# Fly Fishing (ICSF Fly-Casting) — sourced facts
Every line carries a provenance tag and a URL.
Tags: DOCUMENTED | qualified (documented, but of something adjacent) | MEASURED | DERIVED | CALIBRATED | RECONSTRUCTED

## A. Governing body and events

A1 DOCUMENTED — The International Casting Sport Federation (ICSF) publishes
  "International Tournament Rules for Fly casting sport", Edition 01-2026, 24 pp.
  https://icsf-castingsport.com/resources/rules  ->  /download/file/CV1fQX80PA7MWCQSU7vETfcplW0KaCRxXimiT3PY.pdf
  (fetched 2026-09-15, 821487 bytes, sha256 recorded in tools-harness.js)

A2 DOCUMENTED — ICSF also publishes a SECOND, different rulebook,
  "ICSF_Competition rules 2026.01", which contains its own Event 1 "Fly Accuracy"
  and Event 2 "Fly Distance Single Handed" with DIFFERENT tackle and DIFFERENT courts.
  Same URL page, file HvxkYCnGobseUqOzJ9ZXnO4owY78AGQOCjHAuiXF.pdf (1678661 bytes).
  The two documents are both current (both 2026) and both are ICSF.

A3 DOCUMENTED — Flycasting events (rulebook A1, section IV):
  1 Trout Accuracy, 2 Trout Distance, 3 Seatrout Distance, 4 Salmon Distance,
  5 Spey 15,1', 6 Spey 16'/18'.

## B. Event 1 — Trout Accuracy (the game this app replicates)  [all DOCUMENTED, A1 pp.5-7]

B1  Rod: fly rod of any brand or AFTM class, maximum length 277 cm (9 ft = 274.3 cm).
B2  Line: Scientific Anglers Mastery Expert Distance competition WF5F, minimum length 35.50 m.
B3  Leader: monofilament, minimum length 2.50 m. Tip of leader min 40 cm long,
    max diameter 0.30 mm, highly visible, not transparent.
B4  Fly: standard tournament fly, floating, no hook, hackle diameter 16-20 mm,
    total length min 15 mm max 25 mm, min wire body length 13 mm, must float >= 3 s.
B5  Targets: 4 targets, each 3 concentric rings, diameters 60 / 120 / 180 cm.
B6  Court: targets placed about 90 degrees on the stand (fan form, 2 targets each side of
    the centreline), RANDOMLY between 8 and 15 m from the stand, measured from the front of
    the stand to the centre of each target. Stand is 1.2 m x 1.2 m, max 50 cm above water.
    Court extends 20 m in front of the stand.
B7  Start: overhead cast only. Fly in hand, fly line outside the top ring not longer than the
    rod (leader excluded). On the judge's signal the caster drops the fly, then begins false
    casting. Line may be stripped from the reel ONLY while false casting.
B8  Order: left to right, 1, 2, 3, 4 * 4 — a total of 16 casts.
B9  Scoring: hit within or on a ring: centre ring 5 points, middle ring 3, outer ring 1.
    Maximum score 80 points.
B10 Invalid (0 points): fly, leader or line strikes the surface or the inside of a ring during
    a FALSE cast; also 0 at the NEXT target if the caster lays the line down before moving on.
B11 Time limit: 5 minutes. Ties are broken by elapsed time.
B12 Allowed: hitting the water, or laying the line down, BEHIND the stand.

## C. Event 2 — Trout Distance (second game mode)  [DOCUMENTED, A1 p.7]
C1 Rod max 277 cm; same WF5F line as B2; leader monofilament max 3.00 m.
C2 Fly: yarn/wool, bright colour, min length 2.0 cm.
C3 Court: parallel sector 5-10 m wide, minimum 50 m long. Stand max 50 cm above water.
C4 Time: 6 minutes, divided into two rounds of three minutes.
C5 Score: casts measured from the stand to the fly, rounded down to the passed half metre.
   Longest cast defines the result; ties broken by second-longest, then third.
C6 Illegal (VI.3.g): in distance events, a cast whose fly lands outside the sector scores 0.

## D. ICSF world records (published by the federation)  [DOCUMENTED]
   https://icsf-castingsport.com/resources/world-records (fetched 2026-09-15)
D1 Trout Accuracy, Men:   72 points  — Steinar Rostad (NOR), WC Ahus, 2024.
D2 Trout Accuracy, Women: 47 points  — Anita Strand (NOR), WC Ahus, 2024.
D3 Trout Distance, Men:   40.5 m     — Bernt Johansson (SWE), WC Ahus, 2024.
D4 Trout Distance, Women: 33.5 m     — Tone Brathen (NOR), WC Ahus, 2024.
D5 Seatrout Distance, Men: 51.0 m; Salmon Distance, Men: 61.5 m; Spey 18' Men: 67 m.
D6 NOTE — the same table also lists "Event 2, Fly Distance Single Handed" at 62.04 m
   (Jan Weitz, CZE, 2026) under branch "Casting", NOT branch "Flycasting". That is the
   OTHER rulebook's event 2 (A2), which allows a 15.6 m / 38 g shooting head. The two are
   different events with similar names; the record table does not explain this.

## E. Fly line weight standard  [PRIMARY SOURCE OPENED]
E1 DOCUMENTED — "AFFTA Approved Fly Line Weight Specifications", 1 page.
   Live copy https://cdn.ymaws.com/affta.org/resource/resmgr/pdf_files/fly_line_weight_specs.pdf
   returns HTTP 403 AccessDenied. Opened instead via the Internet Archive:
   https://web.archive.org/web/2023/https://cdn.ymaws.com/affta.org/resource/resmgr/pdf_files/fly_line_weight_specs.pdf
   (31655 bytes, PDF 1.3, 1 page).
E2 DOCUMENTED — the table gives, per line number 1..15, LOW / TARGET / HIGH in grains and
   again in grams, and states "WEIGHT IS FOR FIRST 30' OF LINE MINUS LEVEL TIP".
   Line 5 (this app's line): 134 / 140 / 146 grains = 8.70 / 9.10 / 9.50 g.
   Full table is in js/linestd.js and is re-checked by tools-harness.js.
E3 DOCUMENTED — Wikipedia "Fly fishing tackle": the standard was originally established by the
   American Fishing Tackle Manufacturers Association and adopted by AFFTA.
   https://en.wikipedia.org/wiki/Fly_fishing_tackle
E4 DOCUMENTED — Wikipedia "Fly line" says instead that "the American Fly Fishing Tackle
   Association approved a weight standard" in 1960. https://en.wikipedia.org/wiki/Fly_line
   The two Wikipedia articles name different bodies; neither name matches the PDF, which is
   headed only "AFFTA". Recorded as an unresolved attribution, not silently picked.
E5 qualified — Wikipedia "Fly fishing tackle": typical fly line length 90 ft (27 m); leader
   usually 7-10 ft; leader tapers from about 0.020" to 0.010" (large fly) or 0.007" (size 14);
   fly line tip "usually more than 0.030 inch" thick. These are catalogue generalities, not
   a specification of the SA Mastery Expert Distance line, so they are tagged qualified.

## F. Literature actually opened  (abstracts/metadata only; full texts are paywalled)
F1 DOCUMENTED (abstract) — Spolek, G.A., "The mechanics of flycasting: The flyline",
   American Journal of Physics 54(9) 832-836, 1986. DOI 10.1119/1.14425.
   Abstract, verbatim in part: "As the cast line rolls out, the fly actually accelerates
   horizontally and seems to defy physical law. ... In the absence of air drag, the fly can
   accelerate to increase its velocity by an order of magnitude. Air friction dramatically
   decreases the effect, but some fly acceleration is still predicted. By tapering the flyline
   in various ways, the fly velocity history can be significantly modified, and some tapers
   are predicted to perform better than others."
   NOT OPENED: the full text. https://doi.org/10.1119/1.14425 returns HTTP 403.
F2 DOCUMENTED (abstract) — Robson, J.M., "The physics of fly casting", Am. J. Phys. 58(3)
   234-240, 1990. DOI 10.1119/1.16191. Abstract: "The physics of the forward motion of the
   flyline during a fly cast is discussed, and a computer model of this motion is proposed
   which reproduces the main features of this part of the cast." Full text NOT OPENED.
F3 DOCUMENTED (metadata only) — Lingard, S., "Note on the aerodynamics of a flyline",
   Am. J. Phys. 56(8) 756-757, 1988. DOI 10.1119/1.15464. No abstract is published in
   Crossref and the full text is paywalled: NOT OPENED. Cited only as evidence that a
   flyline aerodynamics note exists; no number is taken from it.
F4 DOCUMENTED (abstract) — Wang, G. & Wereley, N.M., "Analysis of Flexible Fly Fishing Rods
   and Casting Dynamics", ASME IMECE2003-43645, pp.675-684. DOI 10.1115/imece2003-43645.
   Abstract states a nonlinear finite-element rod plus a LUMPED-PARAMETER discretisation of
   the fly line, and that "The fly line loop generation, propagation, and line turn-over were
   represented numerically", and that rod flexibility must be included to capture the real
   dynamics. Full text NOT OPENED. This app uses the same class of model (flexible rod +
   lumped line), arrived at independently and then found to match.
F5 DOCUMENTED (metadata) — Anderson, D., Perkins, N.C. & Richards, B., "Quantitative
   understanding of the fly casting stroke through measurements and robotic casting",
   Sports Engineering 9, 97-106 (2006). DOI 10.1007/bf02844862. No abstract in Crossref;
   full text NOT OPENED.
F6 DOCUMENTED (metadata) — Ekander, H., Perkins, N.C. & Richards, B.W., "Development of a
   simulation model for fly casting and application to overhead casting", Sports Engineering
   28 (2024). DOI 10.1007/s12283-024-00482-4. Full text NOT OPENED.

## G. What no source decided (recorded, not silently chosen)
G1 The taper of the Scientific Anglers Mastery Expert Distance WF5F is not published anywhere
   this build could open. The per-section diameters and lengths used here are RECONSTRUCTED,
   then CALIBRATED so that the first 30 ft minus level tip weighs exactly 140.0 grains (E2).
G2 No source opened gives a drag coefficient for a fly line. C_dn is RECONSTRUCTED as the
   standard subcritical circular-cylinder value and swept over 0.8..1.6 in the harness; the
   headline conclusion is reported with that sweep attached.
G3 The fold/loop closure (energy-conserving smooth fold vs momentum/kink shock) is a known
   open question for folded filaments generally. This app does not assume one: the full
   discretised simulation is run and the reduced closures are fitted to it afterwards.
G4 ICSF rulebook A1 fixes target distances only as "randomly between 8 and 15 metres" and the
   fan only as "about 90 degrees"; the exact per-target angles are left to the organiser.