The Importance of the Casting Angle

The upstream angle changes throughout the drift. It is dictated at first by the cast, and then it changes with the movement of the flies. This angle is 0º when the rod is in front of the angler and perpendicular to the current. The U angle will be positive when the flies are upstream and negative when the flies are downstream from the angler’s position.

Control of the Upstream Angle U

The typical drift starts when the flies hit the water with a positive U angle, such as, for instance, 45º. Then the flies drift down at the mercy of the current, ending in a downstream position like, for instance, a U angle of -45º. Understanding what the effect of this angle is on the drag and lift will provide an important tool for drift control. When this angle is positive, the current will push the flies toward the angler, creating slack, and both drag forces and lift will be minimal. The further upstream the cast is made, the less lift and drag will affect the flies in the sinking phase. So, flies will have higher sink rate and go deeper with big U angles.

When targeting an area in front of the angler, the normal approach is to cast up-and-across to give the flies time to sink and get to the right depth when they reach the target area. The further upstream the cast, the deeper the flies will get when they are in the target area. You can vary the depth of your flies when they reach the target zone just by varying the U angle when casting.

Different drift attained with different U angles. When casting to the red point, flies get deeper in the lie, compared to the drift when casting to the black point. The smallest initial U angle (blue point) results in the highest drift in the water column

This is extremely important, because it will allow you to fish the target zone at different depths with the same rig just by casting at different angles (initial U angle). Also, it will allow you to fish deeper with light nymphs just by increasing the U angle. Conversely, if the flies are too heavy for regular U angles (45º), just use smaller U angles and the flies will reach the target zone at a shallower depth. This is very useful when moving from one stretch of water to another as it will enable you to minimize the number of rig changes. The control of this angle is also very helpful when facing situations with changing current speeds. Drag forces depend on current speed. The faster the current, the bigger the drag force. So, when facing fast currents, you can increase the U angle to compensate for the increased drag and get the flies to depth at the time you want. On the other hand, in slow currents you can decrease the U angle to avoid touching bottom early in the drift.

The ability to use the different upstream angles is key to mastering depth attainment. The angler must get used to selecting the right casting angle (initial upstream angle), using 60º, 45º, 20º, or even 0º to get the flies to depth in different water situations.