PzKpfw IV sinks destroyer?

One little thing to note is that the German Naval 88mm mounted on U Boats was not the same weapon as the famous 88mm AA weapon (of which there were several versions with slightly differing capabilities).
A little bit of a red herring in regards to a U Boat gun and the ones at Tobruk used for AA defense being comparable in the anti ship role.

 

I didn't mean to imply that Sikh was actually sunk by an 88 just that DD's were not necessarily proof vs one.