Depends on the boat, 5ft sections of 5/16 was plenty most of the time on my Astro but with the BassCat I use them with a 5 foot section of 1/4 hooked to each of them and it works perfect on this hull.
You dont need no god awful big chain, not looking for an anchor but something to pull, wont get hung near as bad either if its smaller. Think I hung my chains twice last year and that was while I was fishing with GitDaGrease, may not have been but once. Do know this, he had been using socks and after we fished he went and put him a chain set up together.