When I look at the amount of time and energy devoted on this very site (with good reason) to topics related to cartridges for rifles, or shells for shotguns, or arrows for bows, I cannot help but wonder why so few fly anglers carefully consider the line they use. Seriously, if anglers thought half as much about what line to use on their 5-weight as a shooter does about whether to fire 165-grain or 180-grain bullets through a 30.06, most questions about how to effectively cast would answer themselves. And a good fly line can make a budget rod dance, while crappy line will knock the performance straight out of the most expensive, next-generation graphite rod.
It’s one thing to decide whether you want a double-taper (say, for delicate dry-fly presentations) or a weight-forward line (a good all-around option), or a sink tip (for fishing streamers)—that’s the easy part. But even if you are looking at the most common line (the WF5F) it’s important to realize that all options are not alike. Different elements, such as coatings, core materials, and surface textures, all matter, and the line makers guard their manufacturing processes like you wouldn’t believe. I’ve seen rods and reels get made (and pretty much every fly fishing widget and gizmo) but I have never, ever seen the secret sauces and machines that go into making fly lines. And I doubt I ever will. It’s that big of a deal to keep those things under wraps.
That said, one aspect of fly lines always in plain sight is taper design. Fly lines are different than the monofilament, braid, or fluorocarbon used with conventional tackle in that they’re weighted. The weight of the line is what the angler leverages to hurl a very light fly, and the weight rating of a line, in general, is meant to correspond with the size rod it’s paired with. But where that weight is distributed in a line can make a huge difference when it comes to casting and fishing. For example, a line with all its weight packed near the front is going to generate energy to chuck flies, but a distance caster is going to want some weight reserved for the middle section, otherwise you’ll have to strip in all the belly, and then shoot on every cast to generate any length. Mending is critically important to an effective presentation, and some lines mend better than others. Again, if all the weight is bunched up like a bullet in the front of the line, and all you have to lift and move is running line, you won’t be able to mend as effectively as you would with some weight distributed farther back. If I’m turning over big streamers and making repeat casts at moderate or short distances (like banging the banks from a drift boat), I want that weight packed up front so I can lift and fire at will. On the other hand, double-tapers work well for dry-fly fishing with rods that are 4-weights or lighter, in particular. For most fiberglass rods, I still like weight-forward lines, but that’s just me.
It’s okay to go “off-label” too, but before you start “over lining” rods, realize that a number of very popular lines are already weighted one-half to one full weight more than the rod it’s supposedly made for. And some lines might say that they are made for a certain situation (and they well may be) but they certainly aren’t limited to that particular use. For example, I’ve found that some lines marketed for roll casting are actually some of the very best for forming tight overhead loops, provided your fishing is concentrated within 50 feet or so (where it should be on a trout river). A great roll-casting line can be an even better overhead casting line if you let it.
Of course, everybody’s casting style and fishing interests are different, so I’m urging you to play around a bit, and home in on the taper that’s right for you. Try some options your friends have that you don’t. Or most respectable fly shops will let you test cast different lines before you buy one. You should try different lines with at least the same diligence as you would test cast rods before buying one.
Trust me, I’m not falling for the marketing hype and saying that you need a different line for every situation you fish. I am saying, though, that there are legitimate differences in line tapers, and that the more you learn about them and match the right line to your own style and interests, the better you will cast and the better you will fish. Plus, you could even save yourself money if you currently think that a new rod, rather than a new line, will solve your casting woes.