I haven't lost a single gaitor since...
Losing gaitors in the surf or river was a common occurrence for me. I know I was not alone because I would find as many as I lost, keeping an average of 6 in my possession thru the course of a season.
I have not lost a single one, and have negligible amounts of sand in my boots since I adopted a very simple technique... a duct tape keeper!
Starting with the fashion ignorant gray standard, I have eventually upgraded to black duct tape to match my black scuba boots and black neoprene gaitors. After a remark on my lack of GQ by Lefty, I had to color coordinate. Can't even tell they're there now.
Black is easy to find. When I bought the roll, the guy at the HW store showed me the camo duct tape he says is a must for hunters. Not all that uncommon for sportsmen at all according to him. Anyway, anything over 1.5 wraps will not come off even after a full day of wading in the Nauset surf.
I usually keep the last 10 feet of the roll in the back compartment of my chest pack in case I need to swim with my waders on. I figure sealing the top of my waders could save my life someday.
Maybe that's why mountain climbers call it "Jesus on a roll".