Bartlett,
You should use a chain snubber. It's basically a length of nylon with a chain hook on it. When your anchor is set, you hook done on the chain about 10 feet and tie off othe nylon. It adds some stretch and flexabilty to your rode.
Do a google search on "cahin snubber". Here's a description I found on the web.
"Using a Rope Snubber is easy and doesn’t take much time at all. When your anchor is set, simply place the Stainless Steel Hook over a link of chain, then let out enough chain to position the Hook about half of the distance between the anchor roller and the water. After this is done, simply make the Rope Snubber Line off on a cleat or post. Doing this will put a bit of slack in the chain and the Rope Snubber will absorb the shock load of the chain. Removing the Rope Snubber is easy too; simply pull your anchor rode up until the Stainless Hook gets close to the anchor roller. Then (if you have to use a boat hook or something similar) pull the Hook up to release the chain."