just one lil ... cheat ... for you guys that have external view enabled:

set the camera on the wounded ship, and move on with your travel.
if YOU see it sink, and its outside the crews viewrange, you still get credit for sinking it.

at least im 90% sure about this.

If its a coastal merchant, I would have rammed him.

Ghost Ship
 

I'm outside New Yory in January 1942. Have already sunk a 14,000 ton Ceramic class liner in shallow water. A few days later another one comes by. I hit it with three torpedoes, it settles to the bottom but won't sink because of water depth. The funny thing is while I can see it, my crew doesn't. It also does not show up on the nav map. In the periscope it can be seen but it has no readings. I don't get credit for it either. It's a ghost ship!

Welcome Aboard! :sunny:

That's an old and well-known flaw with SH3. If the water's too shallow the ship won't sink and you can't get credit for it.