Sea State & Wave Calculator
Estimate wave conditions from wind speed and fetch
Hours
Wave Conditions
Douglas Sea State
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Significant Wave Height
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Wave Period
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Wave Length
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Wave Speed
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Beaufort Scale
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Maximum Wave (1 in 1000)
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Sea Description
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Douglas Sea State Scale
| State | Height (ft) | Description |
|---|---|---|
| 0 | 0 | Calm (glassy) |
| 1 | 0-0.3 | Calm (rippled) |
| 2 | 0.3-1.6 | Smooth |
| 3 | 1.6-4 | Slight |
| 4 | 4-8 | Moderate |
| 5 | 8-13 | Rough |
| 6 | 13-20 | Very Rough |
| 7 | 20-30 | High |
| 8 | 30-45 | Very High |
| 9 | 45+ | Phenomenal |
Wave Formation & Safety
Wave Development
Waves develop based on wind speed, fetch (distance), and duration.
Fully developed seas require sufficient fetch and time.
Significant wave height (Hs) = average of highest 1/3 of waves.
Safety Considerations
Expect occasional waves up to 2x significant height.
Crossing seas (wind vs swell) create confused conditions.
Shallow water increases wave steepness and breaking.