The Davy knot was invented by Davy Wotton. It’s easy to tie, very strong, wastes little tippet material and, perhaps most importantly, is extremely small. You can see here how the improved clinch knot on the top absolutely dwarves the Davy knot below. This makes the Davy knot especially valuable when you’re tying on small flies to be used on finicky trout.
To tie the Davy knot, hold the hook in your left hand in an upright position and feed the line down through the eye. Bring the tag end over top of and around the running line and then back over top of itself. Then bring the tip of the tag up through the loop and get hold of it with the thumb and index finger of your left hand. This is the shape you’re looking for, sort of a modified figure 8.
Now, begin to draw the knot tight by pulling on the running line, all the while holding onto the tag. Oftentimes you will end up with something that looks like this, which is ok but a simple adjustment will keep the knot from slipping and make it a good bit stronger. Notice how the tag points slightly rearward and is positioned under the eye. What’s works better is having the tag contact the front of the eye and point outward at a 90 degree angle to the running line. This can be made to happen as you’re drawing the knot closed. It’s that 90 degree angle that’s the tell tale sign of a well-seated Davy knot.
It’s hard to believe such a small and simple knot could be so strong and reliable.
Here’s what it looks like with 15 pound test mono tied on a size 14 Hare’s Ear Nymph. Again, run the line top down through the eye and then cross over and around the running line. Bring the tag back over itself and then push it up through the loop, grabbing it with the thumb and index finger of your left hand as it exits. Draw the figure 8 shape closed by pulling on the running line and when you seat it, try to get that tag pointed out at a 90 degree angle. You can then reach in with nippers and cut the tag off close.
I found a tricky little way to tie a Davy knot using plunger-style hackle pliers. After passing the line through the hook eye, get hold of the very tag end with the hackle pliers. Follow the same path as before but do it with just the stem of the pliers. Once you get hold of the tip, release the pliers and pull them back out through the knot, then seat the knot as usual. With mono, it looks like this.
With a little practice, you should find the hackle pliers really increase the speed with which you can tie the knot. I keep my hackle pliers ringed to my nippers at the end of a zinger so everything I need is readily available. The hackle plier trick comes in especially handy with the real small stuff, here 7X tippet used to tie on a size 22 Parachute Adams. Oftentimes the hardest part is locating the tag end to snip it off.
Up close you can really see how small and unobtrusive the knot is.
The Davy knot works best with flies size 18 and under. For larger flies, a double Davy knot adds a good bit more strength but is also slightly bulkier. It's tied the same as the Davy knot but, after you exit the loop, go around the top leg of the loop once again with the tag before seating the knot as usual. This 15 pound test is a little too big for this fly but normal size tippet, say 4, 5 or 6X, seats really well with a Double Davy. Just in case you were wondering, the Double Davy can also be tied rather quickly using the hackle plier trick.
Although it took a while for me to get used to it, I’m now completely sold on both the Davy and the Double Davy. They’re both exceptional knots.