Some fly fishers love the nail knot because they believe it creates better energy transfer from the fly line to the leader, although it is the weakest of the three connections (with trout fishing that’s rarely an issue as the tippet is the weakest part). You can also use the nail knot to attach the fly line backing to the fly line at the other end.
Others love the convenience and speed of loop connections because they allow for quick and easy leader changes.
One point to note is increasingly fly lines are produced with welded loops at the end making a loop knot connection more convenient still.
If you want to use a nail knot with a fly line with a welded loop, you will need to snip it off. Believe it or not my cat recently bit the end off my favorite trout fishing fly line so I have switched to the nail knot connection on that one!
Method 1: The Nail Knot Leader Connection
It is relatively simple to tie although it does need a thin cyclindrical object to tie (hence the term nail knot). See the graphic and video below for detail instructions on tying the nail knot.
You can use a nail knot tool to create this knot – they come in pretty handy and we’ve reviewed the main ones here.
A couple of tips to remember – always wet the knot before drawing it up tight and be sure to draw up coils reasonably tight before removing the nail.
The main advantage of the Nail Knot is that it is very thin and passes through the guides of your fly rod easily, especially when coated with UV glue.
As I mentioned, some people favor the Nail Knot because they believe the loop connection creates a hinge and doesn’t roll out the leader as well. I have never had that problem and don’t see that as a huge advantage of the Nail Knot.
The other downside to the Nail Knot is when you change leaders, unless you are careful you can nick the end of the fly line when you cut the coils of nylon off, which means you then have to snip off that small section of fly line and gradually you’ll be shortening your line over time and changing the profile. However, fly lines tend to wear out anyway before this becomes a serious issue.
Nail Knot Instructions
Nail Knot Video
Method 2: The Fly Line Loop to loop connection
As I mentioned, most fly lines these come with a welded loop. And if there is not welded loop, it is easy enough to create a loop with braid. Properly constructed braided loops will hold up for years, especially if sealed with UV glue.
If you leader comes with a pre-made loop (as many do these days) then the connection is easy: just slide the leader loop over the top of the fly line loop (sliding it up the line) and pass the free end of the leader through the fly and pull it all the way through. When you tighten it up the two loops will nestle snugly together and you have a solid loop to loop connection.
To create the loop, I like to use a Figure of Eight loop knot. It is simple and relays 100% of the strength and, importantly, the tag faces backwards, which helps it slide through the guides.
Figure 8 Loop Knot Instructions
Method 3: Albright Knot Connection
The Albright Knot is the strongest way to join the fly line to the leader. With this fishing knot you make your own loop in the fly line and then make a series of wraps with the nylon pinching the loop. Instructions are below. This is a simple knot to tie and very strong – as always lubricate the knot before you pull it tight.
The tags on the two lines tend to lie flat making the Albright knot quite a slim profile connection from the point of view of sliding through the rod guides.
The main disadvantage of it is the same as the nail knot – if you aren’t really careful about snipping off the coils when you change leaders you will wind up damaging the end of the fly line and having to snip that part off.
Hybrid Approach using a Nail Knot and Loop Knot
One final method to mention is a hybrid of both of these techniques. This is a way to get the energy transfer benefit of a nail knot without sacrificing fly line and losing time with leader changes. It involves using a short (three inches) connecting section of mono of similar diameter of the butt end of the leader.
You connect this with a nail knot and then tie a loop in the other end using the figure eight loop, improved loop knot or perfection loop.
That then becomes the loop for loop to loop connections.