A major factor that contributes to the characteristic of the fly line other than its taper design is its ability to either float or sink. The materials that compose and surround the core of the fly line will cause the fly line to either sink or float. As a fly casting instructor it is important to understand the properties that make up the “outer skin” of fly line and its core, in relation to the mediums in which it is used, namely water and air. Generally speaking, water is the standard against which liquids are measured. Water is said to have a specific gravity. Specific gravity is the ratio of the density of an unknown substance to the density of a standardized substance. For our purposes the density of standardized substance is water. Water has a specific gravity of 1.0, against which the density of a fly line, (the unknown substance), is measured for its ability to float or sink in water. Density is simply the mass per volume of an object. If the density of the coating that surrounds
the core of the fly line is greater than 1.0, than relative to water,
the fly line will sink. If the density of the coating that surrounds
the core of the fly line is less than 1.0, than relative to water
the fly line will float. Relative to water a WF 7 floating line has
a larger diameter and a higher volume to mass ratio than a WF 7 sinking
line which has a smaller diameter and a higher mass to volume ratio.
Imagine two, 5 lb. tubes. One is made of cast iron and the other is
made of styrofoam. Relative to water which one will sink and which
will float? Which has the higher mass to volume ratio? Which has the
higher volume to mass ratio?
For a given line weight the density of the fly lines coating determines its diameter and the diameter of the fly line determines whether or not it will sink or float. Today’s WF sinking lines are made with powdered tungsten which has a higher mass to volume ratio (smaller diameter), than a WF PVC floating line, which has a higher volume to mass ratio, (larger diameter).
Hand a novice or intermediate caster 2 rods. One rod is rigged with a WF floating 7 weight line, the other is rigged with a 7 WF sinking line. After casting both setups most casters will automatically tell you that the 7 WF sinking line “feels,” or actually is, heavier” than the 7 WF floating line. But as we now fully understand, both lines weigh the same in accordance with AFTMA standards for weighing the fly line at the first 30ft. It’s only their diameters that differ.
The answer has to do with line taper and the dissipation of energy for varying line diameters when casting. All things being equal except for the diameter of the line, the larger diameter line taper generally speaking will dissipate more energy as the line straightens while the smaller diameter line taper will dissipate less energy upon straightening. This is yet another reason why smaller diameter lines for the same line weight, “kick”, as they straighten. Casting instructors, who understand this, naturally open up the casting stroke, or use a wider casting arc, creating a wider loop, allowing for greater energy dissipation and ease of handling. It is also important to note that smaller diameter fly lines of the same line weight penetrate wind better than their larger diameter counterparts, thereby creating less resistance to the wind, making them more efficient for casting in windy situations. The last characteristic of the fly line critical for an instructor to understand is the fly lines core. Without getting into great detail lets simply look at the stiffness of the core and its application to practical casting and fishing situations. Some cores are stiffer than others. Stiffer cores are better suited to hot tropical climates and remain adequately firm under an unforgiving tropical sun. However the stiffer core in cold water and or cold air will not cast smoothly as the line will lose most of its suppleness and becomes to stiff to cast efficiently.
The importance of understanding the composition
of the fly line is critical to an instructors understanding of how
to relate this information to an “advanced” student, who
may need to further their understanding of how certain variables in
the fly line will effect the casting and fishing performance of a
particular fly line in any given situation. Take the time to understand
and review this information and you will enhance your teaching abilities
as an FFF instructor and the casting abilities of your students. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
