Hello All,
I've found that once detected and faced with a lone light warship in shallow water, a head-on ram will often either cause enough structural damage to either sink it or slow it down enough to be caught by its initial depth charge (resulting in a critical hit...if it doesn't sink it will break off attack). I usually launch a torp first, but in just case I miss, I have Plan B...you will not get a kill (unless you did hit it and it didn't sink) and will run the risk of destroying equipment on the tower, but at least you will have a great story to tell once you make it back to port.
I've had to do it 3 times, and have always managed to come out alive. All three collisions were against an single escort in years prior to 1943. When I sunk the last one, I savored the sinking of the large tanker and a medium cargo, which were left to fend for themselves, even more than I normally would have...
Happy Hunting,
Voyd