My son and I make 5' "T" posts out of 2" PVC and a 2" auger bit. Drill it into the ground using a 3/4" PVC handle put through a hole in the top. We use bungee dock tie's for the rope so it doesn't hang in the water.
We park for hours at a beach away from the bank and they don't come loose. Even boats driving by and running wake up on us.
Last weekend we had 2 other boats tied to my boat and these anchors never pulled up.
Almost every V-Drive and D-Drive on our lake has a pair.