Understanding Fly Lines
Taper Design
There are 2 types of tapers: Straight and Compound. There are 2 basic forms of the compound taper: Concave and Convex. These can be mixed and matched to accommodate the desired characteristics of the line.
Please note that none of the illustrations below are not to scale. They are all exaggerated to easier illustrate the concepts and characteristics being discussed. The red area is the taper, the blue areas are the belly and the tip.
Straight tapers are those that taper at an even rate along their length. Energy is dissipated smoothly through the entire length of the taper. To understand how a taper affects line turn over, visualize the taper as a road you are travelling on. A straight taper would be like an evenly gradual downhill slope on a road. Your car would begin to pick up speed as it moved along the slope and would accelerate at a fairly constant rate along the slope. So does the straight tapered line.
A good example of a gradual straight taper would be a Scientific Anglers Mastery Series™ GPX taper (below). It should be noted that the GPX line is 1/2 line weight heavy in each line weight class.
If the slope was steeper the car would accelerate faster than when on a gradual slope. Of course, once the slope leveled off the car would begin to decelerate. A shorter straight taper will also dissipate energy smoothly; it will just be more abrupt and may not feel smooth if the leader and fly are not matched to the line. A shorter straight taper would be used to turn over larger flys or to increase the amount of belly length in the line.
The Scientific Anglers Air Cell™ Bass Bug taper (below) fits the description here. You might think that the taper length difference between the Bass Bug and the GPX lines is negligible. But you need to also note that the diameter of the Bass Bug belly, foar a givewn line weight, is greater than the GPX due to the short head length. This increases the slope of the taper. When you combine this with the shorter taper then the effect is considerably more pronounced and creates a forceful turnover.
Concave Compound
A concave taper starts by dissipating energy quickly then drops off to gradual dissipation allowing for a light turnover of the fly. Consider a car initially starting down a fairly steep slope, then part of the way down coming to a more gradually sloped section. The car will accelerate at a fast pace to begin with then at the slope change the rate of acceleration will slack off. This type of taper is often used in situatons where a line with delicate turnover is required.
An example being the Scientific Anglers Air Cell™ Trout Taperwhich has a "Concave compound front taper for positive turnover and delicate delivery with typical trout flies."
Compound Convex
A convex taper dissipates energy less in the rear most portions of the taper, then it increases dissipation rapidly as it nears the tip. This is valuable for turning over large flys. In this case the car would first encounter a very slight downhill slope then a considerable steeper slope increasing the acceleration rate considerably.
Belly Length
In general, shorter bellies will load the rod more fully and quicker than a longer bellied line. These lines are made to cast heavier or air resistant flys a short distance. A good example of this kind of line is a Bass taper and some saltwater tapers. Though some of these lines may have heads shorter than 30 feet in length they will still comply with the AFTMA line weight standards. For the most part shorter heads are less than 35 feet in length.
Long belly lines allow the caster to carry more line out of the tip of the rod. This will generally mean a longer cast. These lines will also allow more line to be mended once on the water. Many of the line manufacturers make long belly lines. These lines are a favorite of Steelheaders and distance casters and are often marketed as such.
Note:
The large number of lines on the market reflect the needs of the average or below average caster to solve different fishing conditions. In most instances an excellent caster will do well with weight forward lines regardless of the conditions. If you are going on a special trip and want to improve your success ratio, get the right lines for the conditions. Market driven development will constantly bring more innovations as new tecniques and specialized equipment are brought forward.
Illustrations of tapers and line specs used used on this page are with permission from: 3M Scientific Anglers™
