Headscratchers / Down Periscope

• Why would Lake believe Dodge when he said he didn't have dive training? She specifically states during the first dive that she looked up his scores herself to compare them to hers.
  • At the time, she lacked confidence in herself and was stressing out. When that happens, you tend to forget certain details.
  • She doesn't believe him. She even asks how long he was going to wait for her to jump in before stopping faking and do it properly himself. She does believe he is faking in order to give her a chance to get her confidence back, which she eventually does.
  • Dodge didn't say he never had dive training. He said he was guessing alluding to an earlier conversation about Lake scoring higher on simulations than he had. He was implying to her that she was better for the operation to boost her confidence.
  • He never explicitly said he didn't have dive training. All he said was "I'm guessing here" but more as "I haven't had to do something like this in years and I'm rusty" than "I have no clue what I'm doing at all" - As shown in a later scene, it was a ruse to get Lt. Lake to step up and take control as he would have done it himself correctly half-a-heartbeat later. It was more or less as Secret Test of Character
• What did Admiral Graham actually hope to accomplish in the second half of the movie? By successfully "attacking" Charleston, Dodge had pretty much already confirmed Winslow's theory that such an attack was possible. Norfolk was only gravy and really would only prove they could stop such an attack when they absolutely knew where and when it was coming.
  • That is the whole point of his character, he's letting his own pride and his own personal dislike of Dodge get in the way of his own best judgement. That is why he is told that his own promotion is being nixed at the end.
  • For Graham, it wasn't about proving Winslow's theory wrong - it was about beating Dodge and "winning" the wargame by sinking the Stingray. He boasts how he's never lost, and apparently that adds enough to his career to push him to a promotion. Cheating by narrowing the engagement area (and then committing a cardinal sin in the US Navy by taking command away from Knox) was more about his obsessive need to win than shutting down Winslow. And even regarding Winslow's theory, Dodge launching a flare in Charleston could be passed off as a fluke - a highly trained US Navy ship captain would certainly be familiar with his own force's tactics and would know how to beat them, after all - but two penetrations, one of a heavily guarded harbor (they had three destroyers, a frigate, and a nuclear attack sub with air support against one incredibly outdated sub), is a lot harder for the Navy to ignore.
• Why did Orlando surface to chase Stingray in the finale? Los Angeles class subs are designed to operate underwater, they rarely surface. She's 5+ knots faster submerged. It would actually be more difficult to close the range on the surface.
  • To communicate via radio, probably.