Shuffleboard

Table shuffleboard

Two different games are called shuffleboard. This is table shuffleboard: a 20 ft 8 in maple plank, metal weights slid by hand, bands worth 1, 2 and 3 at the far end and a 4 for a weight hanging over the edge. The other is deck (or court) shuffleboard, played on a long court with discs pushed by a cue at a triangular 10-8-7 diagram with a "10 OFF" zone, and governed by the International Shuffleboard Association. If you type "shuffleboard" into a dictionary you will get the deck game — every major dictionary defines the cue game, and English Wikipedia gives the bare title to it. This app is the other one, the one in the bar.

How to play

Set the line and the speed and slide. The speed slider is calibrated in inches short of the scoring edge on a flat board — and the board is not flat, which is the whole point. Only one player scores a frame: whoever has the weight nearest the far end, and they score for every weight of theirs that is beyond the opponent's best. Space slides.

The board is not flat, and that is the game

A plank is deliberately dished across its width — a shade under a hundredth of an inch — to stop weights sliding into the gutters, and the bolts that do it are called climatic adjusters because hard maple moves with the humidity. A weight off the centre line is steered by the plank the whole way down. The engine models the surface as a real height field and the drift falls out of it; the closed form is

drift = crown × offset × distance ÷ (μ × half-width²)

so a slow board steers more than a fast one, which is what a player will tell you. On the centre line, and on a dead-flat plank, the deflection is exactly zero — not nearly zero, zero — and the engine's own test suite proves it bit for bit before it will build. The cross-section drawing in the panel has its height axis exaggerated, and says by how much, because a tenth of a millimetre cannot be drawn. The plank in the 3D view is drawn true unless you turn the exaggeration on under "The table" — the dotted ghost line is a real simulation of your shot, and the gap between it and the straight line of pips is the board's roll at true size.

The hanger

A weight overhanging the scoring end is worth 4 (rule 6.8.1.4), and it is judged by a "rub": an official slides a flat edge along the scoring edge of the board and if it touches the weight, it is a 4 (rule 7.1.3). So any overhang at all counts. Whether it stays up is a matter of statics, not of rules: a weight hangs while its centre of mass is still over the plank, so the greatest possible overhang is exactly half the weight's diameter — 1.15625 in, 29.37 mm — and exactly half of the weight is over thin air. The engine uses that criterion exactly and an independent geometric oracle checks it to a picometre.

Where the numbers come from

Every dimension in this app is quoted from the Official Table Shuffleboard Tournament Rules, 2024 Edition (1 February 2024), the numbered code published by the Table Shuffleboard Association and The Shuffleboard Federation for the game of Knock-Off, except where marked otherwise:

• 3.1.1 — the plank is 20 ft 8 in long, 20 in wide, about 3 in thick. The 22 ft every retailer prints is the cradle (3.1.2), not the playing surface.
• 3.1.1.2.1 / .2 / .3 — the 3-line 6 in from each end, the 2-line 12 in, the short foul-line 6 ft. There is no 1-line: the 1-band's back edge is the foul line.
• 3.1.2, 9.14 — the cradle about 22 ft by 31 in, 34 to 38 in high; the gutter about 5.5 in. Those two agree: 31 in less 20 in of plank is 5.5 in a side.
• 3.3, 3.3.1, 3.3.2 — the assembled weight 310 to 355 g; the puck 2.3125 in across and 0.75 in tall, widest 0.375 in from the top and tapered both ways, ±0.05 in; caps red or blue.
• 6.8, 6.8.1, 9.26 — only the side with a weight closer to the scoring end than any of the opponent's scores, and all such weights add up. 1, 2, 3 and 4 for a hanger.
• 7.1.2 — "The entire weight must be past the line for it to count as the next higher point value", judged from directly above, standing at the scoring end.
• 7.1.3 — the rub, quoted above. 9.17 — a hanger is over the END, not the side. A weight over a rail is not a hanger.
• 7.1.1.1 — a call that cannot be made is a "dead heat": neither weight scores, and only weights ahead of the dead heat are eligible.
• 9.33, 6.4.3 — a weight must completely pass the short foul-line to be in play, and one that does not is removed. 9.6 — a weight that leaves the surface is dead and scores nothing, even for the player who knocked it off.
• 6.3, 9.15 — turns alternate and the non-hammer side leads; the side that scores shoots first next frame and so gives up the hammer. 6.4.2 — 20 seconds a shot. 6.10 — there is no bust rule: overshooting the target simply wins.
• 6.4.6, 9.3, 9.5 — a blast shot on a clean board costs a point, which is why the opponent never plays one at an empty plank.
• 6.4.3.2.3 — a hanger that falls unstruck and is replaced becomes "protected" and cannot be out distanced. The engine's hang test is exact, so a resting hanger never falls on its own and this rule cannot arise in play — it is implemented and tested anyway rather than left out.
• 15 points comes from the 2018 edition's rule 5.1, "All games shall be played to 15 points". The 2024 code deliberately refuses to fix a number (6.1: "as defined by the event's criteria") and only assumes 15 inside its own worked example.
• The short foul-line regime — that a weight need only pass the line nearest the shooter, six feet away, making the 1-band 13 ft 8 in long — is the tournament default per the Shuffleboard Federation's Knock-Off page, which names both regimes. The 2024 code marks the line at both ends and never says which one rules 9.33 and 6.8.1.1 mean; that is its one real ambiguity, and both regimes ship here.

What is reconstructed

These are this app's own choices. No governing body specifies any of them, and saying so is the point:

• The friction of the wax. Rules 3.4, 3.5 and 6.7 make the Tournament Director responsible for the wax and the silicone spray, and comment that a board wants spraying "every 10 to 12 games of use" — so the code knows the surface speed varies and declines to quantify it. No coefficient of friction for a weight on a waxed plank is published anywhere. The three settings here put a full-length slide between three and six seconds.
• The amount of crown. Required to exist and be adjustable by 3.1.1.1, with no figure. The nearest thing to a specification is a feeler gauge, from a maker rather than a rulebook: McClure Tables says a correctly set plank lets a sheet of paper slide under a straightedge at the centre and not near the sides. A sheet of printer paper is about 0.004 in, so the presets here are of that order — and the conversion is an inference from the paper's thickness, not a number anyone published.
• The restitution between two weights, and the fact that they are modelled as frictionless against each other.
• The dead-heat tolerance. 7.1.1.1 gives a judge with a T-square, not a micrometer, so half a millimetre stands in for what a judge can separate.
• The rail's thickness outboard of the cradle — the only dimension of the table that is not quoted, because 3.1.2's 31 in is exactly the plank plus two gutters with nothing left over.
• How well the opponent plays, the colours of everything but the caps, the room, and the aiming aids. No rule governs what a player may look at.

What this is

An independent reimplementation of table shuffleboard, written from the published rules. It is not affiliated with, endorsed by or connected to the Table Shuffleboard Association, The Shuffleboard Federation, the International Shuffleboard Association, the National Shuffleboard Association or any table maker. Table shuffleboard is a folk game with no author: its ancestor "shovillabourde" was played for stakes by Henry VIII, and the modern table game standardised in twentieth-century America. The rules quoted above are theirs; the physics, the renderer and every reconstructed number are this app's. CREDITS.txt has the full list with the wording of each rule.

Differences from a real table, stated plainly: the two players shoot from opposite ends and swap ends each frame, and this app simulates every frame in one frame of reference rather than mirroring the arithmetic — nothing in the rules distinguishes the ends. Spin is modelled as decaying independently of the slide, which is an approximation worth about one per cent for any spin a hand can impart. The hang test is the rigid, flat-plank result; with a real crown a perfectly rigid weight and a perfectly rigid surface touch along a line and the problem needs the compliance of the beads and the maple. And there are no tournament officials, so nothing here is ever "made safe".