The graceful casts of fly fishing about which books have been written and movies made would not be possible without specialized fly lines. Conventional fishing lines are unable to cast flies, so we must use a specific type of line that allows us to cast nearly weightless lures.

When starting out, it’s easy to overlook the importance of the right fly line. A lot of the attention goes to rods and reels (which it should, fly rods and reels are awesome), though the reality is that a quality fly line is more important than the rod casting it and the reel holding it.

But what are fly fishing lines? What are the differences? Which one should you use? In this guide, we’ll answer those questions and more to equip you with the understanding of how fly lines work, why there are a variety of lines, and putting it all together to choose the best one to suit your needs.

What are Fly Fishing Lines?

Fly fishing lines are specialized fishing lines designed to throw (nearly) weightless flies. If you’ve ever tried to throw a fly on traditional fishing line, you’ll quickly realize that it won’t work. Yes, I’ve seen this happen and it ain’t pretty!

In conventional fishing, there’s enough mass in the lure that no special lines are necessary. Since this is not the case in fly fishing, we need mass distributed throughout the fly line itself in order to cast the weightless fly. When casted, the mass distributed throughout the fly fishing line creates enough energy from the rod into the fly in order to cast effectively.

So in fly fishing, we’re actually casting the line and not the fly. To do this effectively, mass needs to be distributed in the line in a specialized method.

There’s a variety of ways to do this, let’s take a look at how it’s done!

What are the Differences in Fly Lines?

There are differences in fly lines, such as weight, density, and tapers. There are similarities, especially in how we describe the anatomy of a fly line.

Dissecting the anatomy of fly lines, every fly line has a portion of “running” (or “shooting”) line and a section of line known as “the head,” all totaling around 90 or 100 feet for most typical fly lines.

The running line is the first 40-50 feet of the line that is easily controlled by the angler once casted and allows for smooth distance when flying through the air. This portion of the line is usually a level thickness throughout- if you’ve ever looked at and touched a fly line, you’ll be able to see and feel the difference.

The head of the fly line is the last 40-50 feet closest to your leader (check out more on leaders in The Beginner’s Guide to Fly Fishing Leaders) and controls how the line is casted. It is made up of 4 different parts:

• Back Taper
• Body
• Front Taper
• Tip

The length, density, and weight of these different sections differs from line to line, each designed for certain fishing situations. Understanding these different tapers and their purposes will help you pick out which fly line is best suited for your needs.

Fly Fishing Line Tapers

There are several tapers in fly lines, though two are by far the most common: the weight forward and the double taper.

Weight Forward Taper

Weight forward fly lines are the most common taper in modern fly lines. These fly lines, as the name suggests, carry additional weight and thickness in the front of the head to allow for better casting in windy conditions and larger fly patterns. The heads of these fly lines are typically shorter, which loads the rods faster and shoots the line further. The mass of the head shoots the line forward efficiently and brings the rest of the line along for the ride.

As we can see, much of the mass in the weight forward design is toward the head, allowing for more powerful casts when necessary. You can still make softer casts when using a weight forward fly line, though the extra mass in the front makes powerful casts easier when it’s necessary.

Double Taper

The double taper fly line is common when delicate presentation is a must. The longer body and gradual taper on each end sacrifices distance to the cast but gains a lot more “softness” to the presentation. These fly lines are still common, though losing popularity because of the versatility of weight-forward fly lines. Weight-forward fly lines can still present flies delicately (depending on the weight) while still able to cut through wind and cast larger fly patterns.

In the double taper design, the mass of the fly line is more evenly distributed through the head, allowing for delicate casts. This taper is perfect for dry fly fishing, or when stealth is paramount. The lighter, longer tip creates softer presentations, but struggles to turn over bigger flies.

If you’re just starting out, keep it very simple and pick up an all-around weight forward fly line and you’ll be set!

Fly Fishing Line Weights

Another critical element of fly fishing lines is the fly line weight.

Technically speaking, the weight of the fly line is measured by the weight of the last 30 feet of the line and is measured in grains. What is a grain you may ask? There are about 15 grains in a gram and since were beginning to use math and units of measurement no one has ever heard of, manufacturers have simplified the process and have created a scale instead.

For beginners, keep it simple and stick with the fly line weight that matches your rod. If you have a 5 weight rod, that means it was made to cast a 5 weight line, so go with that!

Fly Fishing Line Types

There are several different types of fly lines, all with specific uses depending on your situation. When people talk about the density of the fly line, they’re referring to whether or not the line is designed to float or sink.

Floating Fly Lines

Floating fly lines do what they say- float on top of the surface. While they’re used for fishing top water flies like dry flies and poppers, they are also used in nymphing techniques. You can also use floating lines for subsurface streamer patterns. As long as you’re not fishing 10+ feet water or need to get very deep in the water column, floating lines are the way to go.

Floating lines are very versatile and can be used in the majority of fishing scenarios. While there are times where floating lines are not the appropriate line to be using, they are fully capable of getting your fly where it needs to be in most fishing scenarios.

If you’re just starting out, pick up a floating line and you’ll be good to go!

Intermediate

Intermediate fly lines allow you to fish just under the surface of the water. These lines sink very slowly (about 1 to 1.5 inches per second) and can allow subsurface streamers to be fished under the water, but not too deep. These lines can be very helpful if you need to get your fly under the water quickly (but not too quickly), especially if you need to avoid snagging in weed beds or any other underwater structure.

There are certain times and places for intermediate fly lines, though a floating line can get reach the same effect in most ways. If you are honed in and wanting to maximize the effectiveness of your pattern, an intermediate line is the way to go.

Sink Tip

Sink tips are also conveniently named. These lines have the tip portion (the last 10-15 feet) made of a sinking material while the remaining portion of the line is floating. This allows your fly and first part of your fly line to sink down into the water column quickly without the entire fly line sinking to the bottom.

These fly lines are great for shallow water streamer fishing and similar to intermediate lines, they can get your fly under the water quickly and effectively, but not too deep. While some anglers say that the floating line portion causes the fly to swim unnaturally towards the surface, sink tip lines are used extensively in the streamer world. A lot of anglers also say that sink tip lines can also make casting more effective as the floating portion of the line allows for casting without needing to get your entire line out of the water.

Full Sinking

Knowing how the other types of fly lines function and how they’re named, it’s no surprise that full sinking lines do what they say: the entire fly line sinks down into the water. Instead of just a portion of the line sinking, the entire line sinks, allowing you to get very deep into the water column.

Full sinking lines are great when you need to get way down deep. You can even fish full sinking lines in shallow water with a fast retrieve, though most applications of these lines are used in deeper water situations.

Casting full sinking lines can be tough, especially when wading. Full sinking lines are used most often out of a boat, where the spare fly line isn’t swallowed by water on the deck of the boat.

You’ll see different types of sink rates, and even variable sink rates on sinking fly line boxes. This simply marks how fast the fly line sinks, anywhere from 2 inches per second up to 8 inches per second. The main takeaway is that the entire line of full sinking lines sink underwater, sometimes at varying speeds.

Saltwater vs Freshwater Fly Lines

When looking at fly fishing lines, you’ll also see a distinction between saltwater and freshwater lines.

Saltwater is more dense than freshwater, so saltwater lines can be made with smaller diameters while still floating. This helps casting in windy conditions. Freshwater lines need to be made with a slightly larger diameter to retain its floating ability.

Saltwater lines are also made with stiffer cores to be able to handle hot temperatures. Freshwater lines are made with more limp cores that perform well in colder waters, but still functional in warm waters as well.

Can you use a freshwater line in the salt? Unfortunately, no. Freshwater fly lines will go as limp as spaghetti noodles if used in hot, salty water. Plus, the coating of freshwater lines aren’t made to withstand salt and will rot very quickly. So if you’re fishing the salt, make sure you have a saltwater capable line spooled up!

Can you use saltwater lines in freshwater? Yep, you’ll be good to go. Saltwater lines perform well in warmer freshwater and some anglers even prefer these types of lines. You may notice that they get very rigid in cooler water, but unless you’re fishing very cold streams you’ll be fine!

Understanding Letters and Numbers on Fly Line Boxes

Manufacturers label fly line boxes in a specific way to refer to the taper, weight, and density of the fly line.

There may be slight variations to this method depending on the manufacturer but this is the general guideline.

Many fly line companies have begun to include diagrams of the tapers on the box as well. This helps visualize the running line and head portions of the fly line. The more you look at these, you’ll be able to tell if the fly line has an aggressive or gradual head, which will influence how it casts and performs.

In the example above, we have a fly line labeled “WF-8-F”. That means we have a weight forward, 8 weight, floating fly line. We notice in the taper diagram that much of the weight of the head is put towards the front, allowing this fly line to cast big, wind resistant bugs through the air. As the name suggests, this is a fly line designed for bass flies.

How Do I Know What Fly Line to Use?

With all these types of fly lines available, how do we know which one to choose?

First at foremost, match the fly line size to your rod. You can get away with going up or down one size, but in general, stick with the same weight as your rod.

From there, if you’re fishing in around 10 feet of water or less, stick with a floating line. This will give you the versatility of fishing every inch of the water column effectively without needing to change lines.

If you know you’ll be fishing exclusively subsurface, you have three choices: intermediate, sink tip, or sinking lines. As we’ve talked about, the advantages of each depend on how fast you want your flies to sink.

For beginner fly anglers, stick with a floating line that matches the weight of your rod and you’ll be set!

Conclusion

Fly lines are a crucial aspect of your fly fishing setup. A quality line goes a long way, many would argue that the right fly line is more important than your rod and reel. The wrong line will simply not let you fish correctly.

Fly lines come in many different sizes, tapers, and densities. For the beginner angler, keep it simple and match the weight of your fly line to the weight of your rod and use a floating line. That’ll cover the vast majority of your fishing situations. Save the specialty lines for when you get addicted!