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Choosing the Right Fly Line
written by Wayne E. Snyder

Fly-line design and coating technology has come a long way in recent years. This article will provide you with the basics for purchasing the right fly line for the kind of fish you want to pursue.
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Fly Line Guide
Since flies are nearly weightless, what you are actually casting when fly-fishing is the fly line.

Visit a well-stocked fly shop today and you may be overwhelmed with the different brands, line weights, line types and taper designs available, not to mention pricing. While this is a tribute to how fast fly-line design and coating technology has come in just the last few years, it can also be very confusing. This is where a trained and knowledgeable fly fishing professional can help you select the best line value for your needs.

By far, the most important two questions you'll need to be able to answer are "What is the designated line weight of the fly rod you'll be using?" and, "What kind of fish will you be targeting most often?" Your answer to these two questions will clue the fly shop professional in on the line weight you'll require, whether you need a freshwater or saltwater line, a floating or sinking line and the taper design best suited for your application.

But let's start with the basics.

What is a Fly Line and What Does it Do?

A fly line is a casting tool that consists of two parts -- the core and a coating. The core is generally a strong, braided nylon that is coated with a polymer such as flexible PVC to give the line "weight". There are other combinations of core and coating materials that give those fly lines unique handling characteristics. Most fly lines are about 90-feet long.

The primary function of a fly line is to deliver a fly to a fish. Since flies are nearly weightless what you are really casting when fly-fishing is the fly line. The fly line itself has all the "weight" needed to deliver the fly; the fly just kind of goes along for the ride.

Line Weight Explained

When we talk about line weight we're talking about the physical weight of the fly line itself. More specifically, were talking about the weight of the first thirty feet of fly line; that part of the line you will be casting the most. That first thirty feet of the fly line is weighed and measured in grains. Just for reference a "grain" weighs 1/7,000th of a pound. Generally, heavier lines can cast longer distances and bigger flies.

Many years ago the American Fishing Tackle Manufacturers Association (AFTMA) devised an improved way to differentiate fly lines. They took the entire line grain weight range and divided it into fifteen standard weights. All fly line manufacturers today use the AFTMA standard as part of their 3-part packaging code. Using the chart below you can determine that a 5 weight fly line can have a grain weight anywhere from 134 to 146 grains; however the standard weight is 140 grains.

AFTMA Standards for Fly Line Weights*

 Line Rating  Standard Weight (in grains)*  Grain Window
 1 Weight  60  54-66
 2 Weight  80  74-86
 3 Weight  100  94- 106
 4 Weight  120  114-126
 5 Weight  140  134-146
 6 Weight  160  152-168
 7 Weight  185  177-193
 8 Weight  210  202-218
 9 Weight  240  230-250
 10 Weight  280  270-290
 11 Weight  330  318-342
 12 Weight  380  368-392
 13 Weight  450  435-465
 14 Weight  500  485-515
 15 Weight  550  535-565
 15 Weight  550  535-565
* The Standard Weight indicates the weight, measured in grains, of the first 30 feet of line for each line rating.

Matching the Fly Rod to the Line Weight

Almost all fly rods manufactured today are matched to a specific line weight. The line
weight the rod is matched to is usually printed on the rod just above the grip. Simply stated, matching a rod to a line weight means that the rod will perform and cast best with the line weight specified. We call this a "balanced" outfit.

The 3 Basic Fly Line Taper Designs

The tapers designed into a fly line are the "thinning" and "thickening" of the line's coating material. Tapers determine the line's casting characteristics and how the line will "turn over" or unroll on the forward cast. By "turn-over" we mean that as the fly line rolls out on the forward cast, the loop straightens and with the last of the cast's energy transmits the final punch to the leader. There are three basic fly line taper designs: level, double-taper and weight-forward lines.

Level Lines - Level lines are the same diameter from end to end and really have no taper at all. These lines are the early predecessors to the double-taper and weight-forward lines we use today. They are the simplest of fly line types but very few are manufactured today and they are no longer the best choice for fly casting.

Fly-Line Three-Part Package Code
Fly-line packages are labeled using a standardized code that allows you to identify the line's weight, taper type and floating/sinking characteristics.

Double-taper Lines - Double-taper lines are level lines modified with a finer tapering point on both ends. Because these lines have a thicker and longer mid-section coating diameter they are superior to weight-forward lines for roll-casting, line mending and where casting beyond 30 feet isn't a factor. Many anglers who nymph a lot use double-tapers. Another advantage is that you can reverse a double-taper line on the reel and double the life of the fly line.

Weight-forward Lines - By far, weight-forward fly lines are the most popular and best choice for general purpose fly fishing. The whole point of weight-forward fly lines is to be able to "shoot" line, and thus the fly, longer distances. To accomplish this weight-forward line has its thickest coating portion in the first 1/3rd of the line. This thicker part is called the "belly" of the line. Weight-forward lines taper to a smaller coating diameter in the front to offer some delicacy in presentation and the last 2/3rd of the line is the thinner "running line" portion designed to minimize friction through the rod guides.

Sinking and Sinking Tip Fly Lines

Not everyone needs a floating fly line. Some fly-fishers will want to get a fly down in the water to fish at a desired depth. To do this, precise formulations of high-density substances such as powdered tungsten embedded in the line's coating produce specific sink characteristics and sink rates.

Sinking Tip Fly Lines - Sink-tip lines are floating fly lines that have up to 15 feet of the tip designed to sink. The normal depth range of these lines is from 1 to 4 feet but it is possible to get a fly down to 12 feet, depending on the sink rate you get.

Sinking Fly Lines - Full sinking fly lines are designed to get the fly down to deeper water depths than sink-tips, thus they have no floating portion. The normal depth range of these lines is from 4 to 12 feet but it is possible to get a fly down as deep as 20 feet, depending on the sink rate you get.

Manufacturers differ somewhat on how they code and label their packaging; however, the chart below will give you an idea of the sink rates available. The sink rate tells you how fast the line sinks stated in inches per second.

Sink Rates

 Sink Rate  Sink Rate Per Second  
 1  1/2 to 1-1/2 inches  Intermediate Sinking
 2  1-1/2 to 2-1/2 inches  Slow Sinking
 3  2-1/2 to 3-1/2 inches
 4  3-1/2 to 4-1/2 inches
 5  4-1/2 to 5-1/2 inches  Fast Sinking
 6  5-1/2 to 6-1/2 inches
 7  6-1/2 to 7-1/2 inches
 8  7-1/2 to 8-1/2 inches  Very Fast Sinking
 9  8-1/2 to 9-1/2 inches
 10  9-1/2 to 10-1/2 inches

Intermediate Sinking Fly Lines - Intermediate sinking fly lines are designed to get the line and fly just below the surface of the water and are mostly used for fishing shallow shore lines where a floating line will spook fish. Like full sinking lines they have no floating portion. The normal depth range of these lines is from just under the surface to about 1 foot.

Three-Part Packaging Code

Now that you understand line weights, taper types, and the floating/sinking characteristics of fly lines, you will understand how fly line packages are coded and labeled. This standard code helps you identify the line's shape, its weight and whether it floats or sinks.

Examples of the Three-Part Packaging Code

 DT-4-F  Double-Taper, 4 weight, Floating line
 WF-5-F  Weight-Forward, 5 weight, Floating line
 WF-6-F/S  Weight-Forward, 5 weight, Floating line with Sink tip
 WF-7-S  Weight-Forward, 7 weight, Sinking line
 WF-8-I  Weight-Forward, 8 weight, Intermediate line

"Species Specific" Fly Lines

To make fly line selection easier a few manufacturers have now developed "Species Specific" fly lines. In other words if you want to go bass fishing you buy a "Bass Taper" fly line; trout fishing a "Trout Taper" fly line; bonefish fishing...you got it, a "Bonefish Taper" fly line. There is some wisdom to all this and these lines were designed by consulting fly-fishing experts of particular fish species to determine the best features of the line they use; those features being line weight, taper design, and the floating or sinking characteristics.

Although it may seem a bit expensive for a 90-foot coil of plastic-coated string, there is a lot of thought and design work put into a modern fly line. Choosing the right fly line will make your casting more successful, and hopefully, your fishing more enjoyable and productive!

Tips to Remember When Purchasing a Fly Line

  • The two most important questions you'll need to answer to choose a fly line are "What is the line weight of the fly rod you'll be using designated for?" and, "What kind of fish will you be fishing for the most?"
  • A floating weight-forward fly line is the best all-round line to start with. It is the best one to learn to fly cast with and the one you will be using the most.
  • If your rod is rated for two line sizes (example: 5/6), buy the heavier weight line.
  • Buy the best fly line you can afford. Better fly lines not only last longer, they float higher and cast farther than less expensive lines because of internal lubricants in the coating.

Shop all Fly Lines.

Wayne Snyder is a Fly Fishing Team Leader at Bass Pro Shops Outdoor World in Auburn Hills, Michigan. 

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