Sorry for my late reply. I'm sure you will rock in Boston with your combo Serenity + 10 m2 sail.
As for the 2 holes above the Serenity *windsurfing* logo on *top* of the stern's deck, there are indeed 2 holes (at 55 cm and at 65.5 cm from the stern of my Serenity mk I wood) with plugs to let you screw in 2 screws and washers to attach the Starboard rolling trolley called the "Clipper Wheels" (http://2007.star-board.com/viewpage.php?page_id=11
). These 2 holes are perfectly normal and watertight, no worries.
Cheers & enjoy your new ultralight wind weapon !
PS : for the Clipper Wheel description, please see : http://2006.star-board.com/products/accessories.asp