Fly Line, Backing & Reels 

     This angler is fighting a smallmouth directly from the reel   What is this knot?

Fly reels are made to hold a finite amount of "line."  This consists of the fly line, backing and leader together.  The amount of line a given reel may hold is referred to as its "spool capacity."   All reels will have such a "rating."  This rating is a direct relationship between the diameter of the reel's spool and its width.  Given the variation in these measurements in reels, there is a wide range of choices available in how much line a reel will hold.

A very small reel, with a spool diameter of, say, less than 3", and the narrowest of spool widths, may hold only a  fly line, of say 70', with no backing.  To the other extreme, a "big game reel", made for big fish in saltwater, may hold as much as 650' of line (a fly line of 80' & backing of 570'.)

A word about "backing": the purpose of fly line backing is to provide extra line length for large fish who "run into the backing"; it adds "filler" to the reel spool resulting in less "kinking" of the fly line; and it makes line retrieval easier due to the need for fewer rotations to return line to the spool.

Consult the tables   How to set up your reel

Most "reel tables" list reel/spool capacities based on the use of a weight forward (WF) fly line of a specific line weight and 20# dacron backing.  If a different type of line is used (such as a double taper/DT), or different backing is used (e.g., 30# vs. 20#, or gel-spun material in 30# & 45#), the specifications for how much backing will fit the spool will change.  Or, as happens more often than not, if you use a different line weight than that utilized to determine the capacity rating, you need to estimate what amount of backing would be needed.  To do that, use the following "rule of thumb":

  • if you go down a line weight (for instance, from #7 to #6) add 50 yards of backing . . .

  • if you go up a line weight, subtract 50 yards

How do I determine exactly how much backing to use?
this practice is needed only when you use fly line or backing that is
different than the manufacturer's specifications

Stated ratings for a reel's line capacity need to be adjusted for the wide variances in fly lines, their diameters & tapers.  To determine exactly how much backing is needed with any given fly line, you must temporarily fill the reel spool "backwards"; i.e., (a) wind the fly line on the reel first (b) temporarily tie the backing to the fly line (c) wind both up to within 3/8" of the line guard/cross braces (d) cut the backing to length. . . then remove the whole works & re-wind on the reel with the backing first (using an "arbor knot" for backing to spool) and then permanently tie the backing to the fly line (with a "nail-less knot") and again fill to within 3/8" of the top.

In order to make an informed decision on buying a fly line, you should be armed with the knowledge of the spool capacity of the reel you will use it with.

Armed with this knowledge, review the steps in Selecting a fly reel