Regarding the 4 bearings method there is a great tool!
Isn't the same fun like drawing the lines by hand, but for the start it's a great help!
Have a look at this:
Hydrophone tracker
http://www.subsim.com/radioroom/down...o=file&id=1711
Solution solver can be a help too!
http://www.subsim.com/radioroom/down...o=file&id=1358
regards
MiTon