Tom Rowland | Nail Knot with a Lock - Tie it! Test it!! | Tom Rowland Podcast Ep. 886

Tom Rowland, host of the Tom Rowland Podcast, demonstrates how to tie a nail knot with a lock for fly fishing connections on this week's How 2 Tuesday episode. When fighting big fish like tarpon, a standard nail knot can slip under pressure, but the locked version adds security—though it comes with tradeoffs. In this tutorial, Tom walks through the step-by-step process using 50 pound J fluoro leader and an 11 weight fly line, then puts the connection to the test to see exactly how much force it can handle. The results reveal an interesting dilemma between knot strength and guide clearance that every serious fly angler needs to understand. Whether you're targeting tarpon in the Keys or heading offshore, the connection between your fly line and leader can make or break your shot at landing a fish of a lifetime.

The Problem with Welded Loops and Loop-to-Loop Connections

Most modern fly lines come with a welded loop already installed at the end, which creates a smooth, clean finish. Tom explains that while this manufacturer's loop is perfectly smooth and works great, the traditional solution—tying a double overhand loop in your leader and connecting loop-to-loop—creates an issue. Even with the tag end parallel to the running line rather than at a right angle like a perfection loop, these connections can catch in the rod guides when you're stripping line in or casting. For anglers targeting big fish who need to get the leader in and out of the guides quickly and smoothly, that little hang-up can cost you the fish. The nail knot with a lock offers an alternative that slides through guides more easily, but as Tom discovers in his testing, it comes with its own compromise. The full guide comparison starts at 2:30.

Choosing the Right Leader Material and Diameter

Before Tom even begins tying the knot, he addresses a question many fly anglers struggle with: what pound test should you use for the butt section of your leader? Working with an 11 weight fly line, Tom selects 50 pound J fluoro, explaining that while there's no set rule for exact pound test, you want the leader butt section to be similar in both diameter and stiffness to your fly line. This matching ensures a smooth transfer of energy during the cast, which is critical for turning over the fly properly. The goal is to create a tapered system that flows naturally from the heavy fly line down to your tippet and fly. It's one of those details that seems small but makes a huge difference in presentation, especially when you're throwing big flies at selective fish. Tom's material selection reasoning starts at 3:49.

The Tie Fast Knot Tyer Technique

What makes Tom's approach particularly clever is his use of a simple Tie Fast knot tyer tool that streamlines the entire process. Instead of wrestling with the fly line while trying to wrap the leader around it, Tom demonstrates how you can pre-build the entire nail knot structure before ever touching the fly line. He places the 50 pound fluoro into the gap on the tool, holds it with his thumb, then wraps back toward his thumb six to nine times. Once the wraps are complete, he threads the tag end back through the whole knot while it's still on the tool, then simply slides the fly line through and eases the pre-formed knot off the tyer. It's an elegant solution that takes the frustration out of a traditionally fiddly knot. But the nail knot alone isn't enough for big fish applications, which is where the lock becomes essential. The complete tying sequence starts at 4:18.

Adding the Figure Eight Lock

Once the nail knot is formed on the fly line, Tom intentionally doesn't cinch it down completely—he leaves it slightly loose with extra line extending past the knot. This is where the lock comes in. Tom ties a figure eight knot around the fly line just behind the nail knot, going around and behind twice before threading through to form the figure eight pattern. The key detail here is that Tom purposefully doesn't pull the figure eight tight until it's positioned exactly where he wants it, snug against the nail knot. Some anglers use a simple overhand for the lock, but Tom switched to the figure eight years ago after having overhands come untied. Once everything is positioned correctly, he tightens the figure eight, then pulls on the running line without pulling the tag end to fully seat the nail knot. The result is a smooth, streamlined connection that won't slip, but the real question is how strong it actually is. The locking technique is demonstrated at 6:00.

The Breaking Point Test and the Strength vs. Smoothness Dilemma

Tom puts the completed nail knot with a lock to the test, and the results reveal the inherent tradeoff in fly line connections. The knot broke at 28.58 pounds, failing within the knot itself rather than at the fly line or in the unknotted leader. Tom describes this result as slightly disappointing, especially compared to the much stronger loop-to-loop connection using the manufacturer's welded loop. However, he's quick to point out that 28 pounds is still more force than you'd typically exert on a tarpon or most other species during a fight. The real decision comes down to this: do you prioritize absolute strength with the loop-to-loop system that can catch in guides, or do you accept slightly lower breaking strength in exchange for a smoother connection that moves through guides cleanly? Tom acknowledges this is the dilemma, and there's no single right answer—it depends on your specific setup and fishing situation. The test results and full analysis start at 8:01.

Final Thoughts from Tom

I tie a lot of knots and test them so you don't have to guess when you're on the water. The nail knot with a lock is one of those connections where the numbers tell part of the story, but your specific fishing situation tells the rest. If you're constantly bringing that leader in and out of the guides—like when you're sight fishing for tarpon and need to make quick adjustments—that smooth connection might be worth more to you than a few extra pounds of breaking strength.

The figure eight lock is crucial. I learned that lesson the hard way years ago when simple overhands came untied on me. It's a small detail that makes a big difference when you've got a hundred-pound fish on the other end. And using that Tie Fast tool just makes the whole process cleaner and faster—no more fumbling around trying to wrap leader around fly line.

We've put together a complete knot guide with all the test results from these tutorials, and it's free at tomrowlandpodcast.com. You can see how different knots perform and make the right choice for your setup. This episode walks through every step, and if you're serious about fly fishing for big fish, it's worth watching the whole thing to see exactly how it's done.