How To Choose the Right Fly Line Weight February 16, 2015 – Posted in: Basics, How-To

How To Choose the Right Fly Line Weight

Let me begin by saying that rod manufacturers design rods for the average person to use under average conditions. So unfortunately, most fly fishermen use only one weight of line on their favorite rod.


Manufacturers know your rod may be used in a host of fishing situations, but they can’t judge your casting style and fishing skills. So when they place a recommended line number on your rod, it is implied that it’s for average fishing conditions. First, understand that you’re not going to damage a fly rod using fly line a little lighter or heavier than is recommended. Certainly, at times, the rod will fish better if different line sizes are used.

Match line weight to conditions




Weight and speed need to vary
Fly rods are designed to cast a particular weight of line — with a good bit of line speed. If you drop down a line size, you benefit in two ways. One, the line is going to alight on the water softer than a heavier line. Two, because it is not as heavy, it doesn’t develop as much line speed. A line traveling at high speed often comes to the water with a heavier impact than one that is moving slower. Even with a line two sizes lighter, you can still cast a dry fly or nymph far more distance than what is called for in delicate trout fishing situations. So you don’t hamper yourself at all by using a line lighter than the rod suggests. Best of all, you can now use a shorter leader, since impact on the surface has been lessened.






Heavier line is often necessary
There are situations where using a line heavier than the rod calls for will also aid in casting and catching fish, such as when fishing small streams for trout. Where pools are short and casts are restricted in distance, a heavier line can be just the right answer. For example, on many brook trout streams, the pool may be only 10 or 15 feet long and you are forced to use a leader that is at least 7-1/2 feet long. That means that only a few feet of your fly line — the weight that loads or flexes the rod — is outside the rod tip. When fishing where distance is very short and only a few feet of fly line are outside the rod tip, it is important to switch to a line that is heavier. For example, if you were using a rod designed for a four-weight line and had to cast most of the time at targets less than 20 feet, placing a five- or even a six-weight line on the rod would let you load the rod, and casting would be much easier.

This same principle applies when you are bass fishing in the southern swamps. Often, you are casting in small, winding creeks, or where there is a lot of brush immediately behind you. This also holds true when fishing the backcountry of Florida for snook, where you are close to the target and backcast area is limited. If you are using a rod designed to throw an eight-weight line and you’re fishing at 30 to 40 feet from the target area and the backcast area is less than that, a nine-weight line will permit you to cast much better because the heavier line will load up the rod and let it flex.

Heavily weighted lines, like the Wet Cel III or Uniform Sink +, can and should often be used in one to two sizes heavier than the rod calls for because, for some reason, a line one size heavier seems to improve distance casting. Try one and you’ll see what I mean.

Use shooting TAPERS for greater distance
Finally, consider shooting tapers (also called “heads”), which are generally used to obtain greater distance. When casting with normal line, if you cast well, you never hold just 30 feet of line outside the rod tip to get distance. Instead, you false cast with considerably more than 30 feet of line outside. When using a shooting head, try using one that’s a size heavier than you usually do and you’ll be pleasantly surprised at the distance you gain.

So don’t limit yourself to the standard guidelines given by rod manufacturers. Experiment with different line weights for special fishing conditions. You will be pleased with the results.