When I was 12, I almost drowned. The next thing I knew I was on the deck with the lifeguard. I believe you pass out from the stress. That’s what seems to have happened in my experience.
The idea that it's a frightening but quick and painless end will be no comfort to families of the sailors. But in a situation like this hard decisions such as sealing off water tight compartments must be made. Whoever made that call will have to live with it the rest of his life.
That happened to a friend of mine when he was a kid, too. He said it was the most excruciatingly painful thing he had ever experienced, before or since, and that he was writhing and kicking in agony under water. Then just before he lost consciousness, his body relaxed and the pain and fear vanished, and he was at peace with it.