A fisherman's guide to fly lines

By Mike DavisNZ Fishing World
A fisherman's guide to fly lines

The fly line is one of the most integral components to a high preforming fly set, yet one of the least understood by anglers, world over. You may have just spent thousands on the latest high-end rod and reel but if you put the wrong fly line on, it will still cast like a dog.

Choice, mate

Trouble is there are so many different types of line and different brands to choose from. It helps to be aware that the major players in the New Zealand market are Airflo, Rio, Scientific Anglers and Cortland. Most of the others are made under licence by one of those four companies. 

A while back it was the thing to buy a general purpose, weight forward line, but manufacturers have started to produce fly lines in a range of varying tapers for specific situations. Modern lines can be designed to cast big, heavy flies, but you can also get a line in the same weight that is supple enough to land lightly when casting short. 

A fisherman's guide to fly lines

Change has been driven by advancements in fly rod technology. As the rod has become faster and lighter the tapers of the line have had to change to balance the set correctly. People are also aerialising more line to help them feel the rod load and unload. This has basically seen the end of the level and double tapered fly lines, leaving just the weight forward line with specific tapers. These advancements ultimately make the cast easier and more enjoyable.

The core of the matter

A fly line consists of two major properties, the core and the coating. The core determines the lineís strength and stiffness. Most lines up to a six weight have a 20lb core, while the big seven weights and heavier usually have a 30lb core.

Braided cores are usually found in floating lines. A braided multifilament is very supple giving less memory in the line. This is particularly important when fishing the cold waters of New Zealand, especially on the lakes in winter. They trap air for better buoyancy and stretch more when under load, which helps when playing fish in close.

A fisherman's guide to fly lines

 Such gin clear and calm conditions casting the correct fly line is a surreal experience. Just add fish and it's a match made in heaven.

Monocore lines (coated monofilament core) have been used in floating lines and are good in warmer climates but in our colder waters they suffer from excessive memory. However, when it comes to sinking lines the monocore comes into its own. Monocore sinking lines allow all the air to be extruded from the line so more consistent sink rates can be achieve, even with different weights of line. 

The monocore fly line also allows the manufacture to vary core stretch for different sink rates. This means the fastest sinking fly lines use very low-stretch cores to give better bite detection, improving the angler's hook setting ability when fishing down deep. 

A fisherman's guide to fly lines

Subtly different conditions often require niche fly lines. In this case the angler on the left is working harder to present upstream where the angler on the right requires a more delicate presentation on
still water.

Colour me bad 

Fly line colour has always been a topic of hot debate in New Zealand. Whatever your view, you must be able to see the line on the water so mending can be done at the correct time to achieve drag-free drifts. 

It’s probably a good idea to keep a variety of colours on you, some bright, some dull. When fishing in smaller waters with a presentation line, the dull, natural coloured fly lines will reduce flash on bright sunny days. The last thing you need if fish numbers are low is to accidentally spook a fish with harsh light reflecting off a bright coloured line.

A fisherman's guide to fly lines

When targeting spawning fish I prefer to use a more visible line that I can follow at a long distance when casting big. A brighter line can be seen from far away so mending becomes easy giving better drag free drifts. Spawning fish sit on the bottom of the river meaning line colour is less important.

Most New Zealanders hate bright orange fly lines but they can be handy when drift fishing on smaller lakes with a team of flies. When nymphing lakes without an indicator something is needed to detect subtle takes and the bright fly line allows the angler to focus on the tip of the line so any movement can be struck at quickly. Because boats drifts down wind onto the fish as they are swimming upwind, the flies cover the fish first before the bright line moves over them.

Fly line anatomy 

A fisherman's guide to fly lines

TIP: Level section at the end of the fly line allowing the user to change leaders without cutting into the front taper. Helps improve the lines casting ability. Typically up to 30 cm long.

FRONT TAPER: The length and diameter of the front taper will dictate how the fly is presented on the water. A long front taper will land a fly gently by dissipating energy through its length. A shorter front taper will transfer energy faster making it more aggressive – great for heavy flies.

BELLY: The belly has the largest diameter through the fly line. This is where all the casting energy is held. Longer bellied fly lines cast further and are accurate over distance. Short-bellied fly lines can load the fly rod very quickly; so high line speed can be gained with minimal false casting. Great for tight casting situations.

REAR TAPER: The shape of the rear taper will dictate how smoothly a fly line can be delivered. This area of the fly line sits near the rod tip during the final false cast. The smoother the transition between the rear taper and the running line, the more control you’ll have. A long rear taper helps with distance and control.  Short rear tapers create lots of energy for a fast casting stroke. 

RUNNING LINE: The running line is the very thin level line behind the head.  This section varies in length depending on the length of the taper of the head being used. The running line is designed to be very light so it is pulled through the rod guides easily, helping gain maximum casting distance. 

Get your coat 

The coating of the fly line is the shell around the core that is made up from a series of polymers or plastics. There are two main coatings used. American companies like Rio, Cortland and Scientific Anglers use a PVC coated product and the European companies such as Airflo make their fly lines from a polyurethane based product.

The PVC coating feels lovely in the hand and performs extremely well to start with, but has a tendency to suffer from radial cracking after a few hard months of use in New Zealand. This is because of the chemical make up in our water, which damages the PVC bonding of the line ñ especially in the volcanic water of the Central Plateau.  

A fisherman's guide to fly lines

Polyurethane based lines have much higher chemical resistance, but also a slightly harder surface area. They are not quite as supple in the hand but can be used hard for a couple of seasons without a drop in performance.

The density of the coating determines whether the fly line will sink or float. Floating fly lines have tiny air bubbles trapped inside the coating to help with buoyancy. The density of these bubbles can be increased in certain parts of the fly line, (such as the tip/front taper section and the belly), to help with floatation. The outer surface of the line carries hydrophobic properties to help repel water and dirt. Keeping the surface of the fly line clean helps it float higher and cast more efficiently for longer periods. 

In sinking lines tungsten powder is impregnated into the line adding weight. By varying the amount of tungsten used in different areas of the line you can compensate for density allowing the line to sink straight and not suffer from sag; you donít want the belly sinking faster than the tip. Because tungsten is so heavy the diameter of the sinking fly line is greatly reduced making sinking fly lines much easier to cast than floating lines, this helps them to cut through the air much faster as they are dense and have less surface area. 

Advanced fishing

The advancements in fly line technology over the last ten years have been huge.

The first lines on the market 60-70 years ago were made of silk. They needed to be dried after every day fishing otherwise the line would rot.  Nowadays fly lines are made from some of the most expensive and durable plastics on the market, so they last longer and cast further than ever before.

Don’t taper out

A fisherman's guide to fly lines

When fishing in larger waterways like the Tongariro or some of the large South Island rivers, big casts are often needed to cover all of the water. Conditions are often windy in the large river valleys and this is where the long bellied fly lines work extremely well. Long belly lines usually have a short aggressive front taper and a long rear taper; turning over heavy flies at long distances. The long rear taper will help when it comes to mending line at long range and will help to aerialise more line in the air when false casting so all distances can be covered. Long belly lines are made from stiffer coatings so they can cast further and turn over energy positively by reducing friction through the rodís guides; ideal for loading the fast tip action rods that have become popular over the last few years. 

But an aggressive long belly fly line is not the answer when it comes to fishing smaller backcountry rivers or where delicacy and presentation is important. When shorter casting is needed the use of rods that are softer in the tip are necessary, a line with a short belly will load these fly rods quicker and the long front taper of the presentation line will turn the flies over with accuracy. 

Typically lines with long front tapering sections are very soft and supple so they become a joy to cast with at short to mid range distances. Long front tapering lines allow the angler to slow down their casting stroke for maximum control in tight bush-lined streams. These lines have less memory and the core allows some stretch ñ useful when playing large fish in close quarters.

Remember, fly lines are now designed to perform specific tasks for niche situations so donít baulk at the price of the modern day line. Itís the most important hundred dollars in your arsenal - after your flies. The fly line is crucial in determining how the flies are presented to the fish, and how the line and the flies will be controlled as they travel through the air. Skimping here will lead to a leaner catch.

Advanced fly lines

With advancements in technology come increased choice and complexity. We advise getting expert advice.

A one-minute stroll through specialist store Rod and Reel in Newmarket, Auckland, revealed the sheer scale of lines available to the modern angler. This is a just a taste of what to expect next time you upgrade.


A fisherman's guide to fly lines

Beautifully packaged the new Cortland Trout Boss weight forward floating line is designed to load fast action rods quickly for tighter loops and extra distance. It floats higher in the water than its predecessor as well.


A fisherman's guide to fly lines

Sink tip lines incorporate a heavy grain (in this case 400grain) front section with a floating line behind. As a rule sink tip lines allow anglers to reach deeper in the water column while maintain the control to throw a mend.


A fisherman's guide to fly lines

The Rio InTouch Deep 3 is a sinking line with a decent rate of three to four inches per second. This is a relatively fast sink rate and could be used for lake drop offs with a relatively strong rip. A good line for stripping booby flies.


A fisherman's guide to fly lines

The Rio InTouch Deep 5 is a sinking line with a decent rate of five to six inches per second. An even denser line than the Deep 3, the Deep 5 is good for deeper lake drop offs and to swing wet flies in heavy rivers.


A fisherman's guide to fly lines

A speciality spey line, the Technical Shooting Line offers virtually zero stretch allowing spey anglers to stay completely in touch while swinging flies in big rivers, with a highly visible front section to time recasts perfectly.


A fisherman's guide to fly lines

Specifically designed for the largest of tropical species, the Leviathan Saltwater features a powerful front taper to cast the biggest of flies, and a short, heavy head to load blue water rods super fast. 


A fisherman's guide to fly lines

With an aggressive front taper the Outbound Short casts weighted flies very long distances, while the powerful head loads rods for effortless casts. A range of densities make this a versatile line series.

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