just happend to me as well.
Tho i did find one Brit T2 & a couple little merchants. i did mistakenly hit an american C3 but it didnt sink...i guess i'm happy about that.
Due to this experience tho i now see why the u-boat skippers were often quite glad when Germany declared war on america. I mean the ^&(*() have been shipping supplies to England and making it harder for me to sink the British ships by mixing in with them.
And no my wife wasn't very symapthetic to my frustration either.
Just try to look forward to Drumbeat & we'll make them pay then!!