From when the fly-line is first peeled off the water until the launch point in the forward delivery, the fly-line must be kept constantly under tension, otherwise it cannot be controlled. There are some special casts which utilise slack line to achieve a desired effect, such as a negative mend but these are special cases and will be dealt with separately.
To achieve continuous tension the rod-tip must be accelerated at all times even though the rate of acceleration might only increase very gradually, in some instances.
Deceleration of the rod-tip will cause a loss of tension and the control of the fly-line, and furthermore it will result in the unloading of the fly-rod. If rapid deceleration occurs before the end of the casting stroke this will cause the rod-tip to track a concave path, which will result in a tailing loop.
Prior to casting the fly-line must be laid out on the water so that there are as few twists and turns as possible, otherwise when the fly-line is lifted this will cause slack in the fly-line.
To maintain continuous tension at the beginning of a casting sequence the fly-line must be held close to the surface of the water, so that there is no initial slack in the fly-line, and then the fly-line should be continuously peeled off the water until the line-stick can no longer hold back the fly-line. This will ensure that as much fly-line as possible is off the water and that there is a minimum amount of resistance caused by line-stick. At this point the fly-line can be easily lifted and led by the rod-tip to where the caster would like to position the fly-line. If the fly-line is lifted too quickly this will cause the line-stick to release the fly-line unexpectedly and the fly-rod to unload, thus causing loss of line tension and control.
During sweeping movements with the fly-rod and line it is also important to maintain acceleration and hence line tension. This means that the sweeps must be made in wide arcs ( all the way around the arc with no shortcuts) with the rod-tip leading the fly-line at all times. To do this effectively the full leverage of the fly-rod must be used for sweeping movements.
With the exception of special casts, at the end of the casting stroke a rapid deceleration of the rod-tip is induced by stopping the fly-rod abruptly. At the point of maximum acceleration, the fly-line is launched in the direction of the cast.
Sometimes, it is possible to maintain control after deceleration of the rod-tip and this is used to good effect in some Spey casts such as the Jump Roll, Circle ‘C’ and the Snake Roll, however to do these casts follow-through has to be employed to maintain tension on the fly-line.
Some instances where continuous tension is important are:-
- Lifting the fly-line off the water and sweeping round to set up the D-loop for a single Spey cast.
- Sweeping back and peeling the fly-line off the water when setting up the D-loop for a double Spey cast or a snap cast.
- Lifting the fly-line off the water and placing the anchor for a double Spey cast.
- Lifting the fly-line off the water for an overhead cast.
Below is an example of continuous tension employed in the second sweep of the fly-rod for setting up the D-loop, during a double Spey cast.