Bottom is a mix of sand and rocks...not exactly sure what was at the top mark since we managed to escape unscathed. Pretty sure your boards are OK, at least they seemed fast enough for the rest of racing! If not, I've got a guy that can make them brand new for less than the cost of a quart of 2-part epoxy paint.

Link to photos: http://www.youtube.com/watch?v=iMLiqXAG5sI