Well, first question is are there sandbars around the area from where they they made their last check-in? Aren't sandbars usually relatively close to shore? Could police examine the bottom of the boad for any signs of damage?
This theory does fit in well with the idea of the clothing being folded on the deck, along with the hats and sunglasses missing.
After having been unable to get the GPS system to work due to USER ERROR and having to go back to their original departure point to learn that the problem was their own lack of knowledge about the equipment, perhaps when they ran aground on a sandbar they were determined NOT to calll anyone for assistance. So they would not look stupid.
So the scenario would be: The main sail is up, the boat is in idle, they go into the water over the side in order to try to free the boat.
Once when stuck on a sandbar in Baltimore Harbor, Chesapeake Bay (Yes, yes - we were looking right over at Fort McHenry where the battle about which Francis Scott Key wrote the Star Spangled Banner, and .......) Anyway, what we did was run from the front of the boat to the back of the boat - 6 people to the front, then quick, 6 people to the back, trying to "rock the boat" off a sandbar. Eventually, another boater came to our rescue and pulled us off the sandbar.)
But my point is that "rocking the boat" is a time tested method for removing a boat run aground on a sandbar. Could these gentlemen have thrown those bumpers over the side so they would have three ropes to use for pullling on the boat from in the water? They all three pull hard at the same time and the boat frees itself right at the time a wind comes along and picks up the sail. And it is bye-bye.
Question: why would not ONE of them think of donning a lifejacket before attempting something like this?
But the fact that not one of the three was able to figure out he GPS system leads me to believe that perhaps there was some befuddlement among these men. Who sails off for a journey without checking all equipment, especially a GPS, to make sure it is working?
Also, if they were close enough to shore to have encountered a sandbar, aren't the chances good that at least one body would have turned up by now?