Fly lines: an overview of all types and when to use them

17th of August 2022

Fish are found at all depths, so you’ll eventually need a range of fly lines that can go with them. Here’s a guide to what you’re looking for.

Floating lines 

These make the ideal first line if you’re new to fly fishing. They are relatively light to help them float and that same lightness means that you can keep them airborne easily when casting.

Once your leader is attached to it on the other end, you can fish depths equal to the length of the leader. Anything up to nine feet or more, in other words.

That will cover you for a lot of fishing scenarios, so don’t rush to build up your fly line collection. Get used to the floating line first. It will help you get comfortable with casting faster than any other.

Intermediate lines

As you gain in fly fishing confidence and expertise, you’ll notice that the floating line scenario described above could occasionally use some tweaks.

Retrieve a floating line with an underwater fly at the other end of your leader, for example, and the fly doesn’t travel back to you in a straight line. Because the floating line is on the surface as you retrieve it, the fly gets pulled upward, as well as toward you.

That can be good sometimes because if there’s a fish following it, the fly now looks like it’s trying to escape, which could prompt the fish to take it while still can.

If fish are in no mood to head to the surface, though, it’s an opportunity missed. Now you’d rather the fly stayed at the same depth under retrieve. You’d rather have an intermediate line.

An intermediate fly line sinks at one or two inches a second. It will slowly sink to the bottom if you let it. Retrieve it at the right speed, though, and it will effectively stay suspended at a certain depth, allowing the fly to come back to you in more of a straight line.

Intermediate lines are ideal for when you want to fish your fly just a few feet underwater. They also come to your aid when a lively breeze would otherwise blow an unhelpful bulge in your floating line on the surface. 

Not only does that bulge mess with your retrieve but it also means your contact with your fly is reduced. A fish could be trying the fly for size without you being any the wiser. Lying beneath the surface, however, intermediate lines are unaffected by any breeze. 

Slow-intermediate lines

A slow-intermediate line has the same dynamics as an intermediate line: it sinks slowly, it will be under the surface and if retrieved correctly it stays at the same depth. The difference is however that it sinks even slower than an intermediate line: at about 0.5 to 1 inch per second.

Sinking lines

No gradual sink with these bad boys. These are what you need when you just have to get your fly down deep asap. Their descent speeds range from three to nine inches per second and the latter variety is ideal when you’re fishing for bottom-feeding fish. The fast-sink line sits on the bottom while a floating fly hovers just above the floor at the end of a short leader.

Medium-sink lines are for when you want to retrieve a streamer at depth without the fly ascending through the water column. Also, when you are nymph fishing to fish that are several feet down.

Sinking lines are most relevant to lake, big river or saltwater anglers fly fishing very deep water. 

Their quicker descent rate compared to intermediates not only saves time but if you’re fishing in a drifting boat, you want to avoid a situation where your boat has caught up with your flies before the latter have reached the required depth.

Sinking lines are best left until your casting is fully grooved, as their weight can make them cumbersome to cast. There are however more and more sinking lines that have a similar dynamic to WF lines: the first part is heavier than the running line, making it easier to load the rod.

Sink-tip lines

Just as floating lines have their drawbacks, so do sinkers. Even lakes have their occasional currents and if your fly is beginning to drag, you can’t mend or reposition a sunk line to reduce the drag the way you can with a line lying on the surface.

Re-casting is also harder, as pulling a sinking line out of the water takes more effort than plucking a floating line off the surface.

The sink tip fly line is the necessary compromise. The name gives the game away – only the line’s tip (which is between three and 20 feet long, depending on the depth you require) sinks, while the rest of the line stays afloat.

They are also very useful if you're fishing from a bank where the first part of the water is shallow with lots of rocks, followed by a steep drop where you want to get your line down deep. A sink-tip line will enable you to fish in this specific scenario.

Fly lines and casting

A weight-forward (WF) fly line is made with the bulk of its weight at the front end, to optimize its casting range.

Once your casting becomes more accomplished and you need a longer cast (for boat fishing on a large lake, for example) you may want to consider other types of line.

Long belly lines

These are elongated WF lines. The ‘belly’ is the front end of the line where most of the line’s mass is found but it is longer than the usual 30 feet. 

Because of that, these fly lines travel further than conventional WF lines when you cast or roll-cast, but with a longer weighted section in play, you need to be a capable caster to get the most out of them.

Shooting heads

These represent another variation on the WF theme. Shooting heads increase casting distance by having a very thin running line (i.e., the rest of the line behind the weighted front end). This minimizes resistance as the WF section flies forward during casting. 

Mess up your cast, though, and shooting heads tangle more readily than conventional WF lines. Also, like long belly lines, their increased casting range leaves you having to detect bites and set your hook at distance, so the shooting head is another fly line best left until you are an experienced fly angler.

Double taper line

One for the river anglers, for whom presentation is key rather than distance. A double taper fly line’s weight is concentrated in its mid-section, while the long taper on either side of that mid-section encourages a gentler unfurling and landing of the line at the end of the cast.

To stretch or not to stretch

Some fly lines are now produced with minimal or no stretch or ‘give’ in them.

While some fly anglers are skeptical as to the benefits of such lines, they are designed for situations where maximum ‘feel’ is required.

If your fish is some distance away from you, for example, or it is taking the fly very delicately, the amount of give in a conventional line could leave you unaware of a take. With a no-stretch line, say manufacturers, that doesn’t happen.

If you are fishing for powerful fish that leave you in no doubt of their presence, on the other hand, you could be thankful for a line with some give in it, as it acts like a shock absorber. Catch those fish on no-stretch lines and there’s an increased risk that something will snap.  

Fly line maintenance

Fly lines don’t come cheap. Follow these tips to make them last.

While fishing

  • If your fly line is starting to look like a Slinky, thanks to the memory it acquires while wrapped around your reel, you can reduce the coiling by stripping it off the reel and wrapping it U-shaped around a pole or tree before gently pulling on the two ends to stretch it a little. Do not do this with low-stretch lines though: it could wreck them. If you have any doubts as to the stretchability of your line, contact the manufacturer.  
  • Any line stretching should be done before you fish, not afterward. Newly stretched line left lying on a reel for some time can contract and damage itself.
  • When pulling line off your reel to cast further, pull it forward, not sideward, so that it doesn’t keep rubbing against the reel casing.
  • Tempting as it is in your frustration, avoid brute force when untangling your line from waterside vegetation.
  • Try to avoid standing on stripped line while fishing. Repeated contact with the soles of your boots does fly line no favors. Consider using a stripping basket. 
  • Wash your hands thoroughly after applying sunscreen or insect spray. Some of their ingredients could damage your fly line.
  • When you snip off a leader make sure you don’t accidentally cut the fly line coating.
  • Clean any dirt and grit off your line between casts now and then. A dirty line can wear grooves into rod guides and those grooves further damage the line as it travels through them. If your line seems to be rattling against the rod guides as you cast, it may be ready for a wipe-down with a cloth or paper towel. Check the line occasionally for any cracks in the coating.

After fishing

  • Don’t put off tidying your gear for too long. Dirty line left on a reel suffers for it, especially if you’ve been ocean fishing. Saltwater can start eating your line within 24 hours.
  • Use specialist fly line cleaning pads or wash your fly line in warm water. Soak it for 15 minutes to loosen any dirt then wash it with mild hand soap (not detergents). Rinse it and lightly rub the line dry with a cloth. Check the line for any abrasions.
  • If you've been fishing in the salt and take a shower afterwards: take your reel with you in the shower. Unwind the line from the reel so that all the salt rinses off in the shower. Don't use soap though! Only water.
  • Fly-line dressing helps keep your line clean and protected but it’s probably best you pay for specialist dressing rather than making your own, lest any ingredients to see if they react badly with the plastics in your line.
  • The silicone content of fly-line dressing effectively re-coats the fly line and fly-line manufacturers often sell dressings that contain a cleaning and coating agent. Let the line dry afterward.
  • When drying fly line (or if you’re ‘hibernating’ it over the off-season) take it off the reel and hang it in loose coils – to minimize line memory – in a cool, dry place away from sunlight (ultra-violet rays damage the line’s coating.) But do have a way of identifying it so that you don’t forget its type or weight.
  • If it’s more than a nick and the line’s core is visible but undamaged, press the cut shut, wrap some fly-tying thread around the cut area of the line, then coat that area with a flexible glue.
  • Don’t practice casting on anything other than water or grass, to avoid damaging the line.
  • Practicing casting with just the fly line is a common but serious mistake. Add a section of leader with a piece of yarn tied on to represent a fly. The leader acts like a shock absorber. Practice without it and the tip of your fly line absorbs the energy transfer instead, causing it to weaken and break. 
  • Any doubts about your casting technique, book a casting lesson. A poor cast can over-flex and weaken your line.
  • Once you’ve got 250 fishing days out of a fly line, it may be time to replace it. If it’s a floater that no longer floats well or casts reluctantly even when clean, it’s done.
  • Don’t throw all your old fly lines away. Even if they are no longer any good for fishing, you can still use them for casting practice or if you teach others to fly fish. Small sections of pensioned-off line can also be ideal when you’re trying to get the hang of a new knot.

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