A tech guy at Samson ropes told me a few years ago that when synthetic rope is tested to failure, there is an incredible release of energy which fuses the broken ends. The Dave Evans one does kinda look like heat from chafing was a factor. Bob(?) Adriance of Boat US was involved in quite a study after Hurricane Bob looking at the failed moorings in Padanaram Harbor. They attributed most of the failures to heat buildup in the chafing gear. Given a series of very large waves that passed through the harbor, I wonder if a violent tug simply snapped the mooring line where it angled through the bow chock. I'd like to see more research on that.