Welcome, and might I suggest you build yourself an attack disk/whiz wheel:
And learn how to use it. Very handy tool to have.
You can get the templates to make it in this thread:
http://www.subsim.com/radioroom/showthread.php?t=114351
And you can get the instruction booklet on how to use it in this thread:
http://www.subsim.com/radioroom/showthread.php?t=126824