The fly line and leader are important parts of fly fishing physics. The line is what is cast since the fly is virtually weightless. Fly lines come in a variety of forms. They may be of varying diameters, contain tapered sections, or be of level (even) diameter. A fly line may float, sink, or have a floating main section with a sinking tip. A modern fly line consists of a tough braided or monofilament core, wrapped in a thick plastic sheath, often of polyvinyl chloride (PVC). In the case of floating fly lines, the PVC sheath is usually embedded with many 'microballoons' or air bubbles, and may also be impregnated with silicone or other lubricants to give buoyancy and reduce wear. Fly lines also come in a variety of models for use in specific environments: fresh water, salt water, cold or tropical temperatures, etc.
A fly line is matched to a rod according to weight. Fly lines come in a wide range of numbered sizes (from a thin #0 to a hefty #16) as well as profiles: double-tapered, weight-forward, shooting-head, etc. Most fly lines are 30 yards (27 m) in length, sufficient for sporting purposes, though specialized shooting-head lines with a short, heavy front section and small-diameter backing are sometimes employed for casting long distances or in competitive casting events.
The American Fly fishing Tackle Manufacturers Association (AFTMA) is a trade association responsible for the standardization of many of the lines and rods used today. Line weights are standardized on the weight, in grains, of the first 10 yards (9 m) of the line. Including a small allowance for production variations, the following are standard line weights:
The American Fly fishing Tackle Manufacturers Association (AFTMA) is a trade association responsible for the standardization of many of the lines and rods used today. Line weights are standardized on the weight, in grains, of the first 10 yards (9 m) of the line. Including a small allowance for production variations, the following are standard line weights:
Tapering of the tip section is a consideration in purchasing a line. A heavier taper near the tip of the line, usually designated as a weight forward line, loads the rod sooner and makes casting easier for beginners. A double tapered line can be used twice as long since the taper is the same at both ends of the line, thus one can wear out one half and turn it around and use the other half until it is worn out (this can not be done with any other fly line). The taper of a line is prefixed to the line weight such that a line labeled L7F is a 7wt, level (not tapered) floating line whereas a WF9S would be a 9wt, weight-forward, sinking line, etc.
In order to fill up the reel spool and ensure an adequate reserve in case of a run by a powerful fish, fly lines are usually attached to a secondary line at the butt section, called backing. Fly line backing is usually composed of braided dacron or gelspun monofilaments. Backing varies in length according to the type of gamefish sought, from as little as 75 yards for smaller freshwater species to as much as 300-400 yards for large saltwater gamefish. Another purpose of the backing is to "fill out" the spool. A full spool results in faster line pickup than does one only partially filled.
Between the line and the fly is attached a leader of monofilament or fluorocarbon fishing line, usually tapered in diameter, and referred to by the 'X-size' (0X, 2X, 4X, etc.) of its final tip section, or tippet. For example, a freshwater trout leader might have a butt section of 20-pound test monofilament, tapering through 15, 12, 10, and 8-pound test sections, terminating in a 5X (.006 inch diameter, usually around 4 pound test) tippet. A fly line is only as strong as its weakest link, which is the final tippet section. As defined, the diameter of a tippet is defined as the number, in thousandths of an inch, that the diameter is less than 0.011 inches. For example, a 5X tippet is (0.011-0.005)=0.006 inches in diameter. Similarly, a tippet that is three-thousandths of an inch (0.003 inches) in diameter would be 8X (i.e. (0.011-0.003)=0.008 inches).
When using nylon tippets, the approximate breaking strength, in pounds, can be estimated by subtracting from 9 the X-value of the tippet. For example, a 6X tippet will break at approximately (9-6)=3 pounds of pull.
The various portions of the leader are: 1) the butt section which is typically the thickest portion of the leader and is attached to the fly line; 2) the mid section; and 3) the tippet which is the thinnest segment of a tapered leader and is attached to the fly. Sometimes, the tippet is separated from the fly by a short heavy section known as a "bite" or "shock" leader the purpose of which is to resist the sharp teeth of certain fish species or the sudden, instantaneous strong impact when a large fish takes the fly. The shock or bite leader is a piece of large-diameter monofilament or a braided or single-strand wire such as stainless steel.
Given the extended UV stability and strength of the relatively new fluorocarbon lines and tippets, most anglers attempt to maximize the recovery and minimize the loss of fluorocarbons into the environment where they can entrap or sicken small mammals, birds and fish.
