It is virtually a rope circle, with your boat forming part of the rope.
Need two anchors.
Tie a rope to the stern cleat,with an anchor attached, but not tied off Hold onto the end of the rope in the boat, and set the anchor.
Then motor to shore, letting the stern rope out as you go.
Unload, then pull the boat out, into deeper water, using the stern rope.
Set the bow anchor, on the beach, attached to the bow.
Tie the stern rope off to the same anchor. You can retrieve the boat , and pull it back out again, as many times as you like.
David