This sand anchor looks like it will really do the job.  The one they sent me is solid white (which I prefer), and not the blue color shown in the photo.  It''s long, with a screw on the bottom, and handle for pulling it out of the sand, and a cinch-down knob to secure your umbrella to it tightly.  Looks like it will do a very good job of holding my umbrella in place.  I''m very pleased with it.