Got a couple of questions for you -

#1 - Is it true that passive sonar is relativley useless at high speeds, say 20 knots or more?

#2 - Is it true that submarines always slow to under 20 knots when in traffic zones because of #1?

Hmm... don't know a whole lot about sonar, but I can query a sonar tech today at work for you.

As far as slowing to under 20 knots... we rarely ever go that fast anyhow (though I have gone much faster) other than for sea trials or doing high speed maneuvers or something. Typically we drive around between 4 and 10 twiddling our thumbs.

That'd be nice. The question came up during a discussion about the Le Triomphant - Vanguard collision. We didn't know whether or not the Tom Clancy books would accuratley tell us about the passive sonar tech.