Coated chain
Coated chain has a tendency to corrode faster, and that corrosion is often masked by the coating.The different grades of chain offer different working loads and corrosion resistance for a given size link. Naturally, you pay more for the higher grades.The working load rating needed for your tackle is determined by the type of boat and the intended use. Don't size things to the max load, as that is generally the point of failure. The difference between working & max load is your safety margin for effects of chafe, corrosion, etc. If you only anchor occasionally for a lunch break in sheltered waters, you can use much lighter tackle (the "lunch hook" idea). If you intent to anchor where the water is rough & the winds high the shock loads will drive you to heavier tackle.It's important that your entire anchor system -- anchor, rode, connecting links, and the bitt or cleats on the boat -- be sized to the desired working load. Also, if you use power winch, make sure it has the appropriate surface for the size/type of rode (chain or rope).Your note suggests that you have a chain/rope rode. The chain (at the anchor end) primarily operates as an anti-chafe element of the rode on the bottom where there might be rocks, shells, etc. It adds a little more weight to keep the rode-to-anchor angle low, helping the anchor to set & hold. Five feet may be sufficient if your boat is small/light -- I use 20ft chain with 200ft nylon rope with a 35lb CQR anchor for my Catalina 320.The rope (nylon) portion of the rode provides most of the scope and absorbs most of the shock loads. It's a lot lighter & easier to handle than an equivalent amount of chain! Remember, all that weight is generally carried at the pointy end, tending to affect trim & handling.Check the West Marine catalog -- they have a good "Advisor page" description of anchor rode alternatives.--Ron