It's possible that I'm misreading this, and I'm not sure if anyone but the
US CGA would bother you, but I think you might need a longer boat to use a
really low frequency tone which lacks strength in the frequencies above 180
Hz.
**********************************
From the International Collision Regulations:
ANNEX III Technical details of sound signal appliances
1. Whistles:
Paragraph (a) is amended to read as follows:
(a) Frequencies and range of audibility
The fundamental frequency of the signal shall lie within the range 70-700Hz.
The range of audibility of the signal from a whistle shall be determined by
those frequencies, which may include the fundamental and/or one or more
higher frequencies, which lie within the range 180-700Hz (+/-1%) for a
vessel of 20 metres or more in length, or
180-2100Hz (+/-1%) for a vessel of less than 20 metres in length
and which provide the sound pressure levels specified in paragraph l(c)
below.
**************************************
Roger

http://derbyrm.mystarband.net/default.htm
"TORMAC53" wrote in message
...
I have to replace my compressor driven-12v horn. I would like to get as
much
"ship" sound as I can for 15 amps of 12volt. Any suggestions?