On Fri, 20 Jan 2006 08:49:51 -0800, markvictor wrote:

3721 mph, but that would be in a submarine, not on the surface, at sea
level, the nasa standard table puts SOS at sea level in daytime at
761mph...so that is what a surface vessel would have to achieve to break
the sound barrier; even a displacement hull is still floating on the
surface of th water, so it wold be subject to gas physics.A boat on the
surface is exerting a fixed force on the water (in a perfect world),
this force remains more or less constant, varying onle due to lift and
loss of it while moving, this will not generate a fast enough shock wave
through water to cause a "sonic boom"

The eventuality of a "sonic boom" underwater may not be that far off. The
Russian supercavitation torpedo, the Shkval, has a speed of 350 km/h, and
was operational in the '70s. The German Barracuda being developed is
expected to reach 800 km/h. Supercavitation may be old technology. With
magnetohydrodynamic torpedoes, speeds of 1700 mph may have already been
reached.

http://www.defensetech.org/archives/001688.html

http://www.fas.org/man/dod-101/sys/m...row/shkval.htm

http://saifudin.com/2005/09/04/super...e-hardly-know/