Mike, I found a pair of sunglasses that look similar to those on the floor next to a table on the first level of the boat. This was after all the guests left and I was looking for my bag (see
http://www.gofuckyourself.com/showthread.php?t=757510).
I picked them up and put them on the closest table. I figured the owner would do the most logical thing and come back to look on the boat.
If you didn't get them yet, contact the boat operator. Their policy is to turn in lost items to the co-ordinator. Since I was the last guest on the boat, it's very unlikely another guest picked them up.