The idea came to me last summer, when I waited on the beach trying to catch my son's attention for over an hour. I finally had to ask someone paddling out to tell him that his mother wanted to go home. Sometimes on a bigger swell day he just can't see me, and on days like the one last summer he just was so wrapped up in having fun that he didn't think to look.
Introducing the Surfer's Semaphore: three flags on sticks in a handy little bag. You can assign your own cue to each flag but it's a great way of catching your surfer's eye and communicating with them.