I started off doing this with a bungee cord inside a piece of tubular nylon webbing. Like you I got a 2:1 extended to contracted ratio. That year in the Bahamas I talked to another boater who had used surgical rubber tubing inside a piece of polypropylene hollow core water ski rope. He had a better ratio than I did, so I set out to copy his setup. Before I got around to it, I ran across an Airhead Anchor Bungee and bought it. It has rubber bands inside its ski rope and gets a ratio of 3.5:1. I bought it and replaced the plated steel hardware with stainless. https://www.amazon.com/Airhead-AHAB...fd-8c96-d944a4360a5c&pd_rd_i=B00SMDQW3Q&psc=1 Others have what appears to be the same but cheaper. https://www.amazon.com/Greenfield-P...fd-8c96-d944a4360a5c&pd_rd_i=B003BM5LUI&psc=1To add a detail to the above post, it is 50' of 1/4" bungie cord placed inside 100' of polypropylene hollow braid: https://www.amazon.com/Hollow-Braid-Polypropylene-Rope-inch/dp/B01N81EG0R?th=1
The hollow braid protects the bungie. We use yellow color because it is easy for others to see that there is a stern line out. The 2:1 length is necessary to accommodate the bungie stretch.
The trick is in judging the distance correctly. The other day I dropped it a bit too far out coming into a dock and just as Michele was about to step off the dinghy we started slingshotting backward...
Mark
And yes, judging the distance from where the anchor bites to the beach is a challenge. I added a bit of rope to the dinghy end of it to compensate for my shortfalls.... or should that be long falls.