Really, I'm gonna have to go with ETR3 on this one. Got curious about this and checked out that link, and ETR3 is correct, the fellow who wrote that makes no mention at all regarding the capabilities of the equipment to receive or transmit while submerged at any depth. Here's another link that sort of covers the subject, and explains exactly why a submerged boat would not be able to transmit at all on any frequency, but could recieve a VLF (very low frequency) signal.
http://en.wikipedia.org/wiki/Communi...ith_submarines