Single hand rods fly line standard
Posted: Sat Oct 12, 2019 1:23 pm
There are technical reasons which can justify the current confusion about fly lines numbering. The original table, created during early 60s is no more completely followed by manufacturers (e.g. a #5 line is quoted at 200 grains instead of 140 grains – Rio In touch outbound short). Many people blame manufacturers but let’s see why this has likely happened.
When the table was defined, fly rods were only made of cane or glass, and were pretty slow by comparison to actual graphite rods. About ten years later the first graphite rods appeared on the market and since they were made of a single modulus material, they were just on the high side of the speed range. Since the beginning of the 21st century, new stiffer graphite fibers are used and bring the tackle speed above the range of what was produced during the 60s/70s. A race took place for lighter and faster rods. Today some rods are as fast as competition ones. Such rods can be swung faster and allow reaching extra distance for fishermen (I do not speak about competition here). This race caused a change in fly line production and we saw the weight of line increase on average. Although there is a tolerance in the original table, it is hard to find a line in the lower range; they all have weights above the target of the standard.
In fact, the change for a higher level of mass is due to the rise in speed of some fly rods. We all have a preferred speed range for the tackle, and if the tackle appears too fast for us, we can use another line number to compensate for it, even if the rod was not intentionally made for that line. But this is not the only reason. If one wants to make a pretty fast rod, it becomes stiffer and reaching the desired speed means that the corresponding line weight must rise, even if that speed is of a high level. This is also due to the fact that the equivalent mass of the rod goes down as the rod is lightened. Conversely it is for example very difficult to make a soft rod out of a stiff material; you have to choose a material which is soft enough to limit the speed of the rod. This phenomenon brings the line weight upwards for fast rods, although rod manufacturers can take care of using part of the actual specifications to stay as close as possible to the standard.
There is another phenomenon which is directly linked to casting, and which translates into larger tolerances in mass for higher lines by comparison to the tolerances of the table, which go from +/- 10% for the lightest line down to +/- 2.7% for the heaviest. Why that? Was it a question of manufacture tolerances during the 60s? I do not know, but what should be considered here first is the variation of speed of the tackle with the line weight. For example, if I consider that a 1% speed variation is acceptable all along the scale, then that can mean 20 grains variation between the minimum and the maximum specs for the lightest line (the value is 12 for the current specifications), but by 100 grains for the heaviest (and not 30 grains like today). Just the other way around, you see? If I want to match the 12 grains range of the lightest line for the heaviest line it must come up to 64 grains, and not 30.
The actual carry in mass can also bring confusion. If you us a saltwater rod, you likely use a head, they range from 30 to 50 feet (web info). Imagine you want to use the weight of a 50' carry for a 30' head, you just increase the weight of the line for a given number when using the short head (see example at the top). In fact the reference length of the specification (30') should vary with the fishing conditions, but this is too much for customers. Just unpalatable.
The difficulty we are facing is a trend for a rise in line weights, and as I explained above, this trend comes from an increase in speed for some rods, increasing the available speed range of commercial rods. The slow to medium fast rods are suited for the actual line standards, but the fast to very fast rods need a rise in weight, maybe we can say they are 0.5 numbers above as a starting point. However, the range of weight corresponding to a given speed variation enlarges the spectrum and the heaviest line could be in the 0.5 to 2 numbers range above the actual standard for fast rods. This is annoying, I know.
Merlin
When the table was defined, fly rods were only made of cane or glass, and were pretty slow by comparison to actual graphite rods. About ten years later the first graphite rods appeared on the market and since they were made of a single modulus material, they were just on the high side of the speed range. Since the beginning of the 21st century, new stiffer graphite fibers are used and bring the tackle speed above the range of what was produced during the 60s/70s. A race took place for lighter and faster rods. Today some rods are as fast as competition ones. Such rods can be swung faster and allow reaching extra distance for fishermen (I do not speak about competition here). This race caused a change in fly line production and we saw the weight of line increase on average. Although there is a tolerance in the original table, it is hard to find a line in the lower range; they all have weights above the target of the standard.
In fact, the change for a higher level of mass is due to the rise in speed of some fly rods. We all have a preferred speed range for the tackle, and if the tackle appears too fast for us, we can use another line number to compensate for it, even if the rod was not intentionally made for that line. But this is not the only reason. If one wants to make a pretty fast rod, it becomes stiffer and reaching the desired speed means that the corresponding line weight must rise, even if that speed is of a high level. This is also due to the fact that the equivalent mass of the rod goes down as the rod is lightened. Conversely it is for example very difficult to make a soft rod out of a stiff material; you have to choose a material which is soft enough to limit the speed of the rod. This phenomenon brings the line weight upwards for fast rods, although rod manufacturers can take care of using part of the actual specifications to stay as close as possible to the standard.
There is another phenomenon which is directly linked to casting, and which translates into larger tolerances in mass for higher lines by comparison to the tolerances of the table, which go from +/- 10% for the lightest line down to +/- 2.7% for the heaviest. Why that? Was it a question of manufacture tolerances during the 60s? I do not know, but what should be considered here first is the variation of speed of the tackle with the line weight. For example, if I consider that a 1% speed variation is acceptable all along the scale, then that can mean 20 grains variation between the minimum and the maximum specs for the lightest line (the value is 12 for the current specifications), but by 100 grains for the heaviest (and not 30 grains like today). Just the other way around, you see? If I want to match the 12 grains range of the lightest line for the heaviest line it must come up to 64 grains, and not 30.
The actual carry in mass can also bring confusion. If you us a saltwater rod, you likely use a head, they range from 30 to 50 feet (web info). Imagine you want to use the weight of a 50' carry for a 30' head, you just increase the weight of the line for a given number when using the short head (see example at the top). In fact the reference length of the specification (30') should vary with the fishing conditions, but this is too much for customers. Just unpalatable.
The difficulty we are facing is a trend for a rise in line weights, and as I explained above, this trend comes from an increase in speed for some rods, increasing the available speed range of commercial rods. The slow to medium fast rods are suited for the actual line standards, but the fast to very fast rods need a rise in weight, maybe we can say they are 0.5 numbers above as a starting point. However, the range of weight corresponding to a given speed variation enlarges the spectrum and the heaviest line could be in the 0.5 to 2 numbers range above the actual standard for fast rods. This is annoying, I know.
Merlin