Comprehensive Fly Line Study at WCU

The coefficient of friction measures how much resistance a fly line encounters as it shoots through the rod guides — the lower the number the less friction and the greater the shooting distance with the same effort. The WCU friction test used a Pasco photographic timer with a 70-gram weight falling through time gates to measure COF precisely across 71cm sections of running line. Line coating quality is the primary determinant of COF — and the difference between brands is significant enough to measurably affect casting distance.

Specific gravity measures the density of fly line material relative to water. A specific gravity below 1.0 means the material floats. The lower the specific gravity number the higher and longer the line floats on the water's surface. For dry fly fishing and surface presentations, look for the lowest specific gravity available. Lines with specific gravity above 1.0 sink — intentionally in the case of sinking lines and unintentionally in the case of poorly manufactured floating lines.

Elasticity measures how much a fly line stretches under load — tested in the WCU study by stretching 150cm line sections with 25 pounds of force. More supple lines stretch more and develop fewer memory coils when pulled from the reel. Most trout anglers perform best with a stretch ratio between 5% and 6%. Tournament casters and subsurface anglers often prefer lower stretch for better loop face stability. Big-game anglers prefer greater stretch to absorb the shock of aggressive strikes. Line core — braided or solid mono — significantly influences elasticity and memory in cold weather. Avoid solid mono cores in cold climates.

Fly line tip sinking occurs when water absorbs into the tip of the fly line over time — degrading floatation and producing drag in the presentation. Many manufacturers now fuse a loop at the tip to prevent water absorption and provide twice the floatation. Mac Brown's preferred solution is the Dave Whitlock splicing method — using a #9 embroidery needle, pin vise, super glue, and emery cloth to create a direct splice between fly line and leader that eliminates the bump of a loop-to-loop connection entirely.

Yes — and the WCU study proved it with laboratory data. Coefficient of friction, specific gravity, and elasticity all vary measurably between brands and directly affect shooting distance, floatation quality, and memory coil formation. Mac Brown has been a Scientific Anglers brand ambassador since early in his guiding career — recommending their lines for the consistent performance data that supports their quality claims. The best fly line investment is the one matched to your specific fishing conditions and casting style.

Mac Brown developed the concept of textured fly lines during his comprehensive fly line study at Western Carolina University where he served as Associate Professor. The research findings on coefficient of friction, specific gravity, and coating quality led directly to the textured fly line concept — understanding how surface texture affects friction and line-to-guide contact. The textured fly line concept has since become standard across the industry, fundamentally changing how fly lines are designed and manufactured over the past 30 years.

The WCU fly line study tested Rio, Scientific Anglers, Cortland, Monic, and Airflo — using 150cm sections of the running line from 5-weight forward fly lines. The front taper of each line was also investigated though it proved difficult to test due to the varying taper differences among brands.

The friction test used a Pasco photographic timer model ME9215A with a time gate span of 71cm. A 70-gram weight was attached to one end of the line and fell through the time gates. The rollers had a circumference of 0.79cm and the top roller carried a weight of 39.5 grams — keeping the fly line in contact at all times as it shot through the gates.

Beyond coefficient of friction other important considerations include line diameter, stiffness, and how lines react to extreme temperatures. The inner core influences memory and coil formation depending on climate — cores are either braided or solid mono. Solid mono cores perform poorly in colder climates.

Most anglers choose lines with a stretch ratio between 5% and 6%. Tournament casters and subsurface anglers often prefer lines with low stretch. Big-game anglers tend to prefer lines with greater stretch to prevent early break-offs. Very heavy tournament lines behave like spaghetti and become difficult to maintain loop face stability when elasticity remains high.

The Dave Whitlock method for joining lines, connecting leader to line, and other applications uses a number 9 embroidery needle, a pin vise, super glue, and a piece of emery cloth. With practice the splice takes less than two minutes and eliminates the bump of a loop-to-loop or nail knot connection passing through the guides.