Probably no single thing has discouraged more would-be fly fishers than trying to cast a line that was incorrectly matched to their rod.

It is sometimes difficult for novices (and fishing tackle sales people) to realize the difference between fly fishing gear and other rods and reels. In fly fishing, the weight of the line is thrown, and it carries the fly to its destination. In other kinds of fishing, the lure is cast and it pulls the line behind it.

Fly line weight in relation to rod action is critical. Without the weight of the line, it would be impossible to cast the virtually weightless flies. Lines are made in a variety of weights to complement different fly rod actions.

A line that is too light for the rod makes it hard for a caster to feel it and won't flex a rod enough to put the rod action to work. One that is too heavy can be compared to trying to shake a cow by its tail.

The right combination however, can be astonishingly efficient. To an experienced fly fisher, a properly balanced line and rod is like having an arm long enough to reach out and gently place the fly fifty or sixty feet away.

The long and limber rod does become an extension of the arm as do the line and leader as they flow forward and unroll to drop the fly soundlessly on the water.

This relatively quiet presentation is one of the advantages of fly fishing. Adult fish found in shallow water are almost always there to feed, but because they feel more vulnerable with less water cover, the splashes that larger lure make will send them streaking for deep water.

The "splat" of a fly rod lure, however, doesn't seem to be alarming and instead often attracts feeding fish.

Other fishers, after completing a cast, must crank their lures back to the rod tip before the next throw. By comparison, the fly fisher can make a cast, then another and another while the hardware caster is grinding away to bring the lure back to the rod tip position before the next cast.

If a fish rises away from the path of the lure, a fly rodder can lift his fly at any time during the retrieve and place it where the fish is working. The spin or bait caster must finish cranking the lure back before casting again.

For all this to happen however, the fly fisher must have the correct weight line on the rod.

Anglers just getting into fly fishing cannot fully appreciate modern fly lines. The silk ones formerly used were pleasant to cast when conditions were perfect, but they had to be thoroughly dried at the end of each fishing day, and needed constant dressing which often didn't keep them from becoming waterlogged after an hour or two of use. Even the best ones were inclined to become gummy or sticky between seasons.

Modern lines will last for years with normal use, need little or no dressing and are available in an array of tapers and densities. These lines are built around a level braided core, usually of nylon and have a plastic coating which is varied with the weight requirements of the fly line.

Density is also so controlled by the manufacturer that lines can be made to sink at a prescribed rate, float, or do both. Some are made today that float for most of their length and ten, twenty or more feet of their tips sink. Some are fast sinking and some slow.

For those who remember when lines were classified by diameter, probably the greatest improvement is that controlled manufacturing now allows them to be designated by weight.

The weight of the front thirty feet (the amount of line in the air needed to "load" an average fly rod) exclusive of taper, is assigned a number. This system, devised by line manufacturers, consists of numbers from one to fifteen, each representing a difference of a specified number of grams in weight. Number one is the lightest and fifteen, the heaviest. Sizes lighter than three and heavier than twelve have limited availability at the present.

This number can be matched to the recommendation of the builder of any fly rod. Six, seven, and eight are the most popular weights and balance the majority of rods used today.

Most manufacturers include line recommendations in their rod specifications. However, because no two rod's blanks bend exactly alike, and some sales divisions think that specifying the lightest usable line adds class to their product, a manufacturer's recommended line may not necessarily be best.

Individual's casting style and physique also vary and play an important part in line selection, so sometimes a step lighter or heavier will perform better.

Line tapers are designated by DT, double taper; WF, weight-forward taper; and L, level or no taper. Whether a line is made to sink or float is indicated by adding S or F. For instance, a Double Taper, seven weight floating line would be labeled DT7F. DT7S designates the same taper in a sinking line. An L7F is a level (non-tapered) seven weight floating line.

Tapering a fly line to a small diameter at the end so it will lie out more delicately when cast is an old practice. Woven horsehair lines were constructed this way centuries ago.

Double tapers are simply lines that have both ends tapered so the line can be reversed and used longer.

A weight forward is one that has its casting weight built into the first thirty feet or so with a taper ahead of that. The remainder is of smaller diameter to help it slide through the guides easily. This is the one for longer casts where line shooting is important.

Level lines are the least expensive to purchase, are usually satisfactory in smaller diameters and are ideal under conditions where short back casts are desirable such as wooded streams.

Fly lines are relatively bulky, so monofilament leaders are used to make the fly to line connection less obvious. They are the last link in the fly fisher's "long arm".

Taper in a leader is important to achieving a delicate presentation of the fly. More so probably than line taper. One, properly designed, will unroll beyond the line and gently place the fly on the water with every cast.

Nine feet is a popular length, but ones as short as four feet and as long as fifteen are used. A good leader is stiff in the butt (about the same flex rate as the line), will taper slowly for about two thirds of its length and then slim rapidly down to a small diameter "tippet" in the last third.

The tippet should be of limp nylon to let the fly "swim" naturally. A leader that is too stiff for too much of its length will slap the fly down with a splash while one that is too limp won't straighten on the cast.

Tippet diameter is determined by fly size, not fish size. Too large will make a fly rigid on or in the water and too small will cause the leader to half-hitch around the fly when cast.

Floating leaders can cause fish-alarming shadows on a stream bottom. Wiping a little mud on a leader will make it sink.

Because fly lines are relatively bulky and the rods are flexible, hook points must be kept sharp to insure proper setting. An ignition point file makes an inexpensive, easily carried sharpener.

Leaders with curls from being wound on the reel also make hook setting difficult. Pull them through a tightly folded piece of inner tube or boot top to straighten.