Named for the famous fly fisherman, George Harvey, the Harvey Dry Fly Knot is best used for connecting up or down hook eye flies to your tippet. It is a very small knot that is easy to tie. Once tied, it will pull the fly in a straight line, which is very important for fly fishing with certain flies. It should not be used on straight eye hooks, as it does not allow the fly to move side to side. The knot can also be used when fishing with nymphs.
In order to tie the Harvey Dry Fly Knot:
First insert the line end into the up or down turned hook eye. Pull the line through so that you have about 4 inches of line through the hook eye.
Make the loops large enough to work with, and grasp.
Once you have the two loops, run the tag line through the loops twice, making two wraps through the loops. You can hold the two loops with one of your hands, but be sure not to pass the line over the standing line.
You should now be able to pull the leading line tight. The Harvey dry fly knot should now cinch around the hook eye, thus not allowing it to move from side to side. If the coils do not cinch over the hook eye, you might have made a mistake in tying the knot. You can now trim the excess ends from the knot.