blast from an anchored vessel would indicate that the vessel is at anchor, and C) a series of short, rapid blasts would indicate that the vessel is backing her engines.