LOL, wouldn't the sub already be an easy target for any other subs lurking above the layer? Thats why subs stay above and arrays sink, so they can hear the sub below but the sub below can't hear them.

Heared about it several times but still don't understand the mechanic of it.

Deamon

http://www.sfu.ca/casr/101-navvds.htm
This link tells about the Canadians VDS that they use on one of their Iroqouis class destroyers. From what they say it sounds like this set is active only, kind of like a giant dipping sonar set.
http://www.sfu.ca/casr/navvds-2.jpg

Skimmers don't have to come to periscope depth to receive/send comms or for ELINT missions. The array is slightly negative so the array can go below the layer while at slow speeds while you (the platform) are above the layer. It also allow streaming the array while at PD.

The floating wire antenna will float at the surface, but the drawback of it, particularly near land, is that seagulls will actually sit on the wire. Too bad that isn't modeled in DW or SC.