Just a few days ago on a patrol, while I was trying like heck to put myself in the middle of a convoy I was tracking with periodic hydrophone checks in crappy weather, a destroyer came charging out of the fog a few small hundred meters away.
His first shot smashed one of my diesels as he did his best to ram me. Thanks to my slow speed and wrecked diesel, my crashdive took a lot longer than usual.
He had to find me via radar. No other explaination.
Some days earlier in the same patrol at dawn, I spotted one of Rubini's Swordfish carrying a sound homing / U-boat crunching torpedo...
Both events were scary and got my blood pressure up, but the Sworfish hunting with that torpedo almost gave me a heart attack... even though he didn't spot us in the poor light.
