Line and Lure Weight Ratings

By Tom Kirkman, (RodMaker Magazine)

Here's a question from the September/October 1999 issue of RodMaker magazine:

"How do manufactuers and cutstom rod builders determine what line rating and lure weights are best for a rod? I have heard that factory rods are rated so that they will not break and cause costly warranty returns. Also, is there a correlation between line weight ratings for fly rods and spinning/casting rods (i.e., what line and lure weight would be appropriate for a casting rod using a standard graphite 9 weight fly rod blank?) Any light you can shed on this area of mystery for me would be much appreciated. . .Joe, Portland, OR

RodMaker Magazine

"Rods are usually designed around certain parameters such as the amount of weight the rod will be asked to load and cast with, and the amount of power that is desired for fish fighting. Good rod designers can easily deliver a blank or rod that will throw the required weight and hold up against the expected load. It is not the haphazard process which some fishermen have suggested.

Normally, line ratings are selected that provide a range of line tests that not only will work well with the blank, but stay below the rated breaking strength of the blank. In other words, the line should be the weak link in the chain, not the rod. Overlining a rod with a high pound test or line class breaking strength is not only unwise, but voids any warranty that the respective manufacturer has provided on the rod or blank. You see, as soon as you begin using a higher breaking strength line than what the particular rod/blank calls for, you have effectively make the rod the weak link in the chain. If something has to give way, it could then be the rod, instead of the line.

Finally, a fly rod is no different from a casting or spinning rod when it comes to casting. It is designed to load and cast with a specific amount of weight. The fly line number you refer to, correlates to a certain amount of weight, usually measured over the first 25 to 35 feet of fly line length. For future reference, here is the line rating to weight figures decided upon by AFTMA in the early 1960's.

2-weight - 80 grains/.183 ounce

3-weight - 100 grains/.229 ounce

4-weight - 120 grains/.274 ounce

5-weight - 140 grains/.320 ounce

6-weight - 160 grains/.366 ounce

7-weight - 185 grains/.423 ounce

8-weight - 220 grains/.503 ounce

9-weight - 250 grains/.571 ounce

10-weight - 300 grains/.686 ounce

11-weight - 350 grains/.800 ounce

12-weight - 400 grains/.914 ounce
~ Tom Kirkman

Publishers note:
If you have any tips or techniques, send them along! Help out your fellow rodmakers! ~ Publisher, FAOL

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