Question about the fly rod and line weight system

[Bulldollyhuman]

I have a 3wt 10-foot nymphing rod and wf 4wt line works fine on this rod.

And have a 6wt 11-foot switch rod and people says wf 8wt line would be nice for this rod.

Two-handed system is relatively OK since I can estimate the combinations from the grain window of rod and gr/feet of the sink tip and shooting head.

Why are rod makers using this weight system? It's confusing actually

 

[jaredoconnor]

Conventional rods use the AFTMA standard, two hand rods use the AFTTA standard and euro rods don't seem to be based on anything at all.

I believe long, conventional, 3wt rods were what folks settled on in the early days of "euro nymphing". However, modern 3wt euro rods have relatively little in common with those. As you've probably noticed, a typical 3wt euro rod has a softer tip than a conventional 3wt rod. All my 3wt euro rods cast a 150gr Skagit line or 120gr regular line, so there is obviously some unofficial standard.

 

[Triggw]

We've just outgrown it. When the system was invented, it was all about casting smallish dry flies to trout at typical distances--30 feet or so. Now, techniques have become more varied and extremely specialized: streamer fishing, nymph fishing, big dries from drift boats, not to mention saltwater, two-handed, euro, etc. If a rod manufacturer designs a rod for a specific purpose, tuning it to cast a certain weigh in the first 30 feet may not serve that purpose. So there are a lot of variations. View the AFTMA standards as a starting place--it's better than nothing--and go from there.

 

[Wetswinger]

Using weight ratings in grain weights is simpler. Ignore the others, if possible, as rod and line manufacturers have manipulated the systems for marketing. Find your rods grain weight rating using their website or by calling the shop, and match it to the same rating on the line. Most lines show the grain weight in their literature..easy peasy...

 

[Evan B]

Conventional rods use the AFTMA standard, two hand rods use the AFTTA standard and euro rods don't seem to be based on anything at all.

I believe long, conventional, 3wt rods were what folks settled on in the early days of "euro nymphing". However, modern 3wt euro rods have relatively little in common with those. As you've probably noticed, a typical 3wt euro rod has a softer tip than a conventional 3wt rod. All my 3wt euro rods cast a 150gr Skagit line or 120gr regular line, so there is obviously some unofficial standard.

This is pretty much it, here (as far as Euro rods). When Euro nymphing, you're not loading the road for a cast in the same way as you do with a more traditional overhead cast. That rod is a 3wt in the top sections, and may actually feel lighter and more sensitive in that section than a standard 3wt since length will "soften" up an action. That same rod is closer to a 4/5wt in the bottom sections, however, and if you want to use it for more standard tactics with a weight forward line, you'd want to use a 4 or 5wt line to load the rod down in to those sections.