Yes, this works. The distance might be off by a few kms or so, but the direction is dead on, especially if you zoom in all the way to make your marks.
It's a huge cheat given the accuracy, but I had an entire thread going on how to estimate target course using the hydrophone and never really got an answer on how to do it, other than this technique.
http://www.subsim.com/radioroom/show...ght=hydrophone
Most of the guides on targeting rely on visual contact, but I hunt a lot in bad weather, and I just need an approximate course from the hydrophone so I can plot an initial intercept to get into position for the visual.