There seems to be a lot of buzz about anchoring with shorter scope. The only reason I can imagine this has become a popular practice is because people are lazy and the more rode you let out, the more rode you will need to pull back up.
We met a couple while anchored by the Lake Worth Bridge in Florida who were anchored with merely 40 feet of chain in 8 feet of water. Their yacht has a freeboard of 4 feet, meaning that their effective depth was 12 feet. This would produce a scope of 3.3.
Their anchor held fine and they enjoyed being anchored very close to the pier and walkway to town.
Then we all moved on and anchored in Lake Worth just at the southern end of West Palm Beach, and they anchored once again with on 50 feet in 11 feet of water. When you add their freeboard into the equation, they have an effective depth of 15 feet and a scope of 3.3 again. The difference is that now they are anchored with no protection from the current and they soon began to drag anchor.
I noticed their boat drifting through the anchorage and thought that they were moving to another place, but noticed that their chain was still led into the water and no one was at the helm. I called the owner and he rushed back to his boat to re-anchor. He decided to reanchor close to us, so I informed him how much rode we had out so that we don't swing into each other on the next tide.
I sit here anchored securely with 120 feet of chain out. This gives us a scope of 7.5 at low tide and 6.3 at high tide. He seemed shocked at how much chain we had out, yet we remain securely anchored while he had his dragging adventure through the anchorage (narrowly hitting a boat in the process).
I do fear that when the tide comes up 3 feet, he will once again drag, as his scope will be reduced to 2.7. Hopefully, he will get lucky and no one will have to fend off as he comes dragging into them because he has insufficient chain out.
