Can someone help me understand why a rod is fully loaded when it's deflected 1/3 of it total length, shouldn't it vary by action and material? The AFTMA uses this constant.to reach a conclusion on overall rod weight. I think common sense said there is a direct relationship between IP and rod weight. For example, it takes a greater distance to load a slow action rod so wouldn't that also mean two things. More force and more time so a greater max potential?

Most likely because you have to have a standard from which to obtain relative measurements. But it should be noted that AFTMA doesn't have standards for fly rod line weights, only for fly lines.

Dr. Bill Hannaman did a great deal of research into why he chose a deflection distance equal to 1/3rd of a rod's total length as being "fully loaded." And this takes into account the rod's action since you are not deflecting per a standard amount of weight and then measuring the distance, but rather using a varying amount of weight to achieve the required deflection amount. Hopefully you can see the difference this results in.

You can find Dr. Hanneman's research, data and conclusions in the Volume 6 #2 issue of RodMaker.

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Why would it take a greater distance to load a slow action rod? Ultimately you have to have a constant to compare all rods to, or you're wasting your time. A quick story, I was building a manifold for testing Cummins engines. Field techs need something to evaluate equipment that can't come to the shop. It had five valved points you could attach different types of gauges to, one valved point had a pipe tee in it that was plugged off on one side and had a size N drilled hole in it, later I asked an enginneer why an N sized hole? He shrugged and said it was the only sharp bit they had at the time. It made no difference if everyone used the same test manifold.



Edited 1 time(s). Last edit at 03/09/2020 03:03PM by Spencer Phipps.

Lacking the magazine I should perhaps point out to the OP that in Dr. Hanneman's research he had loaded different rods to an optimum amount and then plotted points for each on a graph. Once he had enough data points he collected them and average the distance and it resulted in a deflection distance that was equal to 1/3rd of the rod's total length. There is much more to the testing but you'll have to get the magazine for all the rest - far too much to go into in a simple forum post.

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Thank you for the response Tom and Spencer. Are you saying Tom because of the inconsistency in rod weights from rod makers that the AFTMA is just as speculative in it's line weights? I think I understand the need for having a standardized metric for all rods maximum performance points but Spencer, I believe I'm saying the rods have different potentials so therefore, slow action rods need to be grouped together but seperate from say fast rods. Maybe in car terms, I'm probably not going to measure the tow capacity of a motorcycle or the top speed of my pick up. I understand the measurement weight changes but the only reason I can come up with 1/3 of the rod being the point chosen as fully loaded on all rods would be the desire for perfect physics of the cast and not performance of the rod. That would create a ceiling for the rods function. Tom if you have a link to the article in RodMaker I would greatly appreciate it as I am greatly confused and probably just annoying.

AFTMA categorizes line weights based on the weight of the first 30 feet of line. Rod companies choose numbers for their rods based on the AFTMA line weight they intend to be cast on the rod, but not necessarily with just 30 feet past the tip. This is the problem with rod # weights. Every company may use a different casting distance for their proprietary rating (remember, any rod will cast any line at some distance). This is why if you take a dozen 5-weight rods from different manufacturers, they will all possess different amounts of power/stiffness. They'll all cast a 5-weight line but some may fully load with 20 feet of that line past the tip while others may not fully load until you have 45 feet of the same line past the tip.

You can do some reading here: [www.common-cents.info]

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The action only affects the tip of the rod, like powered rods will have the same amount of tension the blank’s butt will have to contend with, looking at blank ratings in many catalogs you’ll notice the max recommended lure rating will be identical on fast and xfast blanks, just the lower limits change, the xfast will usually cast a lighter lure.

Matthew, what is the potential you refer to?

With fly rods at least "fully loaded" seems to depend upon the ability of the caster, not the equipment.

Phil, I believe I'm referring to the action angle (AA) and the Intrinsic Power (IP). In other words as close as I can gather to it's weight. I think coupled they give the rod it's overall potential. However it takes slow action rods a greater distance to reach potential. To me maximum potential would be the moment before a rod snaps under strain. Would a slow action five weight deliver equal force as fast action rods. This is assuming that both rods are made by the same company and therefore tested under the same guidelines. If that is the case wouldn't one action be suited towards heavier lines. Like a slow action rod might have greater potential but it never gets utilized in the mechanics of fly fishing unless the fisherman we're to add more weight to the line and fly so that rod might appear overloaded even though it actually is not.

Then again, a slow action 5 weight and a fast action 5 weight would have to move the same weight of line the same distance to be considered equal. That being said, I don't think it changes the deeper question I'm trying to get to. Does it make sense to fish heavier lines on slower rods?



Edited 1 time(s). Last edit at 03/11/2020 02:12AM by Matthew Furman.

No. Lines needed to match the power of the rod along with the expected input of the fisherman. If you have two rods with equal power, but one is a slower action than the other, both will still cast the same line. The difference in action will have more to do with how the fisherman times his casting motion.

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Thanks again Tom,
So then what does it mean to overloaded the rod? If that rod bends beyond 1/3 of it's total distance, what happens to performance?



Edited 1 time(s). Last edit at 03/11/2020 01:56PM by Matthew Furman.

With fly rods distance is the critical variable. "Accuracy" not so much. A competent fly-caster will quickly compensate for any variations in the direction the rod casts due to the blank or the wind - unless the tip-top or the ferrules on the rod are loose. Rod designers/sellers must appeal to both 40' and 100' fly casters, who carry between 15 and 50 feet of fly line in the air in their false cast. These realities must be accepted and specified before an advertiser/blank builder can provide useful information to the fly-caster about rod bend, or rod speed, or much else.

Don't mistake the testing parameters and constants for actual casting.

I don't what you mean by "to overloaded the rod." If you do that you'll know it because the rod will have trouble keeping the line airborne, no matter what the caster does. It's not hard to tell when a rod is correctly loaded - casting is nearly effortless and the rod does most of the work. If you are under or overloaded, you will experience undue effort either to apply more load through your casting stroke, or to find that no matter what you do with your casting stroke, the rod just drags through the air with an almost impossible to control line loop.

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There isn't much future in discussing fly casting without including the rod, and the line, and the angler. The fly fisher who does not need to or want to learn how to fly cast more than 35 feet needs a much different line in weight and weight distribution than the guy who wants to be able to cast 75 feet with that rod.

Three elements determine the success of fly casting: the rod itself, the line, and the caster. Far as I can tell it's a waste of time to evaluate any one of these without considering ALL THREE elements. Proof? Hand a 3 wt. rod with a 12 wt. line to the world's greatest fly caster and measure the results - in distance AND accuracy - and that "soulful feeling" if you wish.

Hand a 12 wgt rod with a 3 wgt line to an expert fly caster and measure the results
Norm

Good plan.