John,

The best way I've found is to melt the end with a liter then while the nylon (inside and out) is still hot use your fingers (with a little spit) to shape the end. This does two things a) seals the cord and b) anchors the core inside the kermantle so that you are always using all of the cord's strength. Be careful using a hot knife you may seal the kermantle, but leave the core untouched and thus unanchored. The core can slip through the kermantle in tension and leave you holding that expesive carbon fiber paddle to your deck with not much more than a thread

Matt