Leader Design - Saltwater and Freshwater

[CaryGreene]

I’m putting this thread together at the request of a few folks and I even have a number of friends on the site who have asked previously for me to get this info up. Many advanced anglers have tried some of the concepts as I’ve advocated and their already excellent casting and results got even better. They tried because they were curious. Perhaps they are driven to always improve. As Einstein said, “The more I learn, the more I realize how much I don’t know.” Does a proper Leader make you cast better? 

 

I’ll stop short of saying that, because from an aerodynamics point of view, as airplanes don’t fly themselves and without being put into motion, they couldn’t get off the ground. But every single square inch of an airplane determines its flight characteristics, of that I’m sure. The same is true of a Fly-Line, a Leader and a Fly. 

 

Small tweaks here and there with our Fly-Lines, our Leaders or the Knots we use can make already perfectly good results even better. They can absolutely impact the end result >> actual fishing. They can also make the experiences we have while fishing a little bit more fun than they already are! When we’re casting well enough to do the job and a proper Leader is making results better with every single cast, its a wonder that fly-casters don’t spend more time thinking about their Leaders and tending to them. But, most don’t. Leaders are by far the most neglected piece of most fly-casters approaches and paraphernalia. Most fly fishermen pay more attention to the flash in their fly or their polarized sunglasses than they do their Leader. 

 

This thread is therefore for everyone, from beginner level to those more advanced, to dare I say - “expert” level fishermen. 

 

The purpose of this thread isn’t for me to “teach anyone opposed to learning new things.” If you haven’t already inferred by my comments above, my journey in fly-fishing is ever evolving. I’m always learning new things and trying new ways to do things that might be an improvement. If you’re not, that’s perfectly cool!

 

This thread is a place to share information with the goal of making time on the water more fun. Therefore, if you already have plenty of fun on the water and you’re getting results you’re satisfied with and if you feel you don’t need to improve, then why participate in the thread?

 

Someone might make a helpful suggestion, but if the person receiving the suggestion doesn’t feel they need any help, then they likely will keep doing whatever it is they’re doing. No one will mind, least of all me. 

 

I Saw a Man Pursuing the Horizon

By Stephen Crane

I saw a man pursuing the horizon; 

Round and round they sped. 

I was distrubed at this;

I accosted the man

“It is futile,” I said,

“You can never–”

“You lie,” he cried,

And ran on.

 

The thread is dedicated to Leader Design for Spin/Conventional Surf Casters and Freshwater/Saltwater Fly-Fishing. 

 

The post will grow and become enhanced by member participation so what I know or say will easily be eclipsed by the sum of our collective comments and knowledge. There will be a great many debates as we go along for sure, of this I’m sure. Casting and Leaders are intertwined and they always will be. We often change our casting when using certain Leaders because Leaders are used to match situations. Therefore, I’m sure there will be a great deal of casting conversation in this thread because we couldn’t have a Leader thread without it. 

 

Each post I put up in time will be for specific applications. I’m going to kick the thread off by starting with recent requests for Saltwater Fly-Fishing Leader Design Info. Saltwater Fly-Fishing is a specialty activity in which casters throw all sorts of various flies at a staggering number of Saltwater species. 

 

Sometimes a caster is almost waist deep in the wash out-front and dealing with wind and waves and constantly changing footing (ever notice how you have to constantly step up out of the sand to higher ground, from the divot that forms around you fairly quickly, when you’re in the wash?). Other times the caster may be perched on a boulder, a dock or along a jetty and still other times, the caster might be casting from the deck of a skiff or a larger boat. Fly-casters often deal with wind and wind can come from any and all directions. 

 

Saltwater fly-casting is very much related to freshwater streamer fishing, which is done both in rivers (which have current moving from one direction to another) and on ponds or lakes. Sometimes freshwater streamer fisherman “troll” flies from a very slow moving or drifting boat. Other times, they may cast into a pond or lake from a stationary position with ample room for a back-cast - or no room at all (in which case they roll-cast the day away). In fact, we use the basic roll-cast in Saltwater fishing often, to help us get a line airborne. 

 

Sometimes fly-casters want to generate high-line-speed and nice tight loops and at other times, they might want a much more open loop and slower line speed and sometimes, they don’t want a loop at all. 

 

For example, when we’re dry fly-fishing, we may want to speed the line up quickly to dry a fly off from the soaking it took on a previous drift, aiming the cast in quite a different vicinity than a rising fish we are targeting may be in, and then we might slow the cast down and change direction towards the target to delicately present the fly with tremendous accuracy. This means that during a cast, we might create a series of quick, short, tight loops and then, we might extend the amount of line we have in the air and very deliberately open the loop significantly, to create a smooth presentation where the line, once straightened in mid air, is actually pulled backwards abruptly, causing the leader to fall in a series of "S-Curves.”

 

With most saltwater casts, our objective is to deliver a fly with higher line speed but there are times when fish are very close to us and line speed isn’t that important. We often cast off-the-tip of the rod when making a quick, short cast and even a very stiff rod is often able to do an okay job of this. 

 

However, when we begin casting at mid-range distances of 30 feet to 80 feet, higher line speed is needed to make the cast. It’s also very nice to be able to generate the line speed quickly and “turnover” becomes quite important because we’d like the line and the leader to lay out in a “slackless” presentation. 

 

Trout anglers often build leaders to create slack, which helps absorb drag created by swirling currents in a river. >> This helps the angler achieve more drag-free-drifts. Exceptionally good performing freshwater leaders are made with Butt-Sections that are stiff and more supple material is often used to create the Mid-Sections and Tippets. The benefit to doing this is that a supple Mid-Section and Tippet can absorb Drag caused by water. This allows for Drag-Free drifts. If a Leader were too stiff, it wouldn’t move easily when swirling-currents push against it and therefore, the fly will “skate” across the surface, behaving in an unnatural way. 

 

Soft, supple material on the other hand, moves when the swirling-currents push against it >> but the fly remains still for longer as the soft, supple leader absorbs the Drag caused by the currents. 

 

In Saltwater fishing, we want exactly the opposite to occur. >> We want a ruler-straight presentation without slack and one that’s right on target, so when we start stripping line, we immediately also start moving the fly the way we intend. 

 

Saltwater Leaders don’t need to be very technical. >> A school of thought has persisted for years among many saltwater fly-fishermen, that it’s not necessary to get overly technical with saltwater leaders and I agree. Saltwater leaders aren’t technical at all. They’re simple three-piece "doohickies” that deliver flies that can be pretty big at times to a target and they should absolutely have characteristics that turn wind-resistant flies over easily and cause them to straighten out easily, ahead of the tip of the fly-line. If this doesn’t happen then results suffer. We shouldn’t over-think them - for sure! But we also shouldn’t under-think them because if we do, results suffer badly. 

 

Using the right leader is actually super easy and it’s also very affordable. >> It will be the least expensive part of your investment in fly-fishing tackle so these are two good reasons to ensure you’ve got the bases covered. 

 

Casting practice is very important - even vital, but if you practice until you fall over dead, if your line and Leader setup is working against you, your outcome can be dramatically impared. When you fish constantly and spend time in various conditions on an almost daily basis, this becomes very obvious. The Leader should help the caster, not hinder them.

 

Fly-casters select the size of the rod based on the fish they’re targeting but also, it can help deliver the flies they’re going to be using too. >> The fly-line also plays a huge part in this endeavor and the leader helps tremendously as well. When fly-casters go to bigger and heavier flies, it’s always a good idea to move up to a heavier fly rod outfitted with a beefier fly-line. 

 

For example, tossing heavily weighted crab patterns to tailing Permit on a 7wt rod isn’t very comfortable or effective. Heavier, more wind-resistant flies create a lot of Drag. But a heavier fly line like, a 10wt, gives the caster more mass and more power to roll that heavy crab fly straight out and that allows them to cast very accurately - which is a big benefit because now, they can cast from further away from the fish and this means ultimately, the fish has less of a chance of getting spooked. 

 

Leaders work the same way and similarly to the fly-line, the more diameter or mass that’s in the leader’s Butt-Section and Mid-Section, the greater its ability is to transfer more energy. A properly constructed leader loses much less energy than one that’s too thin. 

 

Constructing a proper Saltwater Leader involves knowing the diameter of the tip of your fly-line. >> A digital micrometer is the best way to get an accurate reading. Once we know the measurement, we can construct a proper Saltwater Leader very easily. The goal is to very nearly match the Butt-Section of our Leader with Tip of the Fly-Line. We want the Leader-Butt to be approximately .010” thinner. 

 

 

If we ignore this concept and use a material that is too thin, the Leader can hinge or even collapse and it’s very difficult to notice this happening at distances beyond even 30 feet. This happens because the Butt-Section lets too much of the energy coming from the tip of the fly line dissipate, instead of capturing a far greater amount of this energy and being able to transfer it to the Mid Section of the Leader. 

 

Once all that energy that a well designed Leader-Butt captured and successfully transferred to the Mid-Section, the cast is all but complete. A short length of Tippet will easily be moved by it and the fly will miraculously turn over and straighten out. A good cast even pulls once it straightens out in the air. 

 

My general observations on fly-line “Tip-Diameters over the Years. >> Most Fly-LInes that I’ve used - from line-manufacturers like Airflo, Scientific Anglers, Rio Wulff and Cortland, will fall in the below categories, which you can use as a loose guide that is by no means always right. I find most 8wt to 12 wt lines will have Tips that measure between .040” and .050”

 

Leader Butt Diameter Needed to Match 8wt to 12wt Fly LInes

• 8wt’s are usually between .040” and .042” 

• 9wt lines will be in the .042” to .044” range

• 10wt lines will be .044” to .046” 

• 11wt lines will be .046” to .048” 

• 12wt  lines will fall more in the .048” to .050” range. 

 

Regarding commercially made Leaders. >> Many manufacturers are now even hiding the Butt-Diameter of the Leader. For example, Rio doesn’t even list the Butt-Diamter of their “Saltwater Leader” on the package. They give you the Tip-Diameter though!? (no idea why we need that info). Fortunately some still post the info somewhere. Scientific Anglers posts it. 

 

95% of all commercially made Leaders aren’t very compatible with 8wt to 12wt lines as they’re also designed to be used with 5wt to 7wt lines. Will they work on the heavier line sizes? Not very well. Fly-casters often don’t notice this, because they have enough to worry about with the cast and the loop and the wind and the fly and the busting fish…etc. But give them a properly made Leader and they’ll notice the difference immediately. This is because the fly is now landing straight out in front of the line, instead of off to the side (which can cause wind knots in the Tippet). 

 

For example, here's a popular Rio Saltwater Leader. The Butt-Section Diamter isn't even listed anymore on the blasted package! - Though I was able to find it listed by a fly-shop who sells their products.

 

 

The Butt Diamter on all of their leaders is WAY too thin for 8wt to 12wt Saltwater Fly Lines and the resulting Turnover, which we'll get into shortly, is horrible. 

 

Now here's a Scientific Anglers commercially made Leader. Same problem. Won't work well for Saltwater Lines. The reason for these problems is that the Leaders are also used by Steelhead and Salmon anglers and they may favor 6wt or 7wt rods/lines. Companies try to make sure their Leaders will work with a wide variety of Fly Rod Weights. 

 

 

Again, S-A is way too thin but, as I mentioned and this is a massive pet-peeve of mine, at least they actually POST their Leader Butt Diameters -- unlike Rio and many others these days. Not doing this is hard for me to even comprehend. Talk about dumming down your customer base!

 

Therefore, an easy fix is to add 18” of whatever diameter the Leader-Butt needs to be - to be .010” thinner than the Tip of your Fly-LIne. Doing this aids your Leader’s ability to “Turn-Over '' and provides a smooth transfer of energy from Fly-Line Tip to the Fly. 

 

Should a saltwater leader be made out of LIMP or STIFF material? >> Soft leader material is supple and it forms tighter loops because it’s easier to bend and it helps to introduce slack into the leader for “Drag-Free” Drifts, but soft material is less efficient at transferring energy to lay out a long leader with a heavy fly, straight into the wind. This is because air pushes against the leader as it tries to un-roll. 

 

Stiffer leader material better supports the weight of heavier flies while casting and it tends to lay out straight, with far less slack. In Saltwater fly-casting, stiffer is always better because it gives the fly-caster straight presentations. Its harder exterior is also more abrasion-resistant, which helps when dealing with a fish with a rough mouth or teeth and also, it helps tremendously when there’s Coral present or other rough surfaces like barnacle encrusted rocks or substrates that have mixed gravel bottoms. 

 

How many pieces should a proper Leader have? >> The answer to this question varies depending on the performance characteristics required by a given application. 

 

For example, Dry Fly Leaders may have many pieces. The more pieces a leader has, the more energy it loses as it unrolls. If the goal is to cause a very slow, deliberate, open casting- loop then we would use many sections to gradually transition from the Leader’s Butt section to its Tippet but the real reason for doing this is not to achieve such a loop. 

 

The open loop is a byproduct of constructing a Leader with many sections. The reason for doing this is to create a gradually tapering leader that is soft and supple and able to absorb drag when swirling currents in the water push against it. 

 

To compensate for the fairly poor casting characteristics of a Leader that is outstanding at absorbing Drag and creating “Slack,” the fly-caster slows the timing of the casting-stroke down, to allow extra time for this leader to turn over. 

 

Conversely, if the goal is to cast at distance, we want as few Leader sections as possible to do the job, which in Streamer fishing or Saltwater-casting, would always be three pieces. 

 

Thin, one-piece Leaders lose a ton of energy at the Tip-to-Leader connection point. This translates into terrible turnover. Upwards of 95% of the Fly-Line’s energy is lost by using a one-piece Leader that is too thin. Two piece Leaders consisting of a Tippet and a Butt-Section also lose way too much energy and they turn over poorly. 

 

However, a three-piece Leader with a long butt-section and a short mid-section actually holds the most energy as is possible and transmits this energy directly to the fly. 

 

Meanwhile, a four piece leader with two longer Mid-Sections loses twice as much energy in the Mid-Section as compared to the three piece leader. There is zero benefit for making a leader like this for Saltwater fly-casting. 

 

What is the best Saltwater Leader Length? >> The answer to this question depends on the size of the fly and ease in which you can turn the fly over with your cast. The goal is to fish comfortably and be as stealthy as possible when needed. Longer leaders are generally stealthier than shorter ones. Bulkier or heavier Flies tend to turn over better with shorter Leaders, in the 6’ to 7 ½’ range in length. Average sized Flies tend to turnover fine with 9’ to 10’ Leaders. 

 

What is the optimal Saltwater Leader formula to achieve a desired Leader-length? >> For normal sized Flies, Begin with a Butt-Diameter approximately .010 Thinner than the Tip of your Fly-Line. 60% of your leader should be made of whatever diameter this material winds up being. 

 

Then, 30% of your Leader should comprise the Mid-Section, which in turn should be as thick as possible to hold maximum energy while also providing a sharp taper to your Tippet. A general rule of thumb here is simply “halve” your Butt-Section and use a Mid-Section of that Diameter. For example, If you’re using a Butt Section that’s .040, your Mid-Section could be .025 or so. There’s no need to be on the thinner side of “half.” Air on the thicker side. 

 

Finally, your Tippet should be 10% of the Leader’s length, whatever Test# the situation calls for. The basic all-around formula is 60% - 30% - 10%. A very good caster who generates high-line speeds can even add a bonus 10% to the Tippet section, but be careful doing this because you can easily negate the benefit of the leader if the Tippet is more than say 20” long. 

 

For larger, bulky flies, the Leader formula can be tweaked even further to max- performance which can be 70% - 20% - 10%. 

 

What about Braided or “Furled” Leaders? >> In Freshwater river fishing applications, “Furled Leaders” made of Silk, or thread, or even Nylons have been hand-fashioned as a way of creating a more supple Leader-Butt section. Fly-casters attach sections of Monofilament or Fluorocarbon to these Furled (Braided) Leaders and they like the “Turnover Characteristics” of these Leaders with freshwater sized flies and their ability to help absorb Drag caused by swirling currents in the river. The surface of moving water moves at various speeds because of obstacles that protrude from the river bottom. 

 

Do these leaders really turnover better than my formula above? No. They don’t. What they do have is substantial diameter but is it .010” thinner than the tip of a given fly line? Possibly. But since most fly-casters use Leaders which feature Butt-Diameters that are too thin to begin with, it “seems like” the Furled leader turns over better. I assure you, it does not. Assuming it’s .010” thinner than the Tip of the Fly-LIne, it turns over no better than a leader made with my formula and it actually supports the mass of large fly worse than Medium-Hard to Hard material will, which actually makes them slightly worse at turning flies over. 

 

If a fly-caster is positioned in a particular spot in a river and is casting to another spot, or multiple spots as they cover the water, oftentimes the water in between where the fly-fisherman is standing and where he’s casting to can contain variable currents, some faster and some slower. If a “Drag-Free-Drift” is the goal, the Leader has to assist in absorbing those currents, otherwise the fly will move unnaturally. Furled Leaders are one way to accomplish this but unfortunately, unless they’re made of monofilament, they inherently sink, which makes most commercially Furled Leaders a bad choice for dry fly fishing. There are other drawbacks as well. 

 

If a Furled Leader has a long midsection and a long piece of Tippet, the fish may never see the floating fly pass on by and as long as the Furled leader is still floating, the durability characteristics are the big attraction with these types of Leaders. 

 

A massive drawback though is that Furled Leaders are 100% visible when fished sub surface, so they dramatically negatively impact your ability to present a subsurface fly stealthily. If you add too much nylon or Fluorocarbon, Leader Turnover also suffers dramatically. There is little benefit in using a Furled Leader for subsurface fishing. 

 

Another drawback is that Furled Leaders are worse for turning over larger, heavier Saltwater Flies than Leaders made of stiffer Monofilament or Fluorocarbon. This is because soft material cannot support the weight of larger Saltwater flies. 

 

Yet another drawback of a Furled Leader is that they absorb micro debris and become very heavy and start to sink. This is horrible for Dry-Fly Fishing as a leader with that much mass will drag a small Dry Fly pattern right under the water in no time. That’s why Dry Fly Leaders aren’t Furled. 

 

Lastly, a Furled Leader, no matter what its make out of, will trap water. This sprays on the forward cast and can cause a lot of surface disturbance on an otherwise glassy piece of water. 

 

Furled Leaders can be okay for fishing Nymphs but again, they actually aren’t particularly good at supporting and turning over significant weight, like Tungsten beads or lead shot, but - because they’re durable and easy to loop on and forget about, they have their place because their main benefit is really that they last a long time and resist knicks and cuts. Many like them for this reason, that they’re very low maintenance. 

 

What About “Poly Coated” Leaders? >> Poly Leaders are Polyurethane coated monofilament core Leaders that have very substantial Mass and Diameter. They’re also very soft and supple. Because of their Mass, their main benefit is Turnover and Durability. In freshwater streamer applications, they can be attractive, mainly because they’re durable and in some cases, they can be impregnated with tungsten powder so that they sink. This can help deliver a fly sub surface, on the swing, in moving current. Spey-fishermen sometimes use these types of Leaders. Spey casts are modified Roll-Casts which form exaggerated “D-Loops” and then launch towards the target without the need for false casting prior to shooting. 

 

The drawback to them for overhand streamer fishing and for Saltwater is that they hinge horribly when cast back and forth a few times prior to shooting line and again, they are 100% visible to the fish because their high index of refraction makes them stand out when compared to other materials like Monofilament or Fluorocarbon, so they aren’t viable for delivering flies in clear water at distance. This makes them a terrible choice for Saltwater fishing. 

 

Is Monofilament or Fluorocarbon better for Saltwater Fly-Fishing Leaders? >> Nylon (monofilament) is a copolymer that can come in different formulations. Most brands have a saltwater nylon formulation that is often referred to as “Hard” or “Medium Hard.” 

 

Fluorocarbon is by nature even stiffer and more abrasion-resistant than nylon. Put tension on a heavy piece of Monofilament and using an abrasive object such as a jagged rock, move the object quickly back and forth over the surface of the Monofilament. It doesn’t take long for the material to fray and be cut in half. Not repeat using Fluorocarbon, you’ll notice it always takes longer for the same thing to happen to the Fluorocarbon. However, Saltwater-Grade Hoard Monofilaments have very good abrasion resistance, much better than softer Monofilaments so IMHO the advantages that Fluorocarbon provides in this department is a bit over-blown. 

 

Both Fluorocarbon and Monofilament reflect sunlight, but Fluorocarbon is absolutely less visible when submerged in water because it’s “Index of Refraction” 1.46, compared to that of water which is 1.33. Monofilament on the other hand measures a 1.72 so there is no denying that in gin clear water, with sunlight present, Fluorocarbon has a bit of an advantage here. 

That said, Fluorocarbon isn’t always the best solution. Saltwater Leaders can be quite “beefy” when we consider their Butt-Sections and Mid-Sections and ones constructed with Fluorocarbon tend to sink quickly. This is great when dumping a fly into a rip out in the Race or near Plum Gut or whatever else you have ample water-depth. Generally I’ll use Fluorocarbon whenever I have around 10’ of water-depth. Fluorocarbon sinks because it has a Specific Gravity of 1.26, which is heavier than that of Water’s 1.0 - with Monofilament registering a 1.14 which is somewhere in the middle. People think Monofilament floats, but it really doesn’t, it just sinks really, really slowly!

 

Sometimes when casting to cruising Stripers on the flats, a fly can snag the bottom too easily with a Fluorocarbon Leader. This happens all the time when Bonefishing or casting to tailing Permit or Snook as well. Tarpon fishing is often done in shallower water in and around Mangroves and for all of these types of situations, Monofilament is by far a better material because the fly-caster requires “Neutral Buoyancy.” 

 

If I’m fishing water depths of less than 5’ of water I’ll generally use Saltwater Leader-Grade Monofilament of the Hard or Medium-Hard varietals. 

 

Which Materials Should You Use? >> My favorite materials to make Monofilament Saltwater Leaders from is made in the USA Scientific Anglers Absolute Hard Mono, mainly because it is a true medium hard, tough as nails copolymer that ties great knots and also because it comes in a suitable array of diameters (and corresponding # Test for building fly-fishing Leaders). 

S-A has all the bases covered with this stuff and it’s replaced my other favorite, the Japanese made Hatch Professional Series Med-Hard Mono - which also comes in a full size range and functions in much the same way as the S-A Absolute Hard Mono.

 

 

Are there other Monofilament materials I’d recommend? >>I like the made in the USA Rio Saltwater Mono but it’s not even made heavier than 60# (.030”) and because of this I don’t bother with it because many Fly-Line Tips require heavier Butt-Sections (especially 11wt to 14wt lines). The made in the USA KastKing Dura Blend is also “okay” but it isn’t made lighter than 20# (.019”) so again, I don’t bother with it. 

 

You could easily just use other manufacturers materials with these two materials to make complete Leaders but IMO - why bother? Scientific Anglers and Hatch have all the bases covered. 

 

What's so good about Scientific Anglers Absolute Hard Mono and Hatch Professional Series Med-Hard Mono? >> Both the Hatch and the Scientific Anglers materials are great for the shallows game. Most nylons get scraped and nicked when the bottom is a constant, real and present threat. Mussel beds can ruin softer materials easily and barnacle encrusted dock pilings and submerged parts of jetties can also do a serious number on leaders but these two materials are particularly good at holding up. 

 

I’ve also had very good results with it on Stripers around sharp rocks on the Rhode Island and Montauk shore-line and it’s great around erosion control structures, for mangrove Snappers hugging oil-rig structures. It even holds up well on 15lb to 20 lb Bluefish and other toothy predators like Alligator Gar and Barracuda.

 

All of these Monofilament Leader-Materials I’m calling out are hard/stiff nylon polymer leaders which lay out straighter than limper material, so fly-casting with this stuff makes it easy to keep in contact with the fly when you start the retrieve and unlike fluorocarbon, it has almost neutral density, so you won't be raking the bottom. 

 

What’s cool about all of these materials is that, while It's easy to be "stiff" with oversize diameters, these four materials are true to diameter (I tested each of them), they knot easily and they’re all battle-tested. 

 

Are there other brands you could use to save money? >> Absolutely. Probably one of the most cost effective Leader-materials out there is the made in the USA Berkley Trilene Big Game and a lot of spin and conventional surf casters have been using and liking their results with this stuff for years. It’s got decent abrasion resistance but it’s a little softer than the other four materials I’ve recommended. Is it better than KastKing DuraBlend? No, because it’s not as stiff. Therefore, Trilene Big Game won’t lay out as straight as the others I’ve recommended will. 

 

 

What role does a Leader Play in a Cast? >> In a Saltwater-cast, Leaders support the Mass of a Fly and they turn the fly over and lay it out straight. In Freshwater casts, they do this as well, but they may be specifically made to be prone to landing in “S-Curves” (as with Dry Fly and Emerger fishing) or in some cases, to not support the weight of the fly at all (as with Tuck casts). 

 

How does a fly-cast really work and how does a Leader really function? >> All fly-casters begin by  imparting “Motion” to the fly line using a “Simple Lever” – the rod and also a “Complex Lever” – the human body. The fly-line is able to elevate off the ground thanks to motion and from there, its all about basic Aerodynamics 101 class as “Lift” is generated by the difference in velocity of the Line (a solid object) and the air (a fluid). Once the fly-line is started into motion the motion between the air makes it possible for the fly line to be cast and stay in the air. 

 

It makes no difference at all whether the object moves through a static fluid, or whether the fluid moves past a static solid object. Lift acts perpendicular to the motion and this is why softer Leaders form tighter loops, because air pushes on them during the cast and the material bends more easily. The harder material doesn’t bend as easily, but it supports the mass (weight) of the flies and even though the air is pushing against the larger, less aerodynamic flies, the Leader turns them over far better. This is why we like medium-hard Leader-Material for Saltwater Leaders, where Leader Turnover at distance is of paramount importance. 

 

Air moves past the fly line and that Lift acts perpendicular to the motion is because a force called “Drag” acts in the direction opposed to the motion. Drag is an aerodynamic force that is also present in a fly-cast or any other type of flight for that matter. Drag opposes the fly-lines motion through the air and it is also generated by the mass of the fly line head, the leader and in Saltwater Fly-Fishing, the fly can add a tremendous amount of Drag to a cast as well (usually much more than the Line or Leader does).

 

Besides needing enough momentum to allow a Leader to turn a wind resistant Saltwater fly over and lay out straight, we need to conserve as much of the fly line’s momentum (energy) as is possible, especially when the loop eventually slows down, due to Drag. It’s important to understand that like all mechanical forces, drag must be generated in order to occur. 

Drag is created in a fly cast by the interaction with and the contact of the line, the leader and especially the fly >> with the air. 

That’s why casts start by speeding up, then they begin to slow down, until they stop >> at which point the fly line is laid out in a straight line, in mid-air. 

 

For Drag to be generated,  the solid fly line and leader must be in contact with the air. Without air, we couldn’t cast a fly line and without air, a plane couldn’t fly unless it used some other force entirely (which is actually theoretically possible). 

The difference between the speed or “velocity” of the fly line and the air causes Drag to be generated. If the fly line isn’t moving, there can be no drag. In casting as with any object in “flight,” Drag is a force and it therefore becomes a “Vector Quantity” - one that has both a “Magnitude” and a “Direction.” Some Vector Quantities only have “Magnitude” and these are called Scalar Quantities. 

 

We live in a four-dimensional world as far as we know (there could be other dimensions but they may have little to do with fly-casting) which is governed by the passing of time and three space dimensions; up and down, left and right, and back and forth. 

 

We observe that there are some quantities and processes in our world that depend on the “direction” in which they occur, and there are some quantities that don’t at all. For example, the volume of an object doesn’t require direction. Using a saltwater fly box for an example, the three-dimensional space that the box occupies has nothing to do with direction. If we throw it on the beach in one direction and then throw it on the beach in another direction, the fly box still has the same mass. Since the mass of the fly box doesn’t change no matter where we move it, we call this a “Scalar Quantity.” 

 

Flies are Scalar also. They don’t change when they are moved back and forth prior to shooting a cast. But their location changes from point to point in much the same way that, if we move the box to the east end of the beach, a mile away and put it on a rock, then we move it to the west end of the beach and were to lay it in the sand. In both cases, the resulting location of the physical object, the fly and the box, changes very much, so we call a quantity that depends on location a “Vector Quantity.” 

 

Obviously fly-casting involves Vector Quantities because we are moving the physical object, the Fly Line, the Leader and the Fly - towards the target in one direction, then we’re pulling it away from the target 180 degrees in the opposite direction. Any time you deal with Vectors, things get a little bit more complicated than Scalars. 

 

When we look at basic forces that are used to make a cast, we use Vector Quantities, such as the mass of the castable portion of the head of the fly line and the mass of the leader, the friction on the guides, the thrust that’s moving the line and other aerodynamic forces – all of them are vectors. 

 

Then we look at the resulting motion of the line in terms of how much air it displaces, its velocity and its changes in acceleration and it slows down and speeds up during a cast. These things are also all Vectors and they can be determined by the application of Newton’s laws for Vectors. 

 

Mass and Weight can also get confusing when it pertains to flight and likewise, as related to fly-casting. Weight is a force which is a Vector because it has a magnitude and a direction. Though Weight and Mass are related to one another, they are absolutely different quantities. Mass is Scalar. 

 

While Newton's laws describe the resulting motion of a solid, there are special equations which describe the motion of fluids, gasses and liquids. In fly-casting, as is true with any physical system, the Mass, Momentum and Energy of the system must be conserved.

 

Mass and energy are scalar quantities, while Momentum is a Vector Quantity. All three quantities are factors involved in fly casting. We would use the Navier-Stokes equations to understand how the air (a fluid) reacts to the fly line & leader and the reason this is important in casting is because the NS equations are the flud equivalent of Newton’s laws of motion. 

 

For people who spend inordinate amounts of time practicing casting out on the lawn or at the park, without substantial Saltwater Flies tied onto their Leaders, Leader turnover is but an afterthought. But for those of us who actually fish a lot, it’s the single most important part of our cast - regardless of the distance we’re able to achieve (or not achieve). If we can’t turn the fly over well, our results definitely suffer. 

 

What is Drag as it pertains to a cast? >> This brings us back to Drag and why Drag is so important to offset/overcome in Fly Casting. Drag acts in a direction that is opposite to the motion of the fly line (or any flying object). 

Lift acts perpendicular to the motion. There are many factors that affect the Magnitude of the Drag. Many factors also affect Lift but there are some factors that are unique to a Fly Line’s Drag. 

 

When a Fly-Line, a Leader and bulky Fly move  through the air, the air resists their motion and pushes into the Casting-Loop and against the Fly, which basically subjects the line to an aerodynamic force in a direction opposed to the motion. This is what Drag is and why it’s important to a cast. The Cast is moving towards a target but unseen forces are pushing against the cast. 

 

Lift has many factors that affect Drag. Some can be grouped into those associated with the Fly-Line and Leader, some have to do with the motion of the line through the air and then there’s the air itself which plays a role. 

 

Geometry has a big effect on how much drag is generated by the castable portion of the head of a fly line and this is a big reason leaders are super important in distance casting. Drag depends linearly on the size of the fly-line moving through the air. 

 

Why are Fly-Lines made with “Slick” coatings? >> Slick coatings allow running lines to shoot further due to reduced abrasion when moving through the guides. But manufacturers don’t just coat running lines, they make the entire fly line slick because they too move through the guides. Manufacturers also make fly lines hard and smooth, sometimes with almost imperceptible textures that give them more surface area which in turn helps them float.

 

Sinking fly lines are never textured, there is no need. The cross-sectional shape of the fly line determines what is called the “form drag” which is created by the pressure variation around the casting loop and even the line behind this loop. The three dimensional shape of the fly-line and leader affects the amount of drag that the line & leader induce. Smooth, non porous lines produce less drag than textured lines (but they tend to float worse). This is actually called “Skin Friction” which is always included in the measured drag coefficient when fly line manufacturers design a Fly-Line.

 

Since Drag is associated with the movement of the fly line through the air, this means drag depends on the “Velocity” of the air. Like Lift, Drag varies with the square of the relative velocity between the line and the air. The inclination of the Fly-Line to the flow affects the amount of drag the Line, the Leader and the Fly generate. As the casting loop moves in one direction or another, the loop is inclined to the flight direction at an angle and the “Angle of Attack” is created, which has a huge effect on the Drag generated by the Line, the Leader and the Fly.  The magnitude of the drag generated by a fly line depends on the shape of the loop and how it moves. 

 

As casting loops unfurl, the drag rises quickly because of increased frontal area and increased boundary layer thickness. As the line moves, believe it or not, air molecules actually stick to it’s surface. This creates the boundary layer which changes the shape of the loop. The flow reacts to the advancing loop. 

 

When casting loops are compact and properly formed, drag is nearly constant. Once the loop begins to stall, it can become highly unsteady and the value of drag becomes much greater. This means that a bulky fly can become a real problem.A properly designed leader works in conjunction with the taper of the front taper of the fly line and this helps to to keep the loop from stalling for as long as possible, because a properly designed leader that is thick enough, will transmit a big percentage of the energy from a stalling loop directly to the fly. 

 

Drag depends directly on the mass of flow going past the moving fly line and it also depends on the air’s viscosity and compressibility. With all things that fly, the information gathered regarding the factors that affect drag can be built into a “Drag Equation” that can predict how much drag force is generated by a casting-loop, or any other fly object, at a given speed through the air. 

 

We can think of drag as aerodynamic friction and one of the sources of drag is skin friction between the molecules of air and the surface of the fly line. Because the skin friction is an interaction between a solid - the fly line and a gas, the air, the magnitude of the skin friction depends on properties of both the line and the air. 

 

The smoother the line’s surface, the less friction there is. “Slickness” is great for shooting running line but it helps a fly line knife through the air as well, creating less drag. Meanwhile, the air’s magnitude depends on its viscosity and the relative magnitude of the viscous forces to the motion of the flow. This is expressed by a Reynolds number. Along the line’s surface boundary layer of low energy flow is generated so the magnitude of the skin friction depends on conditions in the boundary layer .

 

We can also think of drag as aerodynamic resistance to the motion of the fly line and leader through the air. This source of drag depends upon the shape of the Casting-Loop and the Line itself and the shape of the Leader and the shape of the Fly and is called “Form Drag.”  As air flows around the Line, Leader and Fly, the local velocity and pressure are changed. 

 

Since pressure is a measure of the momentum of the gas molecules and a change in momentum produces a force, varying pressure distribution will produce force on the line. The magnitude of this force depends on the combined effect of the local pressure times the surface area of the entire Fly-Line, Leader and Fly. 

 

Fly-Casting is based on the principles of basic flight. >> The component of the aerodynamic force that is opposed to the motion is the Drag; the component perpendicular to the motion is the Lift. Both the Lift and Drag force act through the center of pressure of the fly line. 

 

There is an additional drag component caused by the generation of lift, which is called “Induced Drag.” This is also known as “Drag Due to LIft.” Induced drag occurs because the distribution of lift is not uniform on a Fly-LIne, a Leader and a Fly.

The magnitude of induced drag depends on the amount of lift being generated by the line and leader and on the distribution of lift across the span. Properly formed loops have a minimum amount of induced drag.

Edited May 1 by CaryGreene

[Fishtale7]

Well done and extremely informative. Mods, make this a sticky for this forum! To the OP, I use Ande, for the butt, 60# (.031) for my 8wt & 80# (.035) for my 10wt. What's the consensus on stiffness between Ande and the SA for the butt section? My mid section is either Ande or Orvis, and the tippet is Orvis

[CaryGreene]

21 mins ago, Fishtale7 said:

Well done and extremely informative. Mods, make this a sticky for this forum! To the OP, I use Ande, for the butt, 60# (.031) for my 8wt & 80# (.035) for my 10wt. What's the consensus on stiffness between Ande and the SA for the butt section? My mid section is either Ande or Orvis, and the tippet is Orvis

Hi Fishtale, how 'ya been!? Thanks for the props. I've given Leader Design Seminars to fishing clubs that were WAYYY more detailed than what I posted above, but I wanted to keep it fairly simple here to get started. 

 

So you like trusty Ande Monofilament for your Butt Sections? Made in Germany - a trusted member of NATO! Ande makes a number of Monofilaments. Ande "Premium Leader" is a Medium-Soft material so it's more for bottom fishermen who want bait to behave naturally and move easily. It's not one I'd recommend for Fly-Fishing Leader making.

 

If constructing Freshwater Leaders, you're far better of with Maxima Chameleon (Brown)

for your Leader Butt Section, then if you like the Orvis Super-Strong, you could use that for the Tippet. I like the Frog-Hair Mono even better because again, it's very dull and non-reflective

but this is what I essentially do for Freshwater. 

 

I like Maxima even better than the SA material for Freshwater leaders - for the reason that it's a dull brown color and very non-reflective. It's also less stiff than the S-A material for sure, while still being stiff enough to do the trick. It has low memory too and you can straighten it multiple times with a Leader-Straighter (Leather or even Rubber) without damaging it.

 

For saltwater obviously, I'm going SA all the way. It's classified as a Medium-Hard, which is perfect for a Saltwater Leader. I might also use Fluorocarbon for a Saltwater leader and I'm sure we'll get into that topic soon. I started with basic Monofilament above though. 

Edited May 1 by CaryGreene

[Fishtale7]

Ande is readily available in my arsenal as I use it for leaders when plugging or soaking bait. I actually like the Orvis Super Strong Plus for the tippet, but am reluctant to use it for the butt as it tops out at .027.  I always wanted to try the Maxima Clear, but it maxes out at .024, I guess SA is in my future. As for NATO, pfft, toothless tiger. Well not so much toothless, just a deterrent I guess. 

Edited May 1 by Fishtale7

[CaryGreene]

1 min ago, Fishtale7 said:

Ande is readily available in my arsenal as I use it for leaders when plugging or soaking bait. I actually like the Orvis Super Strong Plus for the tippet, but am reluctant to use it for the butt as it tops out at .027.  I always wanted to try the Maxima Clear, but it maxes out at .024, I guess SA is in my future. As for NATO, pfft, toothless tiger.

I bet it's sloppy being gummed by a toothless tiger! LOL Yes Ande is solid for Spin/Conventional applications. I tend to use Berkely Trilene Big Game for Spin/Conventional Mono needs but Ande is excellent as well and they have a very loyal customer base. 

 

Sounds like you will very much enjoy the S-A for your Saltwater Fly-Fishing Leaders. Be sure to give your feedback here okay! Should be interesting!

[reel em in]

Great write up Cary. 
Quick question on the butt section of a leader. 
Berkeley Big Game  Trilene 100 lb has a diameter of .039. 

Accordingl to your chart that is not enough diameter  for a 10wt? You need .044 to .046 ?

Thanks in advance. 

[G8trwood]

Great post.

Taking a recent lesson to refresh my bad habits… The first thing my instructor said was your butt isn’t big enough. Switched out my 40 big game for 60 in my 8wt. Made a big difference. Now I have to go bigger, lol. He also said they same thing about half, don’t make it complicated, just half it. 6’ butt, 18” mid, 24” tippet.

 

 

 

[HL]

12 hours ago, CaryGreene said:

What is the optimal Saltwater Leader formula to achieve a desired Leader-length? >> For normal sized Flies, Begin with a Butt-Diameter approximately .010 Thinner than the Tip of your Fly-Line. 60% of your leader should be made of whatever diameter this material winds up being. 

Reelem...

Cary says 0.01 thinner on the butt than the fly line.

Herb

 

[reel em in]

28 mins ago, HL said:

Reelem...

Cary says 0.01 thinner on the butt than the fly line.

Herb

 

Yea I read that But I really don’t want to get into a micrometer. 
Herb 

please tell me if I am reading the chart right. 
Thanks 

 

[puppet]

Thank you so much for this Cary!!!

 

Can I ask what knots you use to assemble your leader?

[reel em in]

24 mins ago, puppet said:

Thank you so much for this Cary!!!

 

Can I ask what knots you use to assemble your leader?

Loop to loop now 

Now I’m thinking of adding a couple blood knots in there. 

[puppet]

2 hours ago, reel em in said:

Great write up Cary. 
Quick question on the butt section of a leader. 
Berkeley Big Game  Trilene 100 lb has a diameter of .039. 

Accordingl to your chart that is not enough diameter  for a 10wt? You need .044 to .046 ?

Thanks in advance.

I am not sure if it helps because as Cary notes lines vary.  I just measured a 10 wt SA floating line and a 9 wt OBS sink tip both measure .048"  .

In looking at different materials none are exactly  .038" , I suspect we get as close as we can.

 

 

[CaryGreene]

3 hours ago, reel em in said:

Great write up Cary. 
Quick question on the butt section of a leader. 
Berkeley Big Game  Trilene 100 lb has a diameter of .039. 

Accordingl to your chart that is not enough diameter  for a 10wt? You need .044 to .046 ?

Thanks in advance. 

Hi reel 'em, the rule of thumb is that your Leader Butt is .010 THINNER than the Tip of your Fly-Line. With a common 10wt Line, you should find that the Tip-Diameter of the line is between .044" and .046" - so you would SUBTRACT .010" and select an appropriate material with which to make your Leader Butt. The Leader Butt will likely be in the .034" to .036" range for most 10wt lines. 

[CaryGreene]

2 hours ago, G8trwood said:

Great post.

Taking a recent lesson to refresh my bad habits… The first thing my instructor said was your butt isn’t big enough. Switched out my 40 big game for 60 in my 8wt. Made a big difference. Now I have to go bigger, lol. He also said they same thing about half, don’t make it complicated, just half it. 6’ butt, 18” mid, 24” tippet.

 

 

 

Thanks G8trwood, your lesson story is similar to what happens at the beginning of many Guided Saltwater-Trips. The Captain/Guide knows the flies that the client will be using, they know the conditions & wind situation as well. The Leader Butt plays a huge part in all of this. They also know the species of fish being targeted, the water depth and Tippet that will be required. Often, the first thing they look at is Line Size, then they go right to the Leader to make sure everythings working together. 

 

When guides take a moment to pay attention to this, things run very smoothly and the client gets far better resutls - so it really benefits the Guide because ultimately, the right Leader helps the client and postively influences the Guide's Tip. Its a win-win. 

[reel em in]

6 mins ago, CaryGreene said:

Hi reel 'em, the rule of thumb is that your Leader Butt is .010 THINNER than the Tip of your Fly-Line. With a common 10wt Line, you should find that the Tip-Diameter of the line is between .044" and .046" - so you would SUBTRACT .010" and select an appropriate material with which to make your Leader Butt. The Leader Butt will likely be in the .034" to .036" range for most 10wt lines. 

Will go up to 60 lb or 80 lb Big Game

I have been using 40 lb. 

Thanks for a reply. 
You must be an awful busy guy with all this posting. 
I don’t know how you do it. Lol