Yes the cooper is plastic, but has some metal on the inside for tip. Like the plastic because its light and doesnt beat around the ski.
On the shore I use
http://sandsharkanchor.com/shop/index.php?route=product/product&product_id=61 Comes apart in 3 pieces and holds in the sand with no issues.
So I basically throw out the cooper before I make it to shore, Let it grab, Cooper is connected to one of these
http://www.westmarine.com/greenfield-products--anchor-buddy-mooring-line--P005_151_002_507 bungee cables to let it flex.
The I connect the rope to the handle bars, and put in the sand shark. On the beach side where the sand shark is, I have a slip knot. So that I can tighten easily.
Sometimes if im just beaching, I will use just the sand shark anchor to keep it from floating away on me.