Why Backing Is Necessary
The backing on a fly reel serves two fundamental purposes. First, it helps fill the reel with line, thereby increasing the size of the reel arbor, which not only allows more fly line to be retrieved with each rotation of the spool but also prevents the fly line from being wound into a tight circle, which tends to damage it . Secondly, it allows a greater length of line from which to play with any fish that may run a distance greater than the length of the fly line (typically 30 yards). According to the experts at Globally FlyFisher, fly lines are expensive, so it is a good idea to protect it with adequate backing.
Dacron Backing Material
Most fly reels come packaged with instructional material that tells the amount of backing material you should use. A braided dacron line is often specified as the preferred material, and the instructions often give the length of either 20-pound or 30-pound dacron backing the reel requires. Braided dacron is made of a polyester material and resists cutting into itself when would tightly on a spool. If there is a disadvantage to dacron, it is that, for a given strength, dacron is slightly greater in diameter than the other recommended backing material, which is made of a high-modulus polyethylene plastic.
High-Modulus Polyethylene Backing Material
High-modulus polyethylene backing material is often referred to as "gel-spun." With a higher strength per diameter than dacron, it is the choice of fishermen who regularly catch fish that can run out the line. The smaller diameter means that a much greater length of it will fit onto the spool. It is worth noting that the breaking strength of most fly lines is about 30 pounds, so you should use an equivalent weight of backing, unless the leader material is of a lower breaking strength.
Because braided dacron and gel-spun tend to be expensive, it might be tempting to use plain monofilament fishing line as a backing. This is usually not a good idea, because mono can tend to coil and tangle, and it also has more of a tendency to cut into itself when tightly spooled. It will, of course, work as a backing, but you should consider it only if it is certain that not all of the fly line will be paid out while fishing. You can also use old fly line as a backing. It has a greater diameter than the other backings, but, because it is only 90 feet long, it may not be sufficient to fill the spool.
Article Written By Garrison Pence
Garrison Pence has been a midwest-based (ghost)writer for three decades, taught university-level literature, and has written articles and white papers in trade publications of the Material Handling Institute, Engineering Today, Pharmaceutical, Food and Beverage Science, and Semiconductor. Pence holds a Bachelor of Arts in English and a Master of Arts in Literature.