[Missing Name]

I did the exact same thing in Scapa. Except after the first four hits, I waited a bit, danced with the escorts and fired another four for a total of six hits. Only then did I get credit by reducing it to zero points.

The problem is that if the water is shallow enough, the bottom supports the ship and keeps it from sinking. This is true for almost any of the harbors. The only real exception I've seen is Gibraltar, where the water is fairly deep.