Heavy chain is expensive. Some years back, I got a small bleach bottle, cut off the plastic at the top of the straight sides, and filled it with cement, imbedding a 1/4 inch or 3/8 inch U bolt with nuts and washers on it to keep it in the cement so it will never get pulled out.
I added this about 3 feet above the anchor with a simple loop in the rope. Even on my 20 1/2 foot cuddy, it really digs in and holds the anchor down. No extra fastening points/knots, like would happen by adding in the chain. (fewer knots is stronger)
Trim the plastic to the top edge of the cement, so as not to ever cut your rope. (or just fill to top with cement. When hard, just keep on the plastic. (no scratching on your hull)
Holds as well, or better in my opinion than chain, costs almost nothing.