How to choose a line for fly fishing?

How to choose a line for fly fishing?

The choice of a line adapted to your style of fly fishing is essential. This article aims to provide some basics on the characteristics of a line and their impact on the fishing technique.

Bristle characteristics

The bristles are essentially distinguished by:

- the type of material: natural silk made from … silk thread and synthetic silk (varieties of plastics and synthetic threads)

- their profile : it is the variation of their diameter all along the tang

- their weight : measured over the first 30 yards, i.e. 9.14m

- their density : more or less dense than water, buoyancy

Material type

The silks were for a long time only natural, made of natural silk thread, hence their name. A "natural" silk is made of several strands of silk thread braided and covered with a special finish generally not quite natural...

Synthetic bristles usually consist of a synthetic yarn core coated with a plastic material.

Synthetic lines do not require maintenance and exist in an infinite variety of characteristics corresponding to each use, even very specialized.

Natural lines nevertheless retain the advantage of a greater density, allowing them to work well in the presence of wind and allow landing and snatching with great discretion.

Silk profiles

The most common tang profiles today are:

  • The Double Tapper profile (double taper) or DT: this profile is tapered "in a rat tail " at both ends of the line which is generally about 30m long. This profile is easy to cast at short and medium distance (15m) because it is sufficiently “massive”. It lends itself well to the roll cast. It also allows discreet poses. Symmetrical it can be turned over to prolong its life. Often recommended to the beginner, it is nevertheless very comparable to a WF profile at the short distance (<10m) generally only practiced at the beginning.

fly line profile double tapper DT

  • The Weight Forward profile (“Weight in front”) or WF: this profile, also in 30m, has a spindle shifted 8 to 10m at the front followed by a ' running line ' of thin diameter. It facilitates long distance casts at the cost of a more brutal landing than a DT profile. The glide of the running line is essential for casting performance and is achieved by various means: texturing of the line or glide additives.
fly line profile weight forward WF

There are also Triangle Taper profiles with a very long offset taper (>12m) combining the advantages of a DT and WF. They also allow a long roll cast.

Shooting heads or throwing heads are very heavy short lines to which a long running line should be added. They are used for very long distance throwing.

Each brand tweaks these profiles a bit into variations looking for the improvement of a particular feature.

Finally, the parallel profile corresponds to a silk of constant diameter. It was the standard for the old natural silks and remains interesting for short distance fishing in dry or nymph. In fact, they are often available in short lengths of 12 to 15m. Note that this is obviously the profile of a running line or the back of a WF line.


The weight of a line is standardized by the AFTA (Association of Fishing Tackle Manufacturers of America) on the front of the line alone: ​​30 yards or 9.14m. For the most common values

  • Silk no. 2: 5.2 grams
  • Silk No. 3: 6.5 grams
  • Silk No. 4: 7.8 grams
  • Silk No. 5: 9.1 grams
  • Silk No. 6: 10.4 grams
  • Silk No. 7: 12 grams
  • Silk No. 8: 13.6 grams
  • Silk No. 9: 15.6 grams

The lines most used for fishing in France range from 3 to 8. Lines 3 to 5 are mainly used for river fishing. Those from 6 to 8 correspond more to lake or reservoir fishing. The weight of 5 is the most versatile.

Numbers 1 and 2 correspond to ultra-fine river fishing, especially in summer (low water). The highest weights (8/9 or even more) are more intended for sea fishing with very large lures.

The fly line weight must imperatively be matched to the corresponding number of the rod under penalty of not being able to cast correctly or of tiring the rod with too heavy a fly line. Each rod has its line!

A certain tolerance of +/- 1 number is nevertheless possible depending on the use and action of the rod. A fast and powerful rod will handle slightly heavier lines well. DT lines are heavier over their full length than a WF of equivalent number, so they may also work well with rods of a higher number than the line.

It should be kept in mind that a high number line allows you to cast bigger flies and better fight against the wind but is quickly tiring to cast.


Several types of silk exist with different density and therefore different buoyancy:

  • Floating silk (F): this silk floats naturally on the surface of the water. It is used for dry fly fishing but also for nymph fishing at shallow depths (< a few meters). It is easy to handle in throwing and snatching.

  • Sinking line (S for sinking): this line allows nymph fishing at significant depths (>3m). It exists in different descent speeds from S1 (e 4 to 7 cm/s) to S5 (from 15 to 30 cm/s). These lines are very tiring to cast.
  • Intermediate line (I): this line sinks very slowly and is an alternative to floating line for nymph fishing at shallow depths. Greased it can also float.

Choice of line by style of fishing

The few following basics can help in the choice by type of fishing that you can obviously modify and specialize according to your tastes:

  • Beginner : A WF6 or DT 5/6 synthetic floating line offers enough weight to learn casting while being very versatile.
  • Small to medium river fishing : a DT3 to 4 floating line will allow fine dry fly fishing at a sufficient distance with medium-sized flies. In these fine peaches, natural silk still has its place.
  • Wide river fishing : A good quality synthetic WF5 or TT5 floating line will allow you to cast your dry flies the required distance with precision, even in the presence of wind.
  • Reservoir and lake fishing : a WF6 to 8 line will allow you to cast dry flies, nymphs and streamers at great distance and to face the often present wind. A mid-weight S3 sinker line is a good addition for fetching fish deeper. A weight of WF6 is often sufficient and less tiring.
  • Fishing in fast waters (mountain torrents, etc.) : a natural parallel line or DT of number 3 is a good basic choice for fishing under the rod or at short distance. It has the important advantage for this type of fishing of not falling into the rod rings because its friction is stronger than synthetic. Choosing a DT profile will make it easier for you to cast to reach the bottom of some gourg…
  • Fishing with very big lures : Here you need a heavy 8/9 line. A very powerful rod and good casting training will save you from fatigue and disappointment.
  • Fishing in nymph with the wire : the silk is practically not useful. Only the long leader (up to 6m) and its tip (several m) came out. So leave your dry fly fishing line in your reel or lighten it by putting only wire!

Product related to this post

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A quality DT line at the best price for river fishing Floating lines are the most common for dry, wet or nymph fly fishing near the surface. Lines with the DT “ Double tapper ”...

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