I found one inside a port in the west side of the channel. It was before I installed the IRAI, so it wasn't much of a trick getting it downed either. That, and two troop transports went down with the surrounding destroyers just hanging around, casually looking the other way. That's when I rushed to these forums to get IRAI, ASAP
Prior to that, I sunk HMS Queen Mary in Scapa Flow. It is alot of fun sneaking into enemy ports, I must say. But I presume impossible with IRAI. I did it alot in SH3 and 4 though.