I released IHW: Pigboats to beta testers this week. If you are interested in playtesting the game, let me know. It's not finished, but it's fully playable.
I'm slowly working on how best to incorporate AOB - or Angle On the Bow - into the game. AOB is the angle of the target's motion in relation to the direction of the sub's motion. So, if the sub is heading due north and the target is heading southeast, the AOB is Starboard 45. Most of the time, you - as the Approach Officer on the sub - want an AOB of 90 either way. However, the game abstracts that out, and you don't actually need to know the AOB out of character to shoot. Bill Downs, a gamer over on the RPGSite, gave me directions on how to make a neat AOB solver, and damn, I want to use it!
So anyway, the torpedoes can be set to run at different angles once they leave the tubes, using a gyro mechanism. Usually, you'd try to hit the target at 90 degrees. This allows the best chance for a torpedo to hit and destroy the target, as they are coming in straight onto the broadest profile, with no deflection.
However, the Mark 14 torpedoes had some awful quirks - it was a horrible mess, with four major design flaws. One of them was that the contact exploder - there was also a magnetic exploder - was prone to jamming when it hit, producing duds. However, the sharper the angle of incidence when the torpedo hit, the more likely it was that the torpedo would go off properly, as the contact firing pin was less likely to jam.
So, what I'm working with now is bonuses and penalties to the chance that the torpedo would hit - and that it would explode if it hit - depending on the AOB in relation to the TORPEDO, the Angle of Incidence. So you can solve the AOI for the torpedo, and get bonuses and/or penalties to the shot.
This would be an OPTIONAL RULE! You don't need to use it at all, but if you do, there is a reason to play with the AOB solver. :D