Tackle Tips: Determining Line Weights

After about four months of switching rods, reels, and lines to suit a variety of spring and summer situations, some fly rodders are faced with a line or two that has no identifying line-weight marks.

If your arsenal is small, you probably know which is which or you can test-cast the unknowns to jog your memory. If not, a good scale comes in handy. You might have an old triple-beam balance somewhere under the bellbottom bluejeans in your closet or convince a local grocer to let you plunk a fly line down on one of those new-fangled digitals. Both will work, but they'll probably read back in fractions of an ounce, so you'll have to make a conversion because fly lines are weighed in grains. 1 ounce equals 437.5 grains, so we can come up the following saltwater line-weight table:

The Line Weight numbers are really a code, corresponding to the grain weight. There's about a +/- 10-grain window on the heavier weight lines, but most manufacturers are usually dead on the mark. However, don't expect the scale-weight to read back an exact match.

For one, full weight-forward fly lines are difficult to weigh because the rated Line Weight applies only to the working portion or thick, forward part of the line, not the front and rear tapers. What you'll have to do is try and weigh only the belly portion and the short front taper by holding the rest of the line your hand. This should give you a reading that's close to the standard rating.

Shooting Tapers are a little easier to weigh -- just put the whole line on the scale -- but this reading probably won't be dead on the mark, either. A grain isn't much, and you'll get a false reading if you've installed braided loop connectors, a permanent butt leader, or trimmed the head. Still, the overall weight usually falls within the +/- 10 window for the corresponding line weight.

Granted, you may find you'll have to use your best guess on some lines, but weighing your unknown lines can at least put you on the right track.

Avoid having to do this all over again by devising a marking system. This year, I started coding my lines with a series of blue and red bands of marking ink (blue for line weight, red for sink rate) [See: Tackle Tip #2] and protecting the marks with a light coat of Softex. So far, they're still quite legible.