Steveman ok I get the picture now I like to use 3/4" galvanized chain long length that way when the working chain wears down to 1/2" you still have some protection for unexpected events like big storms and what ever else the marine world throws at it and you still have your vessel with a degree of safety. If you start out with 1/2" you end up with 1/4" hummm not where I would chose to be for my vessels investment, liability etc. not to mention your name will be on what ever you do. Ok good luck.
Any riggers or manufacturers handbook will provide specs/tolerances on iron, steel and silicon/bronze-etc. Chain if kept clean and dry 'keeps' vertually forever.There are very few silly questions and this isn't one of them. Google crosby rigging.