There is no way to find a perfect rod rating system for fly rods. Provocative statement isn’t it? But there are reasons why there cannot be an ideal situation. It does not mean that nothing is possible in this domain; it just means that this is not something that can be unique. There are rod scaling systems that reflect how rods are designed and cast by their maker. Individual systems from rod makers are not in the public domain; they are part of their intellectual property. The most popular ones are those that have been derived by independent people, striving to achieve a universal system. Let’s start with a historical review.
The oldest reference I found comes from a book published in 1946 by Joannes Robin. The author tried to rate rods using the classical horizontal rod with a weight at tip (around 150 grams). His work started in 1935 and he finally considered rating rods by the mass needed to get an angle of approximately 24 degrees between horizontal and a line joining the handle to the tip.
Interestingly, he tried to link this characteristic to the line he could cast but at that time fly-lines were classified by their dimensions not their weight as they are today. So he measured the weight of line he could cast! The corresponding line length was about 45 feet. At that time fly lines were still made of silk and quoted in diameters defined by a letter (example: HDH means a double taper with the diameter H for the belly and the diameter D at the tips). He finally gave up because of the difficulty in finding a clear fit but had just discovered the basic problem without successfully solving it. He only lacked of a little bit of knowledge in mechanics since he tried to evaluate rod stiffness and speed by complex combination of horizontal and vertical deflection under load, whilst there are other means of doing that experimentally (he designed a smart specific test bench for his experiments). A remarkable piece of work for that period, with little means in comparison to what we have available today.
This type of methodology can be qualified as a “relative deflection scale”. You imagine that, for a given line number, rods of various length would respond with the same weight applied at the rod-tip to reach the 24 degrees line. At first sight, this makes sense.
The second oldest system was published in 1948 and was inspired by the way used to rate spinning rods.
The ideal casting weight is 1/50th of the weight required to make the tip of a rod bend to the vertical position, with the rod clamped horizontally. For example, if you need 400 grams to achieve these conditions, your rod is supposed to cast 400/50 = 8 grams nominal. Spinning rods were quoted in grams, referring to the full weight (e.g. a 400 grams rod) by the middle of the 20th century. This may also have been used for fly rods but there is no evidence of that. As you can imagine, detecting the exact position for which the end of the tip is vertical is subject to uncertainty.
In comparison to J Robin’s method of rating, this scale does not need to take the rod length into consideration. It is an “absolute deflection scale”. We now have just reviewed the two basic methodologies but we cannot tell yet which one is the most appropriate.
A new line rating scale, based on the weight of the first 30 feet excluding the tip, was launched by 1961. Then line numbers appeared on the shaft of the rod and the discussion about if rods were quoted correctly took place. This scale, in weight, is more relevant since it is the weight of lines which influences the behavior of a fly rod during casting (more so than casting style), we shall come back to this point later.
Historically, Europeans took up the rod rating challenge first of all, when Dr Ludwig Rheim proposed his methodology in 1997. In fact he inspired what is known today as the “15 degrees” method and was based on a dynamic test when he presented it.
The 15 degree angle was the one he chose to release a load that corresponded to a 3.75 degree static test and then measure the time for the rod to cross the 3.75 degree line after release. Interestingly, it also refers to casting 45 feet of line. It was changed for a pure static test later, by Theodore Matschewsky, who realized he could match the dynamic values derived by Dr Rheim with static ones. There is a database of measurements with the specific calculations corresponding to the method (Theosky.com). The rods are also quoted in terms of range of speed.
The second method was published in USA by 2003.
William Hannemann (Dr Bill), developed his own from experience, starting from the observation that some people were not satisfied by ratings proposed by manufacturers, and that amateur rod builders needed something more practical. It is based on the principle that rods for the same line number have a 33% length vertical deflection if loaded with a given weight (using a small bag of US cents to tune the deflection, hence the name “Common Cents System”). There is also a database, which anyone can contribute to. Another parameter is given by the angle of the tip from vertical in the deflected position, the higher the angle, the more towards the “tip action side” the rod is. It is quite comparable to the 15 degrees method; the deflections are just larger than for that method. A close comparison would give 27% deflection for the “15 degrees”, 37% for the CCS (based on effective length), and 39% for J Robin’s methods. The CCS method includes some refinement on the dynamic side (CCF, F for frequency) in a later section.
Soon some casters noticed that “relative” methods are relevant for a small range of rod lengths, and that their prediction was not adequate for long rods, for example. This is due to the fact that, assuming that rods for a given line have the same relative deflection (%), short rods are significantly stiffer and long rods are significantly softer. Given the general trend between stiffness and speed, the scale tends to “underline” short rods, and “overline” long rods. Nevertheless these methodologies constitute some reference point and even if you do not believe completely in their ratings, you may just find what rating is best for you, for any line, and look for comparable rods.
Incidentally, some experiments had been conducted by 1996 in USA to compare rod characteristics and their rating. The stiffness measurement for small deflections appeared to be a good indicator of the adequate line number. The measurements were conducted by Jo Hoffmann (California Poly University) and his team, whilst Al Kyte, a renowned caster and casting instructor, did the ratings. At the end of a couple of days of experiments, it transpired that there was a pretty good correlation between the stiffness measurement for small deflections and the line ratings performed on various rods. Rod length (tested from 7”6 to 9”6, lines from two to eight) was not influencing that fit.
Apparently, this was not widely adopted whilst, in fact, comparable methods were in use by that period of time. I found one on the web, unfortunately without reference to its inventor. It may have been released in the late 90s but created earlier (peche-mouche-seche.com).
So why would this last technique, an “absolute deflection scale” be a more realistic fit? To understand that point we must refer to the basic mechanism governing the fly cast, which considers that a fly rod and line is comparable to a “spring and marble” system. In one case we rotate the rod, in the other we push on the bottom of the spring. Reality is more complex than in this simple model but the basics are interesting in a sense that the single characteristic explaining the behavior of the spring and marble system is a dynamic one. It is the “speed of the tackle”, or in more technical words the vibration frequency of the marble/line attached to the spring/rod. It means that one person may prefer a certain range of frequencies and others another one, obtaining similar results (line speed) for various rods and lines. Tackle speed is related to the stiffness of the rod and the mass at the tip: increasing the line number (mass) must be followed by an increase in rod stiffness to keep the frequency level in an appropriate range as the load is changing (with line length during the cast). So it is not by chance that a correlation between line number and rod stiffness has been found from experimentation because it comes from the underlying mechanism of casting. This was the subject of the last article about CCS (the CCF concept), but the author did not want to consider the mechanics of casting as relevant for his relative rating system.
Ok, we may have a clearer idea of what a rod rating should be, but why can’t it be universal? There are numerous reasons:
- First, the way we fish, our physical capabilities, our casting proficiency. I remember a friend of mine (wrist) casting his 9 foot Fenwick rod built for a #6 line with a WF3.
- Secondly, other masses (rod shaft, guides and wraps, line in the guides) also influence the speed of the tackle and contribute to the lack of universality.
- Third: the fact that rods are hard springs, increasing their stiffness as they deflect. This is a matter of design and it also contributes to scatter the rod/line fit.
Although imperfect, the current system is quite fair for rating rods, and it should be all right if you cast like the chief rod designer. If not, you know how you can adapt the line. This is cheaper than changing the rod.