Most of us fish a sink tip on faith. You cast, you mend, you wait some vague number of seconds, and then the line comes tight and swings. What is actually happening down there is invisible, so we tend not to think about it very hard. In Episode 128, Eric Leininger walked through the mechanics of what a sink tip and fly are doing through a swing, and it reframed something I had been doing half-blind for years.
Your Rig Does Not Sink All at Once
The first thing worth internalizing is that your rig does not descend as a unit. Leininger describes the order of operations: the fly sinks first, followed by the leader, followed by the sink tip, followed by the Skagit head. Your system is strung out at an angle through the water column, not hanging straight down like a plumb bob.
That matters because the sink tip is often sinking sideways rather than straight, and as it comes under tension it accelerates the fly downriver. The tension does not just stop the sink — it actively drags the fly along and, depending on how much slack and angle you have, can yank it out of the zone you spent all that time getting it into.
Why the Fly Comes Back Up
Here is the part that explains a lot of fishless swings. When the line comes fully tight, the whole sink tip straightens out — and the fly actually rises toward the surface. You did the work of getting deep, and then the physics of tension undid it right as the fly entered the sweet spot.
Leininger's fix is a rod-tip move: pull the rod toward you to straighten out the kick in the tip before it loads up on its own. Taking that slack and angle out on your terms, early, means the tip is already aligned when tension arrives. The fly holds its depth through the swing instead of climbing out of it.
The flip side is that this rise is not always your enemy. A fly that lifts at the right moment in front of a fish is a trigger — that is the whole logic behind the classic swing. The point is to know which one you are doing. Right now, most of us are getting the lift by accident, at a random spot in the swing, rather than choosing where it happens.
Count Your Tip Down Like You Mean It
The other habit worth stealing is treating the countdown as arithmetic instead of a vibe. Sink tips are rated in inches per second. If you are fishing a seven-inch-per-second tip and you give it a ten count, you have roughly seventy inches — a bit under six feet — of descent, assuming reasonably slack line and forgiving current.
That is an estimate, not a laser measurement. Current speed, line angle, and fly weight all push it around. But the difference between "ten times seven, call it six feet" and "I counted to ten because that felt right" is the difference between adjusting deliberately and guessing. When you are not finding fish, you can add a five count and know what you changed. When you hang bottom, you can subtract and know why.
Activation: Letting the Current Do the Work
Leininger uses the phrase "activating that fly," and it is a good one. The moment the fly comes under tension, the current blows over the marabou and rabbit and the materials come alive — breathing, pulsing, opening and closing. A weighted fly hanging slack in the current is a dead object. The same fly under tension is a swimming thing.
Which is why heavily weighted patterns and swung presentations can work against each other. Something loaded with tungsten will plummet, but it also fights the tension that makes soft materials move. There is a balance point between getting down and staying alive, and it is worth thinking about that trade-off when you pick a fly rather than defaulting to the heaviest thing in the box.
Leininger also mentioned he builds his own leaders, stepping down 30 to 25 to 20 in a short seven-and-a-half-foot package for this kind of fishing. Short and stout turns a heavy fly over and keeps the whole system tracking together instead of hinging.
What to Change Tomorrow
Three things. Know the sink rate of the tip you are fishing and actually multiply it by your count. Pull the rod toward you to straighten the kick before the line loads on its own, so the fly holds depth through the swing. And when you tie or choose a fly, ask whether it will still breathe once the current gets on it, or whether you have built a sinker with feathers glued to it.
One more thing from the episode that has nothing to do with physics: Leininger made the point that you should listen to your guide, but also listen to the water — use your eyes and ears to work out what you did wrong, then fix it on the next cast. The swing is a slow game with a lot of repetitions. The anglers who improve are the ones treating each cast as information.
Gear
The honest answer is that the thing that helps most here is not something we sell — it is knowing the labeled sink rate of your specific tips, which is printed on the packaging and free. If you are building your own leaders like Leininger does, our Tips and Tricks for Fly Fishing ebook covers leader construction and the knots that hold up under heavy flies and hard tension.
For sink tips themselves, grain windows, and matching a Skagit head to your rod, go talk to your local fly shop. Getting that balance right depends on your specific rod and river, and a shop that knows your water will steer you better than any product page can.
