Many brave kittens lost their lives to bring you that information!
Back when i was active in SH3, i lost a couple boats to similar cicurmstances. One off Curraoca, and the other off New york. I was puttering around in a pea soup fog and out of nowhere came the knife like bow from the fog like some really bad horror movie. The boat i lost off New York was particuarlly memorable since i only had 30-40 meters of water underneath the keel. My stern fell out from under me and was the first to hit bottom, followed quickly by the bow. Sat there on the bottom, flooded to the gills with water as he commenced his runs. All i could do was sit there and hope he was an idiot, but i knew i was screwed. I think he got a bullseye on his fifth run, and that was all she wrote.