Fly fishing is considered by many to be complicated simply because some of the fly
fishing gear and tackle appears to be complicated. Fly lines are certainly one of those
items that at first glance, appears to be complicated. A “WF8S” designation on a fly line
box doesn’t mean very much to a person just getting into fly fishing.
With normal casting or spinning tackle, lines are designated by their strength. They use
pound-test designations such as 6 pound test line, 20 pound test line, etc. The line is the
same size from one end to the other. That’s because when you cast you are casting a
lure or bait. It’s the weight of the lure or bait that propels the cast.
Flies weight little to almost nothing, depending on the type of fly. Fly line is tapered to
help propel the cast. You are casting the weight of the line, not a heavy lure or fly.
There’s such a thing as non-tapered fly line that’s designated as level fly line, but it’s
rarely used anymore. All the fly lines are tapered as follows.
The taper changes the size of the line at certain points to assist with the cast and
presentation. Weight forward line, the most common type, has a short section of larger,
heavier line than the main, running part of the line near the front part of the fly line that
helps propel the cast.
A shooting head fly line does the same basic thing. They have a section at the front end
of the fly line that is heavier than the main running line to help propel the cast.
Double tapered fly line has a heavier section located such that the line can be used on
either end. When one end of it gets worn, it can be swapped and the opposite end used.
It also has other advantages.
Fly lines come in different densities so they can float or sink at different speeds. Floating
fly lines are the most common. There’s both sinking tip fly lines and full sinking fly lines.
Sinking tip and sinking fly lines are used mostly for wet flies and streamers fishing deeper
water.
There’s all type of specialty fly lines. Some are designed and marketed for specific
species of fish such as trout, salmon, steelhead, bonefish, etc.