Same thing happened to me aswell on my 2nd career on German side. Oddly enough, i was submerged around middle of the indian ocean, periscope up and havent seen anything and im already pinged, had plotted an attack route for a convoy and seemingly the escorts magically heard my sub going 2 knots underwater.
Anyhow, a DC popped off my rudder aswell, along with taking some damage on my hull and deck guns but most stuff i got fixed but was thinking "why the heck i cant steer" and checked the rudder. Well it was blown off... *sigh*
Yes, it should be fixable.. especially if you got that super engineer or whatever he is that can repair destroyed items..
