AFTMA fly line standards - problems?
- why we now have a new AFFTA standard

fly lines for spey casting

AFTM – A Fictitious Tangled Mess? (written in 2003 prior to the proposed new standards)

Is the AFTM standard for fly lines being misused to the extent of causing confusing? The number on the packaging of new fly is understood to be the fly line rating according to a table agreed by the American Fishing Tackle Manufacturers (AFTM) in 1962. Despite that defined standard fly lines ratings appear to be in a bit of a pickle nowadays because some manufacturers do not follow the standard, instead they interpret it to suit themselves. Some of them believe that their interpretation helps the customer to choose the correct line size. This may be for a variety of practical reasons such as long or short line tapers that make the standard impossible to apply rigidity because they have a completely different weight distribution to the “standard” profile lines upon which the AFTM standard was based. So the question of line ratings has become complicated for the manufacturers and ultimately also for anglers.

The AFTM standard is based upon the weight of the first 30 feet of line, a length chosen because it represented the length of line at which a single handed rod should be suitably loaded for comfortable casting. For a long period after adoption of the AFTM standard fly lines had a front taper of between 8 and 10 feet (occasionally longer, maybe up to 12 feet) and therefore the standard was a reasonably reliable measure of the rod loading that the line produced. With confidence growing in the standard throughout fly fishing circles it was not long before rod makers picked up on line ratings and marked their products with them. It was quite common for rods to have two ratings and it was generally accepted that the lighter rating was the recommended double tapered line size and the heavier rating was the weight forward size. This made some kind of sense because the rod loading imposed by a DT line increased as the line was extended whilst the WF line belly (usually 38 to 45 feet for a single handed trout rod) comprised the majority of the mass and therefore limited the rod loading. Therefore in the practical application to fishing rods people accepted that more than 30 feet of line was frequently used. Rod rating may be just the maker’s opinion but the method has withstood the test of time because rods were tested and rated with lines that had tapers within the normal range of profiles.

That situation has changed; many of today’s lines have very different profiles and this lead to a different approach to line sizes because the AFTM system could no longer be directly applied. Instead manufacturers of longer tapered lines have turned the whole thing around. They couldn't’t decide how to rate their lines any other way so they picked up rods that had line ratings on them, cast the new lines and labeled them according to how they fitted the rods. Having developed this somewhat obtuse approach there is no prize for guessing what is likely to happen when a new rod is developed, the designer picks up a line of some sort, casts with it and marks the rod accordingly but since that line rating may not have been derived directly from the AFTM standard the whole thing goes to sixes and sevens (eights, nines …).

I spoke to an highly respected rod designer with many years of experience in the business and listened to his concerns on this matter. As part of his companies tests to determine rod ratings they weighed various lines and were shocked by the results, some lines were almost a whole size heavier than that stated on the packaging.

AFTM Fly Line Standards

Line “weight”







































For line weights higher than 12 add 50 grains to the previous weight.

Another prominent maker demonstrated a new rod, it was a two handed rod 12 feet long, intended for salmon and steelhead fishing and according to the designer it was rated #5. There is no way that a #5 line can carry a decent salmon fly and a rod of 12 feet rated for #5 line would be very soft indeed so I had serious doubts about the credibility of the claim. On examining the line I commented that it looked more like a #8 and the designer responded without blushing and said that it was his design of size #5 line! A guy who reviews tackle mentioned that he uses a particular type of line that weighs in close to the standard when reviewing rods and so he saw no problem with the system but obliviously he forgot about the many anglers who read reviews but use lines of different designs that behave quite differently. In some cases abuse of the AFTM standard is even more flagrant, for instance lines may be marked with two or three AFTM line ratings. A line has only has one mass measurement for its first 30 feet, according to the standard it can have only one rating! Salmon fishing lines are worst in respect of this confusion. Let’s consider a double handed #9 rod as an example, according to one line manufacturer it might be expected to balance a 9/10/11, 8/9/10 or 7/8/9 line, how confusing is that? For a minute we can suppose that the 8/9/10 line is perfect for the rod and consider what happens if either of the other apparently suitable line sizes is used. It seems likely that one will be too light and the other is probably too heavy so why put confusing numbers on the box in the first place if the line is suitable for a #9 rated rod? If the manufacturers can’t even figure out a line size is according to the AFTM system what chance has the angler got? My last example came from a friend who owns a tackle shop, I caught him playing around with a new 15 ft Hardy #10 Spey rod, and the line that balanced it was a Rio GrandSpey #7/8. I despair!

The problem with lines (especially salmon lines) arises from the definition of the AFTM rating based on the mass of the first 30 feet of line (excluding any parallel tip portion). Based on standard WF line belly and tapers this is a conservative amount of line for fishing even with a single handed rod. There have been ideas to change the AFTM system to suit double handed rods but two different line rating systems as abused at present would double the confusion and may conceivably lead to six different ratings being listed on the box! When rating rods I test them with a number of double tapered sizes lines and decide which rating they perform best with at a distance of about five or six times the rod length of line from the reel. I want them to be capable of making clean short casts easily and not easily overloaded at moderate distances. To avoid any confusion about line sizes I always use lines that comply with AFTM standards. Perhaps a solution to this problem could be that lines specifically designed for double handed rods should be based on the equivalent mass of a more suitable length of a standard double tapered line; say 60 feet of DT line because rod designers rate double handed rods using more than 30 feet of line anyway and doubling the length of line would be just about right. If such a standard for lines designed for double handed rods removed the confusion that exists it would be very helpful providing of course that multiple ratings for lines were not allowed. Sixty feet of #11 double tapered line weighs around 700 grains. That length one popular WF Spey line rated 10/11/12 weighs 1000 grains and consequently it feels very heavy on many rods. It’s only forgiving feature is that the 1000 grains represents almost the total weight of the line since the remainder is running line which is very light. In my opinion setting a standard at sixty feet would be long enough to incorporate sufficient of the fancy tapers that many of these lines have and which rendered the standard (30 foot) AFTM line ratings inappropriate for them in the first place.

AFTM page 2

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Copyright 2007 Alastair Gowans AAPGAI and FFF Master and THCI, APGAI. All rights reserved.