Made first contact with a convoy in OM. and noticed that there appeared to be ships in it with fires. I thought it was a nice touch. I'm told that you can't spawn ships with pre-existing damage, so I'm now wondering if that's actually what I saw. As luck would have it, I managed to get some screenshots. The smoke looks different and there's a faint orange dot, that could be fire, although it's not visible through the binocs. I didn't see any damaged ships once I was in amongst the convoy, but I was submerged and it was a big convoy. They could have been there without me seeing them.
The real bummer was that I didn't save after attacking [or during] and the game crashed on my way home through the Dover Straits, so I ended up going back to a previous position and I never saw this bunch again

Anyway, here are the screenshots. To me they look like ships are on fire, but I concede it's far from conclusive - What do people think?