FFI Fly Casting Definitions

Updated: Jan 16, 2026

Introduction

These casting definitions are designed to help instructors and others with a serious interest in Fly Casting communicate more clearly with each other. They are not necessarily intended to be teaching terms, and we of course respect our colleagues’ right to use terminology they consider suitable for their students. This single set of definitions covers both overhead and anchored casts with all fly rods. Some physics terms pertinent to fly casting are provided as they may help provide a deeper understanding of casting.

The document is laid out in following sections and is followed by an alphabetical index of terms linked to their definitions.

• Fly Casting
• Loops
• Fly Leg Shapes
• Fly Casting Movements
• Rod Movements During Pause
• Casting Terms
• Casts and Techniques
• Physics Terms for Fly Casting

We hope you find it helpful.

Fly Casting

Using a flexible lever to move and unroll a weighted line to propel an artificial lure.

Loops

Loop

The shape a fly line assumes as it overtakes rod tip during a Fly Cast.

Fly Leg

The moving section of fly line in a Loop from fly to start of Loop Nose.

Rod Leg

The moving or stationary section of fly line in a Loop from rod tip to end of Loop Nose.

Loop Nose

The curved section of fly line at front of Loop which is transition between Fly Leg and Rod Leg.

Fly Leg Shapes

Straight Fly Leg

A Fly Leg where fly line and leader are relatively free from curvature from Loop Nose to fly.

Convex Fly Leg

A Fly Leg with a dome shaped configuration curving away from Rod Leg.

Concave Fly Leg

A Fly Leg which is not Straight and dips toward Rod Leg.

Trailing Loop

A Loop which has a Fly Leg which is not Concave, and crosses Rod Leg.

Tailing Loop

A Loop with a Concave Fly Leg, which dips towards and crosses Rod Leg.

Under-Running Loop

A Loop whose Fly Leg unrolls below its Rod Leg.

In-Plane Loop

A Loop whose Fly Leg and Rod Leg are in same plane.

Out-of-Plane Loop

A Loop whose Fly Leg and Rod Leg are in different planes.

Fly Casting Movements

Translation

A linear change in position of rod butt.

Rotation

An angular change in position of rod butt.

Casting Stroke

Rotation and/or Translation of rod butt sufficient to cause Loop formation.

Stroke Length

The distance moved by rod butt during Casting Stroke.

Casting Arc

The angle change of rod butt during Casting Stroke.

Stop

Deceleration of rod resulting in Loop formation.

Rod Plane

The surface traced by rod during a Fly Cast.

Rod Tip Path

The straight or curved path travelled by rod tip during a Fly Cast.

Tracking

The lateral path of rod tip during Casting Stroke.

Trajectory

The direction travelled by Loop relative to horizon.

Lift

Moving rod up to reposition fly line for next movement in a Fly Cast.

Follow-Through

Moving rod forward and down after Delivery Cast.

Timing

The moments in time when each casting action transitions into next.

Tempo

The rates of movement within a cast.

Pause

The time period between Casting Strokes.

180 Degree Principle (Aerialized Casts)

The intended Rod Tip Path and fly line are closely aligned both laterally and vertically with target at start of each Casting Stroke.

180 Degree Principle (Anchored Casts)

The Delivery Cast, D Loop, and Anchor are closely aligned laterally with target.

Rod Movements During Pause

Rod movements during Pause can be made through a combination of Rotation and/or Translation.

Drift

Moving rod tip in direction of current cast during Pause.

Drag

Moving rod tip in direction of next cast during Pause.

Creep

Drag which contributes to a casting fault.

Up/Down

Moving rod tip up or down during Pause.

In/Out

Moving rod tip in (closer to caster laterally) or out (further away) during Pause.

Casting Terms

Aerial/Overhead Cast

After initial Lift, aerialized forward and back casts are made until Delivery Cast.

False Cast

A forward cast followed by a back cast, both of which remain aerialized.

Overhang

The amount of running/shooting line outside rod tip during Casting Strokes.

Point P

The point where fly line suspended from rod tip first touches water.

Anchor

The fly and fly line/leader in contact with water at bottom of D Loop.

Anchored Cast

A cast whose back cast Loop passes underneath rod tip and forms an Anchor and a D Loop.

Anchor Position

The location and layout of Anchor relative to caster.

Skipped Anchor

A fault where an Anchor briefly forms and then prematurely leaves water while moving away from target before Delivery Cast.

Blown Anchor

A fault where an Anchor prematurely releases from water during Delivery Cast.

Piled/Crashed Anchor

A fault where an Anchor lands on water creating slack in fly line/leader.

Bloody L Anchor

A fault where an Anchor has some of fly line/leader positioned at approximately a right angle to remaining Anchor.

Level Line Drop

A fault in D Loop Sweep which causes fly line/leader to land flat on water.

Trunking

A fault where downward rod tip movement at end of D Loop Sweep results in an Anchor which is too long, with Point P behind caster.

Hooking

A fault where D Loop swings around and behind caster.

Connection Point

The fly line/leader or fly line/sink tip connection.

D Loop

A round shaped back cast Loop between rod tip and Anchor of an Anchored Cast. Also used as a generic reference to back cast Loops of any shape in Anchored Casts.

V Loop

A pointed back cast Loop between rod tip and Anchor of an Anchored Cast.

D Loop Sweep

A Casting Stroke which initiates formation of back cast Loop of an Anchored Cast.

Line Placement Move

A movement of rod immediately after Lift which results in fly line being positioned appropriately on water for subsequent D Loop Sweep.

Touch and Go Anchor Cast

An Anchored Cast in which fly line/leader first re-contacts water after Lift and D Loop Sweep.

Sustained Anchor Cast

An Anchored Cast with a Line Placement Move before its D Loop Sweep.

Downstream Anchor Cast

An Anchored Cast which in moving water places Anchor and D Loop downstream of caster, or in still water leaves them on same side of caster as fly line before Lift.

Upstream Anchor Cast

An Anchored Cast which in moving water places Anchor and D Loop upstream of caster, or in still water places them on opposite side of caster from fly line before Lift.

Circle Up

A circular and upward movement connecting D Loop Sweep and Delivery Cast with which caster moves into Key Position.

Key Position

The hand and arm positions from which caster begins Delivery Cast.

River Left / Left Bank

The left bank of river when facing downstream.

River Right / Right Bank

The right bank of river when facing downstream.

Casts and Techniques

Delivery Cast

The final Casting Stroke of a Fly Cast, which presents fly.

Mends

Manipulating fly line layout by rod movement after Stop on a Delivery Cast.

• Aerial Mends - Mending before fly line/leader lands on water.
• Water Mends - Mending after fly line/leader lands on water.

Shooting line

Increasing amount of fly line outside rod tip by releasing fly line after Stop.

Slipping line

Increasing amount of fly line outside rod tip by releasing fly line and moving rod either before or after a Casting Stroke.

Straight Line Presentations

Casting Strokes and/or Mends which produce a straight fly line layout.

Slack Line Presentations

Casting Strokes and/or Mends which produce slack line layouts.

Curved Presentations

Casting Strokes and/or Mends which produce a curved line layout.

Hauling

• Single Haul - Pulling fly line through rod guides during either forward or back Casting Stroke.
• Double Haul - Pulling fly line through rod guides during consecutive Casting Strokes, after returning line hand towards rod hand during Pause.

Continuous Tension Cast

A cast where continuous rod movement maintains tension in fly line.

Oval / Belgiian / Elliptical Cast

A Continuous Tension Cast formed by a relatively horizontal back cast Rod Plane which then transitions without stopping into a more vertical Rod Plane on forward cast.

Roll Cast

An Anchored Cast without a substantial change of direction consisting of a Lift, D Loop Sweep, Circle Up, and Delivery Cast in which fly does not leave water until after Delivery Cast.

Switch Cast

A Touch and Go Anchor Cast without a substantial change of direction consisting of a Lift, D Loop Sweep, Circle Up, and Delivery Cast.

Spey Cast

An Anchored Cast with a change of direction.

Single Spey

An Upstream Touch and Go Anchor Cast with a change of direction, consisting of a Lift, a fly line repositioning movement, then a D Loop Sweep, Circle Up, and Delivery Cast.

Double Spey

A Downstream Sustained Anchor Cast with a change of direction, consisting of a Lift and an Upstream Line Placement Move, followed by a downstream rod movement transitioning into a D Loop Sweep, Circle Up, and Delivery Cast.

Snap Cast

An Upstream Sustained Anchor Cast with a change of direction, consisting of a Lift, a Line Placement Move in which rod moves upstream and reverses direction downstream, followed by an upstream rod movement transitioning into a D Loop Sweep, Circle Up, and Delivery Cast.

• Snap C / Circle C / Circle Spey - A Snap Cast where Line Placement Move consists of rod moving upstream and reversing direction downstream in a rounded path.
• Snap T - A Snap Cast where Line Placement Move consists of rod moving upstream and reversing direction downstream in a relatively straight path.

Snake Roll

A Downstream Touch and Go Anchor Cast with a change of direction, consisting of a Lift with a circular movement towards target, transitioning into a D Loop Sweep, Circle Up, and Delivery Cast.

Perry Poke

A rod movement which directs slack fly line on water in front of caster approximately in line with target direction, and is then followed by a D Loop Sweep, Circle Up, and Delivery Cast.

Physics Terms for Fly Casting

We invite instructors and other students of fly casting seeking a deeper technical understanding to explore this Continuing Education resource developed by FFI Fly Casting Mechanics and Definitions Teams. Certification candidates are encouraged to make themselves familiar with terms which appear in their exams.

Speed

How fast an object is moving.

Velocity

Speed in combination with direction of motion of an object.

Acceleration

The rate at which velocity changes over time. It may be positive, negative, or zero.

Positive Acceleration

An increase in velocity of an object. Commonly referred to as Acceleration.

Negative Acceleration / Deceleration

A decrease in velocity of an object.

Constant Acceleration

Velocity that changes at same rate over time.

Constant Velocity

Acceleration is zero.

Force

A push or a pull on an object.

Torque

A force that can cause an object to change its rotation about an axis.

Mass

The amount of matter or substance that makes up an object.

Weight

The result of force of gravity acting on a mass.

Work

The energy transferred to or from an object, computed as force multiplied by distance over which it is applied.

Energy

The capacity of an object to do work. Forms of energy include:

• Potential or stored energy
• Kinetic or working energy, computed as half an object’s mass multiplied by square of its velocity.

Momentum

An object’s momentum is its mass multiplied by its velocity.

Impulse

The momentum transferred to or from an object, computed as force multiplied by time over which it is applied.

Power

A measure of rate at which work is done, or at which energy is transferred, computed as work done per unit of time.

Newton’s Laws of Motion

First Law of Motion: Inertia — An object will continue its current motion or lack thereof until some net force causes its speed or direction of movement to change.

Second Law of Motion: Force — The acceleration of an object is directly proportional to net force acting on it. Expressed as force equals mass times acceleration.

Third Law of Motion: Action/Reaction — For every action, there is an equal and opposite reaction.

FFI Fly Casting Definitions Team

Bryan Martin — MCI, THMCI and Bruce Williams — MCI, THMCI (Definitions Team Co-Chairs)

Sekhar Bahadur — MCI, THMCI Mac Brown — MCI Mark Huber — MCI, THMCI Bob Young — MCI

With thanks to FFI Fly Casting Education Program Leadership Team and our reviewers of fly casting definitions:

Tomonori (Bill) Higashi — MCI, THMCI Willie Holmes — MCI, THMCI Tim Rajeff — MCI, THMCI Todd Somsel — MCI, THMCI Mark Surtees — MCI

Special thanks to Bintoro Tedoriswoyo — CI, THCI for graphics and diagrams.

FFI Fly Casting Mechanics Team

Sekhar Bahadur — MCI, THMCI, Chair John Bilotta — MCI, THMCI Vince Brandon — CI Mac Brown — MCI Craig Buckbee — MCI Willy George — MCI, THMCI Tomonori (“Bill”) Higashi — MCI, THMCI Graeme Hird — MCI Lasse Karlsson — MCI, THMCI Malik Mazbouri — CI Bruce Richards — MCI Mark Surtees — MCI

Index of Casting Terms (Alphabetic Order)

180 Degree Principle (Aerialized Casts) 180 Degree Principle (Anchored Casts)

A

Acceleration Aerial Mends Aerial/Overhead Cast Anchor Anchor Position Anchored Cast

B

Belgian Cast Bloody L Anchor Blown Anchor

C

Casting Arc Casting Stroke Casting Terms Casts and Techniques Circle C Circle Spey Circle Up Concave Fly Leg Connection Point Constant Acceleration Constant Velocity Continuous Tension Cast Convex Fly Leg Creep Curved Presentations

D

D Loop D Loop Sweep Deceleration Delivery Cast Double Haul Double Spey Downstream Anchor Cast Drag Drift

E

Elliptical Cast Energy

F

False Cast Fly Casting Fly Casting Movements Fly Leg Fly Leg Shapes Follow-Through Force

G

Gebetsroither Cast

H

Hauling Hooking

I

Impulse In/Out In-Plane Loop

K

Key Position

L

Left Bank Level Line Drop Lift Line Placement Move Loop Loop Nose Loops

M

Mass Mends Momentum

N

Negative Acceleration Newton’s Laws of Motion

O

Out-of-Plane Loop Oval Cast Overhang

P

Pause Perry Poke Physics Terms Piled/Crashed Anchor Point P Positive Acceleration Power

R

Right Bank River Left River Right Rod Leg Rod Movements During Pause Rod Plane Rod Tip Path Roll Cast Rotation

S

Shooting line Single Haul Single Spey Skipped Anchor Slack Line Presentations Slipping line Snake Roll Snap C Snap Cast Snap T Speed Spey Cast Stop Straight Fly Leg Straight Line Presentations Stroke Length Sustained Anchor Cast Switch Cast

T

Tailing Loop Tempo Timing Torque Touch and Go Anchor Cast Tracking Trailing Loop Trajectory Translation Trunking

U

Under-Running Loop Up/Down Upstream Anchor Cast

V

V Loop Velocity

W

Water Mends Weight Work

Source: Fly Fishers International