Before anemometers were common, sailors judged wind by looking at the sea. The Beaufort scale is an empirical system that estimates wind speed from observed sea state and land effects, ranging from 0 (calm) to 12 (hurricane).

Force 4, for example, produces small waves with frequent white horses; force 8 brings moderately high waves and foam blown in streaks. The scale originated with Admiral Francis Beaufort in the early nineteenth century and remains in use for forecasts and logbook entries worldwide.

Modern reports often give wind speed in knots or meters per second alongside the Beaufort number. The scale still helps crews anticipate handling difficulties, spray, and the need to secure gear before conditions worsen.

• Empirical scale of wind force from 0 to 12
• Based on observed sea and land effects
• Still used in marine forecasts and logs
• Links visual cues to expected wind speeds