Rules of the Road: INLAND ONLY You are overtaking another power-driven vessel and sound a whistle s...

The vessel is displaying an emergency signal with 5 short blasts. It only makes sense to halt until you understand what situation the "vessel not under command" is facing to safely overtake the vessel in distress and to determine the most appropriate way to overtake them.

Actually, the stand-on vessel’s 5 short signal likely has nothing to do with her having an emergency. This is an INLAND only question, so refer to Rule 34 (a) (Ii) which basically says that after you sound one short blast indicating your intention to pass the vessel on her starboard side, she has two options. If she agrees, she returns your one blast signal. “If, however, from any cause, the vessel doubts the safety of the proposed maneuver, she shall sound the danger signal...” in effect the 5 short signal is saying “ I don’t think it is safe for you to overtake me on that side” (for any reason).