Originally Posted by
Ray Kunz
How important is it, or should I ask what difference does it make, that you match your line weight to that which is recommended?
As a general statement, I believe that the line rating is the manufacturer's guide as to what line weight is best when casting 30 feet of line. More than that, it is my opinion that this holds for floating line and not sinking line; since I believe that sinking line casts differently than floating line.
I also believe that the manufacturers consider the action of the rod when making that rating. For example, I think that they rate a slow rod differently than a fast rod so that they want the slow rod to bend more deeply for the 30 feet of line than the fast rod. So I think line rating is an opinion rather than a science; and considers both the absolute of 30 feet of fly line mass and also the more variable style of casting with which that the rod performs best.
I think most everyone would agree that line rating is a guide and not an absolute and that what is most important is your personal "line rating" for that fly rod.
Originally Posted by
Ray Kunz
It seems to me that if you go a size lighter you would load the rod the same with a little more line length and visa-versa. Am I off base here?
This is generally true but not in ALL cases. It depends on how we cast and how we release the line through our fingers.
This would be true IF the velocity (V) of the different lines lengths were identical. What loads the rod is kinetic energy (KE) of the cast stored as Potential Energy (PE) in the bend of the rod. Simplifying this we can think of the line rating as the answer to the question, "What casting energy bends the rod so that it feels best with 30 feet of fly line?" The line weight (mass) that creates this feel is the line rating for that rod.
The problem is that the rod bend varies with the line velocity more than the line mass since KE = (M)(V)(V)/2. The rod rating is the line mass; but it totally ignores line velocity, which is much, much more important than mass. It is like describing a persons stature by his weight alone without giving us his height also.
For KE, line velocity is a square function and line mass is a linear function of energy. So we are using only one of the variables of casting distance to describe a specific line mass for a given distance. And that variable is the less important one.
This means that an increase in the line velocity affects the feel of a rod more than the same increase in mass. This means we can get the correct feel with a shorter amount of line with a relatively small increase in line velocity.
To shorten a cast with excess velocity, all we need to do is to scrub off some of that velocity during the final casting stroke so that the cast actual is shorter than the energy we put into the cast.
We also know that casting distance varies with loop size so that less energy is required to cast a given distance with a tight loop. But again loop size is not a variable in the determination of what line is right for a 30 foot cast. I assume that the manufacturers are using proficient tight loop caster to rate their rods so that it takes less of a rod bend for them to cast 30 feet than an intermediate caster. Again, if you are not in sync with the rod raters, the rod may not feel exactly right for you with the energy you need to make that 30 foot cast.
All of this technical mumbo-gumbo is to illustrate that the rod line rating is not an absolute but an art.
If I understand the the CCS or Common Cents System correctly, it is a static test whereas casting is a dynamic test. So the CCS system is best, I believe to compare rod blanks to each other and not to say absolutely that a given blank is a certain line weight blank for an individual caster. Nevertheless, I think is a valuable way to measure rod blanks against each other and is a reasonable way to approximate rod line rating.
Regards,
Silver
"Discovery consists of seeing what everybody has seen and thinking what nobody has thought"..........Szent-Gyorgy