NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Noisy Sea Surface
From: Rodney Myrvaagnes
Date: 2003 Nov 15, 16:41 -0500
From: Rodney Myrvaagnes
Date: 2003 Nov 15, 16:41 -0500
On Sat, 15 Nov 2003 20:36:57 +0000, George Huxtable wrote: > >That is: they are certainly individual clicks and not at all drawn-out >"scrapes". They are heard from below decks, the sound being transmitted >through the water and the hull, and not (or at least, very attenuated) from >on deck. I have heard many clicks per second, but these seem to be from >multiple sources, from all around the hull, not just from one or two >clickers, clicking madly from one place. > This sounds like the same thing I heard in San Diego. Sound indeed is attenuated greatly as it passes through a surface between media of hugely different density. Think of how little the water surface would move for even a strong signal. I don't think the songs of Humpack whales are ever heard in the air. If they can be, I must have seen a lot of mute whales. The one exception I have experienced must have resulted from kilowatts into a hydrophone. When a US submarine is about to surface, it announces this in a stentorian but disembodied voice. It is unnerving, particularly because there is nothing you can do to stay out of the way, since you don't know exactly where it will emerge. Rodney Myrvaagnes J36 Gjo/a A Great White dorsal fin, close enough alongside that the tail fin was outside peripheral vision