The Castwell Knot is simple and effective. And it uses a very small piece of your fly line to tie, which means if you change your leader, you will sacrifice only a quarter inch or so of fly line doing so.

Follow the link for instructions on how to tie it.

http://www.flyanglersonline.com/begi...s/castwell.php

John

P.S. And it's cheaper than buying a Tie-Fast tool. Which are cool, by the way. And useful for a lot of things.