WoW, This post lasted a long time!!
Lets see, going back in time when I was long haired hippy, or had any hair... I remember some one saying the song was about a U.S, Navy spy ship that was captured by North Korean gun boats around late 60's early 70's. The Captian is a man named Commander Booker. When norh Korea was trying to capture the ship the sailor were calling MAY-DAY to all ships, while the sailors were burning top secret docs then the gun boats started shelling the spy ship, the U.S. Navy ordered our war ships to stand down (not help)because the spy ship was now in Korean waters. The spy ships named USS Pueblo which caused an international incident. If it makes sense, on your Mystery ship, no one heard them calling, no one came at all. They also sailed out of San Fransisco navy base. But I don't get the 73 men part, I think they had 98? some other number?