Are they phasing out the S-3 too?

On Sun, 30 Jan 2005 20:34:03 -0600, Jim Carriere
wrote:

Michael Wise wrote:
In article ,
wrote:
Since I am relying on what was taught from basic physics, I will
presume that while training might change, objective reality does not.



As I have said, I agree on most of what you've said...with the exception
that a diesel sub is easier to detect passively when snorkeling than
when running on the surface. I don't see any laws of physics supporting
that argument.

I've heard the same thing (the snorkeling sub is "noisier" in the
water than the surfaced one). More hull is in the water, so more
noise is transferred to the water and less is transferred to the air.

Bingo!!!!!!!!!!!

I'm not convinced that there is a great deal of difference, it seems
overly simplified to me. I have a feeling that water is better than
air at absorbing sound, by which I mean that a surfaced sub probably
transfers nearly all of it's engine noise to the water anyway.

No, Sir, you have backwards. :-)

Water is a most excellent transmitter of sound, while air is the Great
Absorber. The speed of sound in water at 15C is 4814 ft/sec. In air
at 15C is 752 ft/sec. This is the major reason why all that sound
radiated by a submerged hull is so detectable.

This is also why the SOSUS network, one of the really Big Secrets of
the ASW world, works so well.

For a practical application, pick up a piece of accoustic tile. I'll
bet you see a lot of air and no water!!!!! ;-)

I can understand why someone steeped in active sonar tactics might be
skeptical of passive capability. But that skepticism should be a
challenge to reconsider. The physics is pretty basic and has not
changed, no matter what the personal experience.

Bill Kambic