I has a customer who owns a 40ft yacht that when he designed and built it about 20 years ago he thought he would use it mainly for racing, now he wants to only cruise on it.
Anyway, he put a Maxwell anchor winch on it with an 8mm chain gypsy, 8mm chain being fine for racing but on a recent cruising trip he actually stretched the 8mm grade 'L' anchor chain!
So first option was to put a 10mm chain gypsy but that was $500 plus atleast that again for newe chain. So with some research I supplied him with 8mm PWB Grade 70 (also called transport or high tensile) chain and he took it to the local galvinizers. They told him after taking the zinc coating off and re galvinizing he would loose 10% strength.
Now as well as suppling marine gear i also work for a lifting company with a 25t test bed so he gave me a short length of chain to blow up! The 'lashing capacity' of the chain is 3800kg with an approx safety factor of 2:1.
It pulled to 6000kg and still didn't deform at all and that was as high as I could go before the shackles I had to use started to go!!
So if you need stronger chain, there is now another option!!!