FFI’s Fly Casting Mechanics pages exist because instructors disagreed about some of the physics — so the FFI Fly Casting Mechanics Team publishes evidence-based reviews of the contested topics, each with a written article and supporting video.

Fly Casting Mechanics on flyfishersinternational.org

The topics under review

Does the anchor load the rod? The debate: whether the water-borne anchor of a roll or Spey cast actually bends the rod, or whether the rod loads only from the line the caster moves. Read the article in The Loop, Spring 2026 and the mechanics videos.

Is a fly rod primarily a spring or a lever? The debate: whether the cast is powered mainly by stored elastic energy released by the rod, or by the lever action of rotating the rod and hauling the line. Read The Loop, Fall 2025 — useful background for explaining mechanics to a student.

Terms and definitions. FFI Physics Terms for Fly Casting (The Loop, Summer 2025) is the physics vocabulary; the same terms appear in the current definitions.

Videos: Fly Casting Mechanics Videos and Mechanics Videos 2.

The Five Essentials — the version the exam uses

Bruce Richards’ Gammel’s Five Essentials Revisited (The Loop, Fall 2023, reproduced in the study guide) modernises Bill and Jay Gammel’s 1990 list against the current FFI definitions. This is the mechanics you have to be able to explain and demonstrate:

1. Straight rod tip path — what results when the other four are right; it produces the efficient, accurate narrow loop with a straight fly leg.
2. Casting arc varies with rod bend — match arc to bend, not merely to line length. Too wide gives a wide loop with an upward-curving fly leg; too narrow dips the tip and tails.
3. Power in the proper amount at the proper place — even, increasing acceleration through the stroke.
4. Minimum slack — the straighter the line at the start of the stroke, the more the rod can bend against line mass and the more efficient the cast.
5. A pause between strokes, varying with line length (and line speed) — too long or too short and slack appears.

Why this matters for the exam

• Written exam: casting mechanics is the first named topic, and the Five Essentials show up in the review questions for every task family.
• Performance exam: the loop standards (≤ 4 ft wide, straight fly leg, in-plane, similar front and back) are all consequences of tip path and arc.
• Teaching tasks: Task 20 (tailing loops) and Task 21 (30 ft → 50 ft adjustments) are mechanics lessons in disguise — Task 21 names the Essentials explicitly.