This game draws its own 3D. Your browser did not provide a WebGL2 context.
Air drives the sails, water resists the hull and keel, and your own speed changes the apparent wind. Steer with ←→, trim with ↑↓. There is a best trim for every apparent wind angle and it moves as you accelerate.
Also: flat water, steady wind, no current, no shear, no gusts, no shifts. The angles are the part to trust — every beat angle is a prediction and they land within about 2°. Full detail, and the per-item list of what is reconstructed, is in CREDITS.txt and under Help.
Stated up front because the deviations are large and you can see them on the screen. Boat speed is about +12% fast in very light air and +15% to +25% fast at high wind on wide angles. Equilibrium heel is much too large — 45° on a J/24 in 16 kn, 65° on a Melges 24 in 24 kn, against a real 15° to 25° — and the renderer does not clamp it, so what you see is what the engine computed. The published polar's high-wind roll-over above 20 kn is not reproduced.
All three have the same single cause: ORC equation 3.2's added resistance in a seaway and equation 3.3's four windage terms are not modelled, because each needs geometry a public certificate does not carry. The boat is therefore too fast, and the only fitted parameter available — the righting stiffness — absorbs that error by making every boat implausibly tender. The speeds come out right; the attitude does not.
What to trust: the angles. Every beat angle and every gybe angle is a prediction, and the beat angles land within about 2° of the published polars over four boats and nine wind speeds. See CREDITS.txt for the per-item list of everything reconstructed.