Two large ships sink every week, on average, but the cause is never studied in the same detail as an air crash. It simply gets put down to 'bad weather'.
This article also mentions 3 cruise ships, including the QE2, running into @ 30 meter waves over the past 8 years. With a bit less luck any of them could have gone down.
For years these giant waves were thought to be wild imaginings of drunken sailors. A recent satellite study shows they show up every few months. They can sink most ships.
I wonder how safe sailing ships are? I suspect they're far more dangerous than airplanes ...