Fly Lines & Backing

Fly lines come in different lengths, weights, tapers, colors, and more! It can all seem daunting at first, but the mystery of fly lines can be unravelled somewhat by first learning their key aspects. Buying the wrong line can both hurt the performance of your rod and your overall success rate, so you must choose wisely. Let's end this intro and venture into the world of fly lines!

Fly Line Coating/Core

Fly lines are constructed with a core and an outer coating. Depending on the line's intended usage, the core will be comprised of a soft material like braided nylon or a stiffer one like monofilament. Around the core is the coating which is normally a type of plastic. While the special coating of a floating line may contain small air bubbles to help it float, a sinking line is both thinner and incorporates material like powdered tungsten in the coating to help increase density so it will go below the surface.

Temperature has a big impact on line selection. Hot weather can make some lines sticky/gummy, while cold weather can make others overly stiff and tough to manage. Fly line manufacturers make lines with stiffer cores and harder coatings specifically for hot temps (often referred to as "tropical" lines), while more supple lines work well for the average conditions many anglers face.

Line Weights

Unlike normal line used in conventional fishing, fly line is rated by physical weight rather than breaking strength. Lines have their first 30-feet weighed in grains (minus the short level tip section) then are assigned a numbered "weight" rating based on this measurement. This system was first implemented long ago and is maintained by the American Fly Fishing Trade Association (AFFTA) to provide a standard baseline of line weights. For example, a certain floating line weighing between 134-146 grains in its first 30-feet would be classified a 5-weight line using this system.

With all of this said, the aforementioned system is not always closely followed. Some fly lines actually weigh more than their corresponding weight range indicates. The first 30-feet of a certain 5-weight line may weigh 160-grains which would seemingly classify it as a 6-weight line! With many modern fly rods being faster in action, heavier lines can be good matches for these stiffer high-performance sticks.

Line Length/Taper

(These images courtesy of RIO Products)

Fly lines typically span 80–100 feet but also come at even greater lengths. Each line has a specific design that gives it the right properties for casting and performance. There's two main tapers to focus on:

The weight-forward (WF) taper is the most common. This taper puts the thick, heavy section in the forward portion of the fly line. WF lines are popular because they are great for so many fly fishing situations and conditions. There's also many specialized taper configurations available if you want to grab a line that's optimized for the exact type of fishing you do.

A double-tapered (DT) line has the taper extending from the center out to both sides. Since these lines are the same on each end they can be reversed if one end gets worn out. DT lines are good choices for shorter casts and delicate presentations.

Floating Lines

Floating fly lines are very prolific in the sport of fly fishing. They are generally easy to cast and allow for easy line management since the line doesn't sink. Just because these lines float doesn't mean they are only good with flies that float. If the fish aren't too deep, a floating line along with a wet fly may be all you need. Like all lines the prices vary, but the better offerings out there are often touted as being higher floating than others. An example of line labeling for a 5-weight floating line would appear as "WF5F" which stands for "Weight Forward 5-weight Floating."

Sinking Lines

The two types of lines in this category are full sinking lines where the whole line sinks (great for keeping flies deep) and sink-tip lines where only a short portion of the line sinks while the rest floats (perfect for getting flies down while still being able to easily control/mend the floating portion). Every sinking line is made to descend at a certain speed and carries a certain sink rating. 


Just like floating lines, the advertised grain and line weight of a sinking line helps match it to a particular rod. However, it is the density of a sinking line that determines how fast it sinks. There can be a 200-grain sinking line that sinks slow, yet another 200-grain sinking line that's made to sink fast. Manufacturers design lines like this so you can own multiple lines with varying sink rates for just one rod size. 


Sinking lines are usually given a name/number rating to show their sink rates. The inches-per-second (ips) at which it sinks is often shown as well. Starting out, a line labeled "intermediate" sinks very slowly at maybe 1–2 ips. Beyond intermediate, lines sink faster and will often be classified by a name like "type" along with a number. For example, a Type 3 line may sink at around 3 ips, a Type 5 around 5 ips, and so on. The exact sink rate can vary, however, so it's best to look at the ips range listed by the manufacturer just to be safe! 


Backing is normally a thin, low-stretch braided line that goes onto the reel first and the fly line is tied to it. Backing serves two purposes. First, it bulks up the spool diameter allowing for a faster retrieve ratio. Second, since fly lines are so short, backing gives you many yards of extra line capacity to work with should a strong fish make a long run that exceeds the length of the actual fly line. Two main varieties are available and are both simply rated by the breaking strength:

Dacron: Easy to find, easy to handle, and relatively affordable, Dacron is a popular choice for many situations. You'll find this backing widely available in 20 and 30-pound tests.

Gelspun/Spectra: This type of backing is usually pricier but has a very thin diameter compared to the rated poundage. The thin diameter of gelspun/spectra gives you the option to fit more and stronger backing onto your reel. This makes it popular with anglers who target big, long-running fish and need that advantage.