Fly line backing is a term used in fly fishing that refers to a thin but very strong section of line that is secured directly to the arbor of a fly reel and to the back end of a fly line to provide an insurance policy of sorts on the fly angler’s otherwise limited tackle when hooking, playing, and landing particularly fast or strong game fish species.
Some game species like tarpon, steelhead, bonefish, and permit can run aggressively and for very long distances after being securely hooked with a fly. Bonefish and permit, the speedsters of the saltwater flats, can commonly run up to 200 or more yards during a fight with a fly angler. As most fly lines are only 100 feet in length, this makes a reliable and adequate backing strategy an important component of a fly angler’s tackle considerations before any trip.
Most trout fishing requires about 50 yards of 20-pound Dacron backing. Steelhead anglers like to use much more than this and are generally in the neighborhood of 175 to 200 yards of 20-pound Dacron (or a bit less if using stronger 30-pound test). Anglers chasing bonefish, permit, tarpon, and other large blue water game fish will often look to 200 or 250+ yards of 30-pound backing. These anglers will also be apt to choose gel-spun backing over traditional Dacron for its extra capacity.
What backing is made of…
Backing is generally available in one of two varieties, Dacron or gel-spun. The Dacron variety is made of tough polyester material called Polyethylene terephthalate (PETE), a synthetic resin developed for use in the construction of many of the world’s most common plastics; PETE is used to manufacture everything from soda bottles to spinnaker sails in advanced racing boats. Dacron is a trade name associated with PETE and can be spooled in long strands to create a tough synthetic line with a low coefficient of friction, making it perfect for fly line backing. Dacron is widely available in 20- and 30-pound test ratings and is the most commonly used and trusted type of backing in fly fishing.
Some fly anglers, however, have become partial over the years to the other main option in fly line backing: gel-spun backing. Gel-spun backing is constructed of another polymer called high-modulus polyethylene (HMPE), a material developed for use in body armor, ultra-safe climbing ropes, and high performance sailing lines. The polymer chains in gel-spun material give it extremely high break strength and a drastically decreased diameter, creating one of the major advantages of gel-spun backing over traditional Dacron: its unique ability to hold up to 75 percent more capacity over Dacron backing, allowing an angler to buy a HUGE insurance policy on the longest-running fish in the open ocean!
Backing should be attached directly to the arbor of the fly reel’s spool with a series of two or three simple overhand knots. Wind the appropriate amount of backing onto the reel using a motorized rigging tool or a manual line winder. When rigging a reel or spool with gel-spun fly line backing, it is extremely important that the backing be wound evenly about the arbor to prevent slipping and seizure of the backing during long runs that create heavy friction within the spooled material.
Once the backing is securely attached and evenly wound on the spool, the back end of the fly line is attached to the tag end of the backing. The strongest connection between the fly line and backing is with a spliced, double-nail-knotted braided loop and Bimini twist. This connection preserves nearly 100 percent of the each line’s unique breaking strength, while also allowing an angler to quickly and easily switch fly lines without having to retie any knots.
Technology continues and we at Leland have tested all the available backing options. In our opinion, there is now one clear winner. Hatch Outdoors (the maker of Hatch fly reels) offers a backing with clear advantages over both Dacron and gel-spun backing. With a diameter comparable to 12 pound Dacron backing, Hatch’s new backing has a break strength of 68 pounds. Unlike gel-spun backing that can literally cut into your fingers during a fish fight, Hatch’s backing is smooth and soft to the touch. Finally, Hatch’s backing is easy to knot and doesn’t require any special trick knots for connections. It’s simply the best fly line backing money can buy.