The fly line is a very important component in the sport of fly fishing. Arguably the use of a fly line determines whether an angler is really fly fishing or not.
An artificial fly has next to no weight, certainly not enough to enable it to be cast without some kind of additional weight; the fly line is this additional weight. If you are not using a fly line you are not fly fishing.
Simply put, in fly fishing, the fly line line provides the weight that enables the angler to store energy in a fly rod by bending it. That stored energy is then released to propel the line towards the target, the fly really just goes along for the ride.
OK, that’s all basic stuff and probably old hat to most who are reading this, but not to all, so here are some more basics:
What Makes A Fly Line?
A modern fly line is a length of string (the core) with a plastic covering (the coating) applied! That also describes a clothes line, so what makes a fly line different?
The core can be monofilament or braided. Braided cores are generally better as they are less likely to hold a “memory” of the reel they were just pulled from. Memory is that very annoying tendency for a line to remain in coils no matter what you do. The core of the fly line also determines its tensile strength and how much it stretches. It can also help determine how stiff the line will be. For example, lines intended for fishing in warm tropical waters use materials designed to withstand higher temperatures than you might find in, say, Scotland, and to maintain their inherent stiffness.
The coating formulation and how it is applied to the core determines the rest of a fly line’s characteristics.
An important function of the line coating is to provide the casting weight needed to load (bend) the fly rod as mentioned above. Weight standards (for fly lines and fly rods) are set by the fishing tackle industry and the correct amount of coating must be applied to each line in order to meet these standards.
The density of the line’s coating determines whether it will float or sink. Floating lines have special micro spheres mixed into their coatings that enable accurate control of line density. Lines that are less dense than water will float. There is a trade off between float-ability and usability. Too many spheres will make the line thicker, more wind resistant and have higher friction through the rod rings (more difficult to cast), too few it will sink.
Floating line coatings also include hydrophobic agents to make their coating water-resistant and actually repel water making them float yet higher.
Sinking lines incorporate high-density materials into their coatings to make them heavier than water. By controlling how much high-density material is added to the coating, sink rates from as little as 1.00 inch per second or less to as much as 10 inches per second or more can be achieved.
Pigments, which determine the colour and visibility of the fly line are added to the coating.
Tapers and profiles. The line shape.
A fly line’s shape determines how energy is transmitted and / or dissipated when casting.
By varying the lengths, diameters and tapers of different parts of the line, various shapes or profiles are created and different casting performance characteristics can be achieved. It’s fair to say that this is probably the most over-hyped subject on planet fly line; everyone has an opinion of what’s best and most effective and no one can prove it right or wrong! Don’t worry about it; for ordinary fishing purposes the minutiae can be pretty much ignored.
The parts of the line shape are (please also see the above diagram):
Tip: a short level (parallel) section of a foot or so, where you attach your leader. This protects the line’s front taper. Anglers sometimes cut off a small part of the fly line when they change the leader, the level tip allows this without shortening the front taper.
Front Taper: this is the section of the line that determines how delicately or otherwise a fly hits the water. It is typically, 4-10 feet long and gradually decreases in diameter from the belly section to the tip. This gradual change (decrease) of the line’s mass (weight) determines how it transfers the casting energy to the leader and to the fly.
Belly: this is the widest diameter and thus the heaviest section of the line and consequently it is where most of the casting energy is carried. The length of the belly varies with the style or type of line.
Rear Taper: decreases in diameter from the belly to the running line. In weight forward (WF) lines, the rear taper creates a transition that is important to smooth casting. The length of the rear taper varies with the style of line.
Head: the head is the combination of front taper, belly and rear taper
Running Line: this thin section exists mainly to make casting more efficient by offering lower friction as a result of its smaller diameter. Since double taper (DT) lines are really just long belly lines with tapers and tips at both ends, there is no running line by definition.
Line Taper Types
There are several taper options: Level (L), Weight Forward (WF), Double Taper (DT), Shooting Taper (ST) – sometimes called shooting head. There are also ever increasing numbers of “speciality tapers” that are just variations of WF and DT and are of little or no benefit in most ordinary fishing situations, in fact they can, in some situations, be disadvantageous.
Level (L) With no taper at all, this type of line, in most situations, offers very low casting performance and is seldom used these days. They can be useful for very short range work, but then so can DT. These days level lines can be hard to find.
Weight Forward (WF) The WF profile allows you to make short or long casts to 80 feet or more. Most anglers find WF lines the most versatile and suited to a wide range of conditions. These lines come in many variations to meet specialized situations or to offer improvements, real or imaginary. All lines that have a head and integral running line can be considered WF. Rocket Tapers, Triangle Tapers, Extreme Distance etc are all WF fly lines.
Double Taper (DT) As they have an identical taper at each end, when the business end wears out or is damaged a DT line can be reversed. Two lines for the price of one? These lines are easy to mend and roll cast and are very good for short range work on moving water. DT floating lines are popular with small stream fly fishers. They are not so good for long casts. The long thick belly causes high friction through the rod rings and they do not shoot as readily as WF
Shooting Taper Also called “shooting head” these lines consist of two separate lines joined with a loop to loop connector. The front section (head) is similar to the head of a WF line. The rear section consists of a very fine diameter running line. Its purpose is to cut friction and gain distance. They are really extreme WF lines.
Standard Line Weights
It is important that your fly line matches the fly rod you are using and what you want to do with it. The AFTMA Fly Line Standard was developed to help fly fishing tackle manufacturers create a system that would match fly line weight to fly rod performance.
The system is American and therefore uses the weight (in grains) of the first 30 feet of fly line as a standard. But the units don’t matter. What is important is matching the line number to that recommended for the rod. The table below shows fly line number designations and their grain weight along with a tolerance that is considered acceptable.
Grain weights for the first 30 feet of the line.
| Line Number | Standard Weight (grains) | Acceptable Tolerance (grains) |
| 1 | 60 | 54-66 |
| 2 | 80 | 74-86 |
| 3 | 100 | 94-106 |
| 4 | 120 | 114-126 |
| 5 | 140 | 134-146 |
| 6 | 160 | 152-168 |
| 7 | 185 | 177-193 |
| 8 | 210 | 202-218 |
| 9 | 240 | 230-250 |
| 10 | 280 | 270-290 |
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