I have for auction a trio of large red brass air whistles made by the
Allan Cunningham company of Seattle circa 1940, for the Federal
Electric Company. This set was on a San Francisco fire station, but
they are identical to those also used on most of the Washington state
ferries. This set of horns meets the IMO regulations for a Class II
Ship, producing 200 and 240 Hz tones in excess of 138dB (1/3 octave).
If you've got a really big boat, or wish to sound like you do, this
would be give you a really nice horn! In order to use these properly
as your main horn (capable of blowing a distress signal of at least 5
quick blasts) you need a minimum of 60 gallons of air tank at 150 psi.
The more air tank you've got, the more fun can have.

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7752654372

-Adam