Adhesion or Line Stick (Viscous Drag)

When a fly-line is resting on water the molecules of water enter the pores within the fly-line’s surface and due to the cohesion between these molecules and the molecules in the main body of the water this causes adhesion or line stick. The amount of adhesion on the fly-line, without taking into consideration the leader or fly, depends upon a number of factors:-

• How much surface area of the fly-line is in contact with the water (diameter, length, and buoyancy). The greater the area in contact with the water the greater the adhesive force. A sunk line will have a greater contact area.
• The material that is used to construct the fly line and its porosity. Slick line treatment reduces porosity and friction.
• Whether the water is still or running – or alternatively the fly-line is moving, which reduces the amount of cohesion.
• The ambient temperature and the water temperature.
• The straightness of the fly-line on the water. A randomly, snaking fly-line will create more resistance to lifting.
• Whether the fly-line is dragged or peeled off the water. Peeling means that only a small area is pulled off the water at any time and so the amount of force required is considerably reduced.
• The speed at which the fly-line is lifted because a faster lift will create more friction between molecules. A sudden release of the fly-line from the grip of the water will cause control of the line to be lost.

Therefore, when the fly-line is to be lifted off the water, initially it is important to peel as much of it off the surface of the water as possible. The speed of peel will be dictated by the ability to maintain tension on the fly-line; if it is too slow (slack) sag will occur and if it is too fast the fly-line will be released unexpectedly by the grip of the water and so control will be lost. The fly-line should be peeled at a rate which creates constant tension between the rod-tip and the water’s surface. In this way release from the grip of the water can be predicted. By simply tracking back with the rod-tip leading the fly-line it should be possible to place the fly-line wherever it is required to go with absolute precision.

When lifting the fly-line to perform the single-Spey or snake-roll casts it is very important to extend the peeling by initially sweeping the rod-tip into the bank and then out, in one continuous motion.

By slowly peeling, this should also straighten out the remainder of the fly-line that is resting on the surface of the water. It will also cause a sunk section of the fly-line to be pulled up closer to the surface level.

Line stick is desirable in Spey casting, where it is used to create an anchor, which holds the bottom leg of a D-loop firmly in place. In the case of an airborne anchor used in a single-Spey or snake-roll cast the anchor and D-loop are formed in a continuous movement and so the length of fly-line on the water has to be controlled to provide just enough resistance. However, casts that use waterborne anchors, such as the double-Spey and Snap family of casts, are made with two basic movements and are not continuous. Therefore, peeling the fly-line off the water is essential in these cases, if an efficient cast is to be made. Too much line stick will cause a cast to fail.

Single Spey Cast – Perfect Anchor Placement