Just wanted to add my 2 cts to hellosailor's thoughts. I believe that this is easily overlooked by many, myself included.
We probably would tell somebody, "Hey, I"m going to swim across the lake". And that person would keep an eye out for us, grow concerned if they didn't see us, etc...
But, this time of year, I just hop on the boat and away I go. Well, it won't be much longer before our water will be down around 50 degrees and that's about 50 mins survival time. Do I really want to wait for someone to notice I'm capsized? Someone thinking, "he ought to be back by now" is pretty cheap insurance. Heck, we do it when we go to the grocery store, why should my macho bs preclude me from doing it for a quick sail? I like my macho bs but stupidity always trumps it!