A casting arc that is too wide for the bend of the rod produces a wide loop.

The size of the casting arc must vary with how much the rod bends. When you rotate the rod butt through more arc than the bend needs, the rod tip keeps travelling up and over after it should have stopped going up — a convex, domed tip path the guide calls a dome, rainbow or windshield-wiper path. The fly leg follows the tip path, so it curves upward and the loop opens out wide. Over-bending the wrist is the classic way to get there: the wrist adds arc the rod bend does not call for.

Fixing it

• Narrow the arc until the tip path is straight again. This is the direct fix.
• Or increase rod bend — more force — to match the wide arc, but the guide notes that also increases line speed significantly.
• Read the fly leg to confirm: an upward curve means too wide, a straight leg means the arc matches the bend.

The written exam pairs this with the opposite fault: too narrow an arc for the bend gives a tailing loop.

Source

From the CI Study Guide (2025) (PDF), the Second Essential (the casting arc varies with the length of line past the rod tip) and the mechanics chapter’s rule that the arc must match the rod bend; Task 19 overhead faults; terms from the FFI Fly Casting Definitions.