I just saw All is Lost (really good movie btw
http://www.imdb.com/title/tt2017038/ ) and I had a question for people who know about boats. Limited spoilers follow- In the movie Robert Redford's boat gets ****ed up and he has to flee to a life raft and try to survive at sea. While he is on the life raft there is a survival kit with water/compass/flares/etc. So he is floating there for a while and eventually a huge cargo ship comes by and he has to try to get its attention which is really difficult obviously. So he shoots his flares and waves his arms and stuff. I had the thought of why wouldn't a basic survival kit contain an air horn? Wouldn't that be something that would be cheap/useful/not take up much space? But then I thought maybe a big ship would drown out the sound of an air horn so it would be worthless. So the question is- in that situation would a ship be able to hear a standard air horn from someone on a life raft?