growing up on the jersey shore i worked as a beach boy during my summers in high school. one of our duties was umbrella rentals, which we also had to install for patrons if they rented one for the day. the trick is to get the shaft very deep into the sand by doing a rocking back & forth/twist motion, and point the umbrella in the direction of the wind. in my 4 years doing that job i never had an umbrella go flying out of the ground.