Choosing the Right Fly Line: A Complete Guide

What is a Fly Line

A fly line is a specialised fishing line used in fly fishing. This method of angling relies on the weight of the line itself to cast a lightweight artificial fly. Unlike traditional fishing methods, where the weight of a lure or bait propels the cast, fly lines are designed to provide the necessary weight and control for accurate casting.

Key Components of a Fly Line

A fly line is constructed of 3 main key componenents:

The Core: The inner material that provides the fly lines strength and flexibility ie: How stiff the line is and how much stretch there is in the line. The core is often made from braid or monofilament. More expensive lines are usually made from braid and have less stretch which allows for increased sensitivity and better line control and management.

The Coating: The outer layer, typically made of PVC or polyurethane, adds weight and buoyancy to create the lines density (which we touch on later in this article) while providing the line a smooth coating to help reduce resistance through the rod guides while casting.

The Taper: The taper provides the the shape and the distribution of weight along the line, which affects and determines casting distance, accuracy, and fly presentation. We breakdown line tapers later on.

Types Of Fly Lines Explained

FLOATING LINES – If you only purchase one fly line, make it a floating line. These lines are the most all round and easy to use, additional sink tips can be added or weighted flies if you need to fish a little deeper.

INTERMEDIATE LINES – Moving on from floating lines are intermediates which normally sink at a rate of 0.5 to 1.75 inches per second. These lines are great for fishing flies in the top layer of water but have the added bonus of not disturbing the water surface.

SINK-TIP LINES – these lines are a blend of floating/intermediate lines in that they are a floating line with a sinking part towards the end. The sinking part can vary anywhere between 1ft to 15ft. Sink tip’s are very popular now and come in a variety of sink lengths and sink rates to cover all preferences.

SINKING LINES – complete sinking lines are useful in deeper waters but also essential when fishing from a drifting boat. Faster sinking lines will to point out the obvious sink quicker but this becomes more pertinent when you require the line to sink to the desired depth before drifting over the line while fishing from a boat.

SWEEP LINES – Sweep fly lines are a specific type of sinking fly line designed with varying sink rates/density along their length Different sections of the line sink at different rates (e.g., the tip might sink faster than the belly or rear sections). This unique design allows the line to sweep through the water column during retrieval, covering multiple depths effectively.

BOOBY BASHER LINES – An ultra fast sinking line with a short aggresive head. These lines are designed for targeting fish that are tight to the lake/loch bottom with bouyant flies such as its namesake, the booby.

Fly Line Density Explained

As we touched upon earlier in the post, how the coating of a fly line dictates its density. Below, we have put together a table that explains the different line densities that are available and what scenarios you would use them.

What Does The 'DI' Stand For?

In fly lines, DI stands for Density Index, which indicates the sink rate of the fly line. The rating helps fly anglers choose the correct fly line for the conditions.

Understanding Fly Line Tapers

What is a fly line taper?

A fly line taper refers to the overall profile of a fly line design. Line profiles can be manufactured to vary in line thickness at various points in the fly lines length through a tapered design. Thicker denser parts of the fly line are used to add weight and mass. Thin areas of the fly line are used to reduce friction and offer better presentation. The transition from thick to thin can be gradual or steep tapers offering vastly different performance outcomes, depending on your fishing objectives.

Basic fly line profile:

1. Thicker heavier parts of the line are used to add weight and mass. Weight forward lines have weight towards the front of the line to load the rod quickly.

2. Thin parts of the line, like the shooting line, offer less resistance on your rod eyes. A fine taper on the front of the line will allow for delicate presentation.

3. The taper from thick to thin or vice versa allows for a smooth transfer of energy. A line with a long gradual front taper that tapers fine at the front will offer a smooth delicate turnover for presenting smaller flies.

4. A steep/aggressive short taper can be used to turn over heavier weighted tips or flies.

There are a multitude of unique line tapers, but there are 4 or 5 that are most commonly used, these slightly differ between various line manufacturers.

Line tapers are created to provide individual characteristics to a fly line; these enhance features such as casting distance and overall fly presentation.

The Mechanics of a Fly Line

A fly line is made up of 2 major components. The running line, which is the rear end of the fly line, this connects to your backing line. The running line is then connected to the head of the fly line, this made up of the rear taper which is then connected to the belly of the fly line and then the belly is connected to the front taper. Below, we look through these 4 components and how they work.

Running Line

The running line of a fly line often referred to as a shooting line is thinner and lighter than the head and normally has a level taper. Distance can be achieved easier as the narrow diameter of the running line creates less friction through the fly rod guides.

Head

The head of the fly line is made up of 3 sections, below we highlight these sections and explain how the mechanics of these sections work.

Rear Taper

The length of the rear taper determines how smoothly the energy is transferred to the belly of the fly line. A longer rear taper can hold the fly line head steady in flight offering more accurate casting. Lines with a longer back taper can be cast at various distances along the back taper. Lines with a longer back taper can be useful if you want to aerialise a long line and achieve good accuracy at distance.

Compare this to a short back taper where the line can only be false cast only with the rod top near to the back taper. An advantage of a heavy head and short back taper is that you can load the rod quickly and cast distance with fewer false casts. Beware if you have too much-running line out the rod tip while casting, the line will collapse as the thin running line cannot transfer the energy of the cast to the head.

Belly

This section of the fly line carries the thickest diameter and also carries the majority of the weight and, therefore, helps load the rod shoot the fly line. Longer bellied fly lines help increase casting distance and accuracy as they allow the angler to carry out several false casts at various distances without the chance of casting into the running line.

Shorter bellies load the rod quicker and cast easily as the mass or weight of the fly line is concentrated into a smaller length.

Accuracy and presentation can be sacrificed though, as the shorter the belly and front taper are the more aggressive the line can wander during flight.

Front Taper

The length of the front taper of a fly line will determine how a fly is delivered (or how it will turnover). The longer the front taper is the more delicate the presentation will be, as the energy is distributed evenly over the length of the front taper. Shorter front tapers mean more powerful turnovers because the energy is transferred from the belly to the tip much quicker. This provides a far more aggressive turnover and can impede fly presentation if not used in conjunction with the appropriate setup.

Fly Line Tapers and When To Use Them

Fly line tapers can become quite confusing, so below we have highlighted the most commonly used fly line tapers and broken them down into specific fishing scenarios to provide you with a better understanding how each individual fly line taper works.

1. General All Rounder

For general use, we would recommend something with a fairly standard head length, around about 35-40 foot with a 5 to 7-foot front taper.

This style of line taper is classed as a great all-rounder and is generally favoured by general Stillwater anglers. These fly lines are easy to cast and provide good fly presentation which is ideal for a beginner who is trying to hone their casting skills.

This style of fly line tapers is ideal for casting teams of flies. They do have limitations though, so if you’re fishing a specific method, we do recommend looking at some of the specialist fly line tapers that we cover below.

2. Dry Fly

When dry fly fishing with a tapered leader and a single dry fly, you will want to use a very fine and long front taper.

You want to look at a 45-foot head length on your fly line. This will provide an elegant turnover while the belly of the line will transmit enough energy to turn the fly over. Having the weight towards the rear of the head also allows the line to be controlled and mended. (see diagram below)

If you try and turn over something like a big heavy indicator on this style of taper, it’s not going to have the mass required at the end of the line in order to turn it over efficiently due to the long front taper. You are going to really struggle as the transmitted energy will dissipate due to the mass being spread over a long belly length and a long front taper. Think of it like creating a rope wave using your arm, the wave created initially is strong and high but the further down the rope the energy is transferred the smaller the waves become.

If you’re looking to fish a team of dry flies on a tapered leader then we recommend using a fly line with a slightly longer rear taper and shorter belly to allow you to keep your flies in flight longer. The shorter concentrated mass helps shoot the line easier, while the elongated front taper will still turn over the flies more elegantly.

The shorter belly length is a popular choice with reservoir anglers that cast teams of flies and also provides a good all-round dry fly line. The shorter belly provides the required concentrated mass for shooting these lines at distance easier, while the extended rear taper allows you to keep more line in flight for increased distance and accuracy.

3. Nymph Fishing

These lines have a very short and acute front taper. This style of taper is designed for casting a great big air-resistant indicator, primarily aimed at the sight indicator angler where casting big thingamabobbers or similar style indicators is common practice.

UK fly anglers take influence from the American market when it comes to fishing indicators where a longer back taper is required so they can mend the line easily when fishing rivers. This gives them more control of the line with that longer head but also gives them the ability to keep more line in flight for improved distance and accuracy.

UK Stillwater anglers find these tapered lines beneficial for fishing the bung. The bung is not the most aerodynamic indicator and requires a short front taper to provide that aggressive turnover needed for larger flies or indicators.

If we tried using a really short shooting head it would be near impossible to mend the line effectively because the thin running line would not be able to move and manipulate the short heavy shooting head.

Think of a matchstick trying to pick up an anvil, it’s not possible. We require mass to move mass, this is when the elongated rear taper comes into its own.

4. Casting Competition

The one thing that new anglers get confused with is the naming on packaging, for example, they see a fly line advertised as a distance line and think “I’ll buy that and I’ll be able to cast really easily because it’s a distance line” but in actual fact, they should be looking at the line taper to distinguish if the line is appropriate for them.

Most distance lines are going to be more suited to a more advanced fly caster because it’s got a really long, elongated tapered head on it. This means the whole fly line can support itself during flight when more line is paid out during the cast. The fly line’s mass is spread over a longer head length of the line, which means more line in flight will vastly improve accuracy and distance.

Distance lines or long belly lines are ideal for fishing teams of flies and are designed for the more experienced or competent caster to really get the best from these lines.

The downside to a really long belly and an elongated back taper is that you need a lot of line out to really have the weight of the line to load the rod.

As a result, an average caster or a beginner is not going to have the ability to handle a line that long. They will not be used to managing that much line out of the rod tip, particularly if they have been using a really short and heavy fly line taper, like a more standard head length.

5. Tight Casting

If you’re fishing with limited backcasting space due to tree-lined banks or steep banks, then you require a fly line with a shorter belly and shorter front and rear tapers.

This will allow you to shoot a lot of line with minimal false casts. The shorter head and shorter front and rear tapers will load faster due to the shorter concentration of mass. These fly lines are easy to cast and are ideal for casting larger flies or teams of flies, especially into a headwind.

These fly line tapers are also good for roll casting and Spey casting with a single-handed fly rod. They are good because there’s a shorter concentration of mass to load the rod quickly, however, they turn over aggressively so are not appropriate when a more finesse presentation is required.

How To Choose The Right Fly Line

Matching the weight of your fly line to the rod is important. Thankfully all lines and fly rods are weighted and rated with a number, so you can match this number to your fly rod weight and you’re good to go. The most common line ratings are #5 to #8 for trout rods and #8 to #11 for salmon lines. Although the fly line weighting system (AFTM – association of American fishing tackle manufacturers) is a good system to easily identify the correct weight we can go outwith the rating system for desired results.

Not confuse you but it is common to go a line size heavier, particularly with a floating and can also be advantageous when learning casting. This is because the line feels heavier on the rod which allows the users to better feel the rod loading and unloading. If you are in a situation where your rod is rated a straight #7 and the line you’re looking to purchase comes in dual sizing i.e. #6/7 or #7/8 – you should purchase the heavier option. It’s always advisable to err on the heavier side as the line will load the rod easier. Having an underrated fly line on your rod will feel like hard work as you can’t load the rod or may even be impossible to cast line out at all.

Fly Line Rating Guide