Page 13 - Joseph B. Healy "The Pocket Guide to Fishing Knots"

“But the confusion and lack of understanding of the importance of
knots was something we had to wade through back then, and I found a
couple things: You needed to attach a butt section to a fly line, and that
led to tying a Nail Knot, which is basically the same as a Uni-Knot or
Duncan Loop. The Nail Knot was as important back then as now,
although you didn’t have to tie it often. If you tied a good, eight-turn Nail
Knot and used no more than the twenty-pound (ten kilogram) maximum

tippet according to the rules of fly fishing, you weren’t going to have any
problems with it coming loose. It was pretty fail-safe. About twenty years
ago, we learned to tie the same knot without the nail and the Nail-less
Nail Knot was developed, thus destroying a micro industry because
nobody needed all those Nail Knot tools anymore. Of course, we always

used a paperclip for our Nail Knots.
“The other thing a Nail Knot allows you to do is to put a loop in the end
of your fly line. You can use two Nail Knots with fifteen-pound mono and
a little space between them to make a loop for connecting your fly line to
your backing. That’s a no-fail system. The Nail Knot is versatile in that