August 4th, 2003

The Premiere OnLine Magazine for the Fly Fishing Enthusiast.
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Observations on Fly Rod Construction
'The Case for the Solid Rod'
By Harry J. Briscoe
Hexagraph Fly Rod Co.

Just what does it mean when a fly rod is described as being, for example, a 9-foot, medium-fast, 5-weight? Technically, that description suggests that, with 30 feet (or some other prescribed length) of DT5 fly line extended beyond the tip, the rod will 'load,'... 'perfectly.' The description carries with it a surprising number of non-specific implications. What does 'load' mean? Or 'perfectly?' What does that imply if 20 feet, or 45 feet of line are extended? This essay is a layman's analysis of some of those implications and a suggestion that thoughtful fly fishermen may want to evaluate some alternatives.

The vast majority of fly rods available in today's marketplace are constructed of hollow tubes made of carbon fiber (universally called "graphite"). Flat sheets of carbon fiber fabric or other synthetic materials are rolled into a tube and heat-cured with a variety of scrims or resins to form the unfinished blank. The only alternative construction technique employed today for fly rods involves the cutting of tapered strips of a solid rod material and then fashioning of those strips into a rod blank. Wooden rods of bamboo (or "cane") have been constructed in this manner for over 150 years. The bending actions of hollow tube rods and solid rods differ from each other as a product of this difference in the manner of construction.

Graphite rod blanks gain their designed actions through the management of three principal variables; the materials that are utilized (the type of 'graphite' and the added scrims and resins), the design of the steel rod around which the material is rolled (the "mandrel"), and the pattern of the sheet of material (the "flag") that is rolled around the mandrel. The materials used these days are a variety of carbon fibers of varying modulus (stiffness), sometimes used in concert with other synthetic materials. The mandrel is a solid machined bar that itself has been cut into a predetermined shape, depending upon the length, line-weight and action of the desired rod. The sheets of graphite material are cut into a pattern, much like the pattern for a dress or suit of clothes is cut, again, by specific design for the given rod that is being built. The pattern takes a generally triangular shape with the base being broad, then tapering with a series of changing angles towards the thinner and longer tip. The flag is rolled tightly around the mandrel and then cured in an oven. The mandrel is removed leaving the resultant hollow graphite tube.

Few, if any, modern graphite blanks are built on uniformly tapered mandrels utilizing uniformly tapered flags. Since the flag is much wider at the bottom than at the top, rolling it into a tube produces a greater wall thickness in the butt of the rod than it does at the tip. As the flag is rolled around the mandrel, it rolls more times in the butt section and fewer at the tip. The overlap on the edge of the flag produces what is called the spine or spline. Since this line is a line of unequal thickness, the rod-builder must locate the spine and position it onto the top or the bottom of the finished rod. Thick walls are necessary in the butt sections of hollow rods for support (or lift), and thinner wall thicknesses are necessary in the tips in order to allow for adequate bending to create the desired actions. The non-uniformity of these design parameters produces a non-uniform bending pattern along the length of a given rod.

To address these inherent but necessary inconsistencies in the construction of a hollow blank, the blank builders actually "design-in" a desired formula for bending. The taper of the mandrel and the pattern of the flag are designed to create a preferred "load point" for the given rod. That point, by necessity, is generally somewhere in the tip section of the rod, the "faster" the action, the closer to the tip.

This specified design produces a rod that, in theory, loads "perfectly" with the prescribed amount of line. Our 9-foot, 5-wt., med-fast action, may, for example, be designed to "load" at a point 18 inches below its tip. Logic follows, however, that if the designed load point is "perfect", with say 30-feet of DT5 line, when the caster has applied just the "right amount" of momentum to the cast through his action, then with 45 feet of line, or with 20 feet, or any amount other than the designed-for 30 feet, it will load "less than perfectly." The rod will try to bend, load, and behave around its designed-in parameters, but it won't be "perfect." That is an inescapable mechanical fact. This is why the caster sometimes feels he is totally "in-tune" with his rod and line, and at other times he has to work harder to produce the same feeling. This is also why some "fast" rods just won't load at all with short amounts of line.

In addition to the imperfection in loading that come from rod taper design, hollow tubes inherently possess a second element that complicates casting. A hollow tube, when bent, flattens somewhat into an oval-shaped cross-section. This is simply a mechanical necessity, a reaction to the forces applied. The "top" and "bottom" of the tube in the plane of which the bending was applied take the stress of the bend, and the "sides" of the tube react to a lesser degree. This bending defines the plane within which that bent tube will perform most perfectly.

If a caster makes a back-cast and a fore-cast in exactly the same plane, he will be rewarded with a consistent reaction from the bending rod. If, however, the back-cast is made in one plane and the fore-cast in another, the rod will not be performing at its optimum, and the cast will be less than "perfectly efficient." With casts made in back and forward planes that are within 10 or so degrees of each other, this inefficiency, while present, may not be noticed. But, try a back-cast in one direction, and a delivery say, 45 degrees off, and you will see what happens. The bent tube cannot properly react to such a confusion of stresses. This is why most fly-casters find themselves false-casting their way "around a clock" when they want to significantly change the general direction of their cast.

So, despite, the apparent advantages and the popularity of tubular fly rods, their design still contains elements of mechanical shortcoming. These facts were not lost on the marketing departments of the major rod builders. The more "different" that individual rods are, one from the other, the more rods a fisherman will need to purchase for his own variety of applications. By making rods very specific, the manufacturer creates a requirement for the purchase of multiple rods.

A solid rod, built of tapered strips, addresses the performance shortcomings that are inherent in the hollow rod construction process. Cane, of course, is a natural material, and, as such, possesses inconsistencies of its own in the form of 'grain' and 'nodes.' Skilled cane builders work to lessen the affect of natural variations in their raw material. Today, the Hexagraph fly rod is the only other commercially available solid fly rod. Hexagraph utilizes a composite board made of carbon fiber laminated to an aeronautical construction foam from which are cut into long tapered strips. The strips are then constructed into a blank in a fashion much like that used for cane rods. The board is made of perfectly consistent and uniform synthetic materials. The strips are tapered at precise and consistent rates throughout the length of the rod. We use five or six different rates of taper to produce the various rods we build but, in each case, the rod tapers uniformly from butt to tip. This uniformity and continuity of taper produces a rod blank that bends uniformly along its length, depending only upon the amount of force that is applied.

When a fly-caster casts his rod, the rod is reacting to two elements that cause it to bend. The first is the effort provided by the caster himself, from slight to extreme. The caster applies momentum to the rod with the length of the stroke he makes and with the amount of force he uses in making the stroke. The second element causing the rod to bend comes from the line as it trails from the tip of the rod - the longer the length of line, the greater the force bending the rod. When these two forces (and the near infinite number of combinations of these two forces) are applied to a uniformly tapered solid rod, the rod responds "automatically."

Since the Hexagraph rod is tapered in a continuous and uniform manner, it will load - it will respond to the forces applied - at various points along its length, depending upon the magnitude of the forces. This response differs fundamentally from the manner in which the hollow tube rod responds as it attempts to load somewhere near that designed-in load point. With a short amount of line and a gentle stroke, the Hexagraph will load out near its tip, producing perfect and balanced deliveries. As longer lines are cast and as greater power is applied, the load point moves down the rod, with the continuous and uniform taper. The rod is actually a more versatile tool, capable of providing for the caster the combination of finesse and power that may suit the casting challenge of the moment.

Since the Hexagraph is solid, it will not deform in cross-section as does the hollow tube when it is bent. This feature allows a much greater variance in the planes the caster chooses as he casts. No imperfection is thrown into the cast with out-of-plane deliveries. The need for false-casting is radically reduced with the Hexagraph. Once the caster adjusts to the timing of the rod, and to the fact that he can actually manage the loading and the bending of the rod with the nuances of the power he applies, he can literally "pick-it-up and lay-it-down" in any direction and at any distance, merely by allowing the rod to do so.

The simple design of the Hexagraph also allows the use of several line weights on any given rod, dependent upon the casters personal preferences as to "feel," and upon the conditions of the specific application. Since the performance of the rod is not linked to a specific point along its length, a slightly heavier or a lighter line weight, which might be desirable on a given day due to the wind or the weights and types of flies to be used, will perform quite acceptably with the same rod - it will simply load at a different point along its length.

Because of the design of the Hexagraph, they are more full-flexing than are tubular rods. Since it is necessary for hollow rods to have relatively firm butt sections to support the active tip sections, they are necessarily "faster" in action than solid rods. This inherent stiffness has caused the casting stroke to evolve into its present form, which is generally short, crisp, and quick with exaggerated accelerations and sudden stops to send the line on its way. In fact, with many of today's "fast" rods, the caster does the work of bending the rod through his efforts in applying momentum through his arm and body, and the fly-line merely goes along for the ride.

Full-flexing rods, like the Hexagraph, depend upon the momentum and flow of the line to bend the rod, and then primarily upon the rod itself to unload or deliver the line. At the end of the day, the caster of a full-flexing rod will have done substantially less work than will the caster of the modern faster rod. The rod will have done more. When learning how to cast the Hexagraph, the contemporary fly-caster will have to pause a bit on the back-cast to allow the rod to load, and then will have to resist the urge to "drive" the forward cast too aggressively - it's more a matter of just "turning the rod over" with perhaps a gentle "push" to complete the delivery.

Much focus has been given in the marketing of modern fly rods to a journey towards lighter and lighter physical weights of the rods. To a degree, this may seem to be a desirable objective, but after a point, what, in fact, is the point? The advantage gained by the elimination of another half-ounce is often offset by the advent of new problems. Modern rods, being hollow and thin-walled are fragile. The new combinations of materials from which hollow blanks are rolled have improved somewhat the ridiculous fragility that existed in many blanks only a few short years ago, but breakage is still a major negative characteristic of tubular fly rods. Free replacement warranties have been the result, but the prospect of a free replacement 'next week' does not give one much solace when he is on the second-day of a two-week trip to some remote locale far from his dealer or factory. The current quest for lightness and increased durability (and the burden of the free replacement warranty) has sent prices for these hollow tubes to unbelievable levels.

Solid rods, by design, are much more durable than hollow ones. Although most marketing efforts are directed strongly to the contrary, a good case can be made for a moderate degree of 'heft' in a fly rod. As noted earlier, false-casting is frequently a required operation with hollow rods. The caster is either trying to find that balance point, or he is working his way 'around the clock' to change the direction (plane) of his cast. If a fisherman must false-cast two or three times for each delivery cast, he expends considerably more energy and moves more net weight than one who can pick his line up and deliver it with a single back- and fore-cast. He also spends less time with his fly on the water. Further, the effort to reduce rod weights by fractions of an ounce is immediately offset by the addition of the fisherman's favorite reel, the weights of which may vary far more widely than the rod. A balanced outfit with a degree of substance and stability in the rod, offers the caster much more in the way of 'feel' and feedback to the hand as the line flows throughout the cast, and that 'feel' provides critical information that allows the caster to be precise in his placement. In truth, rods that are 'too light' are, in fact, difficult to control.

Sometimes the way to take a step forward, is to take a step back. Much has been gained in casting and, in particular, in fly-casting through the advent and evolution of the synthetic fibers and compounds that are used in rod building today. That evolution, though, proceeded rapidly based primarily upon the quest for distance and power. In the last several years the market has recognized that touch, feel, finesse, and, most importantly accuracy, have improperly, and perhaps almost accidentally, been relegated to a second-class status. Many companies are now offering options of more full-flexing rods, and these options are being met with immediate acceptance by the market, but the mechanics of hollow tubes remain with some limitations. The performance that comes from solid and uniform construction techniques deserves continued attention. Some of the best promises for the future have their roots solidly in the past. ~ Harry Briscoe


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