Originally Posted by Mollers
Roycruse used to have a kazoo type thing. It was almost comical when we were caught in a total pea-souper one night.
Off topic (sort of): Had a friend who went in for a live-boat dive who surfaced to find that the skipper had decided to take a nap and drifted a cove or two south. The diver took out his emergency whistle (this particular one was sold by Zeagle, but I'm sure you've seen it: flat orange plastic thing, about 1" x 3", usually with a little belt clip molded in), blew as hard as he could, and his remark was that even he couldn't hear the noise it made. Eventually the skipper woke up and heard my buddy's swearing, so it all turned out OK (and made a decent story.)
For diving, I use a Dive Alert tank powered whistle - that thing is LOUD. On the boat I have a collection of referees brass whistles and one or two Storm whistles. As stated before I usually can't keep track of them, and loan them out (or rather give them away) so I have no clue exactly where they are.
As an aside, I was watching an episode of some Florida Fish and Wildlife reality show thing (like Cops, but with the marine enforcement guys and girls), and they ended up giving one of the Zeagle type whistles to a boater who lacked a sound signal. Not sure if they were helping or not...