Well as we've all hijacked this post may as well carry on, I think it is sonar, not radar, you mean dear Angelz, this is the underwater equivalent of radar (above surface detection). Radar is not a foolproof detector and never was, all sorts of things affect it, I have never used sonar but presume it has the same difficulties. A lesson that should be learned by all is never ever ever pin your faith on technology, it will let you down every time. Everyone took the p..s out of the Russians for using old style valves in electronics until they realised they were nuclear proof. It is no secret that by taking out two things GPS and the internet the Western forces are not exactly stuffed, but lose a lot of their abilities, think of what is reliant on these two things, no doubt our enemies do, and there will always be enemies I'm sorry to say.