Another Das Boot Question, why when the captain realised that the Destroyer has 'warped' and was closing to the sub position, why he shouted "Close bow tubes, Dive!". Could it be more logical to just order Dive in panic state as they were?

std. OPS.
 

Outer doors,prevent leakage in to tubes at depth?

It's the 21 inch hole in the boat potential. The inner torpedo tube doors open inward, therefore the latch mechanism must work against sea pressure and depth charge shock waves in order to keep the door shut. The outer doors seat tighter with sea pressure. As in any situation, two barriers to keep the ocean out is always better as well.

In today's navy, there is lately some scientific controversy now as to whether red light is better than green light for night vision, and more and more ships are using green now instead of red. (I think its green, might some other color, I can't remember 100%) Just a little tidbit of trivia there.

Also, red light is cool in emergency situations, because it gives the ship an "urgent" feel, like "Red Alert" did in Star Trek's Enterprise!!