A similar thing happend to me in grid BF something when i spotted a destroyer coming at me and he hadnīt spotted me yet so i dived to periscope depht and set my engiens to stop because if he cant here me he dont know iam there. Many here has said they never encount battleships and i had nerver done that before either..so i waited and then i saw more smoke behind the destroyer and what i saw was 2 battleships!! one nelson class and one revenge class. when thay had come in range i fired 4 torpedoes at the revenge class and i hited with one. battleships usually have thick armor but it started to lean 30 degrees and i sunk it with only 2 torpedoes one under the keel so the engiens stopped the destroyers (about 9) where totally confused, i got one hit in the nelson ship but that didnt do anything to him. but i slipped away whitout damage. later on my way to base i encountered a convoy with small merchants an i only got 2 torpedoes left and succeeeded to sink one.(this was in camapign)