Amish Ed, sounds like you may have a cartliage (meniscus) problem....especially if the knee locks up like you say it does. I'm no Doctor, but have read about knees a lot after my scopes. Good luck with the Doctor visit...they now implant cartliage into peoples knees (for arthritis)... it is supposed to help a lot! Float Tubing/Swimming don't stress the knees like running,etc...those may be the things to do now. Or...do what doesn't hurt it too much. Good Luck again with that Doctor appointment, and try not to give up surfing!