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Technical aspects of

Pristine Products new "Double Furled™"

Fly line Extensions

(Nine Stage Tapered Furled Leaders)

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In an overly simplistic way, the mechanical aspects of fly fishing follow Newton's Second Law of Motion:

Newton's second law of motion can be formally stated as follows:

The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.



​​​​​​​​​​​​      Here we are looking at the force(F) that is applied to the fly rod, to accelerate(a) a given mass(m), which is the fly, tippet, leader and fly line outside the rod tip. Since the mass is a constant on a given cast, the greater the force the greater the acceleration, which means a longer cast.

      Taking a closer look at the mass(m), the total mass is a constant, but the distribution is not. It goes from a greater value at the rod tip to a gradually lesser value as we travel towards the fly. As the mass decreases, the acceleration increases, which is why the end of the fly line travels much faster than the line immediately outside the rod tip.

      A clear example of this is the bullwhip. A force imparted at the handle results in a faster acceleration as the mass(diameter) consistently decreases along the length of the whip, resulting in supersonic speed at the tip (the “crack”). Ignoring manufacturing difficulties, massive monetary considerations, and numerous other factors, the “perfect casting” fly line would taper consistently and uninterrupted from the rod tip to the fly - no leader, no tippet.


      Since in general we are looking to get the greatest distance and good line turnover based upon a given amount of energy applied to the rod, let’s look at where energy might be lost

(see Fig. 1) . First, internal friction in the unrolling fly line and air resistance are givens that we cannot control. Beyond this however are other areas of energy loss. Every time energy is transferred from one entity to another (rod tip to fly line, fly line to leader, leader to tippet, tippet to fly) there is an energy loss. The greater the transition differential and number of transitions, the greater the loss.

Furled leader energy loss

Fig.1- Energy Loss

Picture a garden hose, if you will. A new, leak-less hose will probably give a nice flow out the nozzle. But what if your hose is not long enough? Now add a much smaller diameter hose with a missing gasket to the end of the new hose and you’ll get leakage and a reduced flow out the nozzle (tapered knotless leader). Now replace the small diameter hose with a number of gradually reduced diameter hose sections, each with leaking connections, and again there will be reduced flow (knotted leader).

Fig.2- Leader Parameters

Furled Leader Parameters

      Our new “Double Furled”™ Fly line Extensions (Nine Stage Tapered Leaders) are designed to reduce these losses. The line-end connection is designed to be close to the diameter of the fly line. The furled leader is then smoothly, gradually and consistently reduced in diameter moving toward the tippet end. (see Fig. 2) These are not “disposable” leaders, but are rather designed to last for season after season. Additionally there are no knots to pick up moss, vegetation or debris.


      Our new “Double Furled”™ Fly line Extensions (Nine Stage Tapered Leaders) are constructed from very fine (thinner than your hair), carefully sourced fibers, selected specifically for use in our leaders. We do not use "thread". Thread is a finished product designed for use in machine or hand sewing, or for fly tying. It is generally tightly twisted and relatively thick. Since the first process in building a furled leader is twisting, this will either over-twist or un-twist the thread, depending upon whether it is "S" twist or "Z" twist. We also do not use fishing line. Again, this is generally too thick and stiff for our purposes.

What we do use are:

  • Filament (not "spun") Silk - raw and infused with floatant.

  • 4 mil (.004") monofilament in various color combinations.

  • 4 mil (.004") Fluorocarbon, specially treated to provide increased durability, flexibility, shock resistance, strength, abrasion resistance, and low memory.

  • Gel Spun UHMWPE - virtually unbreakable and naturally buoyant

How its made32.jpg
Furled Leader Construction

    We use the same fibers for our 9-12 wt. furled leaders as we do for our 3-5 wt.  leaders, just many more of them. This provides greater flexibility, virtually no memory, wonderful turnover and beautiful presentations (see Fig. 3). Many companies use fewer and thicker filaments for their heavier weight furled leaders, which obviously reduces material and labor costs, as well as performance. While they may promote how many "feet" of material are contained in their products, we speak in terms of "yards" (33 yds. to 210 yds.) in ours. For example, our 7 ft. 5-7 wt. furled leader is composed of 108 yards of filament.



furled leader to fly line connection for fly fishing leaders


Our guarantee is very simple:

      If you are dissatisfied with your furled leader for any (or no) reason within 30 days of purchase, return for exchange or refund (minus taxes, if any). If your furled leader fails while fishing during the first year of use, return for replacement or exchange. Return in the original package with proof of purchase.

Excludes abuse    Excludes commercial use.

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