Fly Lines and Backing Explained

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This is the most commonly used and important fly line density. The first choice for the beginner. It can be used for fishing dry flies on the surface, and nymphs, wet flies and lures below the surface.

Intermediate fly lines are designed to fish in the top layers of water. Effectively a very slow sinking line so if left long enough an intermediate line will sink to the bottom. Ideal for avoiding surface wake on calm days and in shallow water or to prevent surface drag on the line on rougher windy days.

Sinking fly lines come in a variety of sinking densities from slow sinking (di2) which sink at around 2 inches per second right through to the ultra fast sinking (Di8) line which sinks at 8 inches per second. A sinking line will help you get your fly down to the depth that the fish are feeding at. So the deeper the fish are, the quicker the sink rate.

The weight of a fly line is known as the AFTM rating and must be matched to the casting weight of the fly rod, you should find this information just above the handle of the rod with the rods length. Lighter lines from, say 1 up to 6 would be suitable for dry fly and nymph fishing on rivers and smaller still waters, lines 6 up to 10 will be suitable for sea trout and light salmon on larger rivers and trout fishing on larger stillwaters and reservoirs, lines 8 to 15 are suitable for saltwater and salmon fishing.

The fly line’s performance (presentation and distance) is achieved via the taper of the line and thickness of the weighted section of the line (see chart).

The most popular taper sold today and, as its name implies, the weight is concentrated in the front of the line with a thinner running line behind the thick weighted head section which is designed to shoot easily.

Although not as popular nowadays, they still have some followers. Tapered at both ends with a thick middle section, longcasting is difficult.

A shooting head is a heavy front head section of fly line, around 35ft long, which is attached to a thin stiff shooting or running line. Shooting heads are designed for extreme distance casting making them ideal for reservoir bank anglers who require extra distance. Shooting heads are becoming increasingly popular for salmon fishing and when used in conjunction with double-handed rods, incredible distances can be achieved with the minimum amount of effort.

Fly line backing comes in a variety of options, nearly all are braided, but utilise different materials for their specific use.

This is the most common backing and usually comes in Hi Vis colours so that you can easily follow the direction of a strong running fish. Normally 20lb is used for trout and 30lb is used for salmon and light saltwater – remember the heavier the breaking strain, the more space it will take up on the reel. 

This is a popular choice, as a shooting running line and its braided structure makes it easy to blind splice to a shooting head. It has a larger diameter than braided Dacron, which makes it a good alternative to Dacron on older regular arbour reels that often need a lot of backing to fill out the spool.

This hi-tec backing is approximately half the diameter of regular Dacron for a given breaking strain making it excellent for strong running fish in fresh and saltwater. Gel spun does require some specialist knots, so please ask our advisors for the best way to attach it to your fly line. The small diameter also makes gel spun perfect for adding extra backing to low capacity reels.


The first knot you're likely to be using and the most reliable knot for attaching backing line to the reel.


A great knot for constructing tapered leaders or leaders with droppers. It can be tied using equal or unequal diameter line and retains a good knot strength.

The Albright knot has proven to be the most popular and effective fishing knot for attaching different materials of unequal diameters.(backing to fly line or fly line to monofilament)

Also known as the Grinner knot, this is an extremely reliable knot for attaching flies, spinners or swivels to mono or fluorocarbon.

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