Another trick is to use a section of 1x2 timber, say 2 feet. Dig a hole (2 feet deep), tie a piece of line the to middle of it and place the timber horizontally in the hole and close it. You will need tons of kg to pull that ground achor out by force. But when digging it up you just dig a narrow hole and lift it out by one end.

Best to place both such ground anchors to each side of the boat and tie the line off to the sidestays. This is how we all do it here in the boat parking and we have very soft sand as well. We survived all storms to date.

Wouter