The elements of the static roll-cast are used at the end of all Spey casts and prior to this all movements are concerned with setting up the fly-line for this to be achieved. Hence in this respect the roll-cast is a very important cast but it has limited applications by itself. However, it is useful for straightening a fly-line or rolling up a sinking line prior to carrying out one of the other Spey casts.
By lifting the downstream fly-line straight up in front of the casting position, using a shotgun lift, then slowly sweeping the rod-tip out and round using the bottom hand, this achieves two things; the fly-line is positioned outside the casting line and so crossover is prevented and a D-loop is formed, which is used, together with a water anchor to load the fly-rod during the forward cast. It is essential that the D-loop and anchor are exactly 180 degrees opposite the direction of the forward-cast.
The hands and arms are now in the key position and raised ready to make the roll-cast. From this position the with the fly-rod remaining at the same angle to the water surface, the butt is pushed down and forward (like driving stake into the ground). This does two things; it drops the rod-tip to the straight-line path and also it starts a gradual loading of the fly-load. As the fly-rod begins to gain momentum the butt is moved forward using both hands (translation) and the rod tip begins to gain speed. At the end of the stroke the bottom hand is pulled into the body and this creates maximum rod-tip velocity (speed). Throughout all of these movements the straight-line path must be maintained until the stop, which provides a rapid release of energy causing the fly-rod to unflex with a transfer of the energy into the fly-line. The position at which the rod-tip stops is normally high in the roll cast because the power stroke is a short one.
Beginners often fail to allow sufficient time for the D-loop to form and so the fly-rod is not loaded to its full potential. Another common fault is to have the rod-tip outside the casting-line (fly-line too close to the caster) which inevitably leads to cross-over. If the stop is not high enough then the loop will roll out onto the water rather than straightening out in the, air and then falling onto the water.