What does the wave composition graph mean?

The buoy composition graph shows you the relative composition of ground swell, wind swell and chop. It's based on a multi frequency energy analysis of the surf about 4 miles west of San Francisco. It also factors in real time wind speeds measured at the coast.

The 0-10 score, shown here with a value of 1.8, indicates the quality of the swell. 0=horrible and 10=beyond epic.

The graph and the score update at least every 15 minutes.

Periods are interpreted as follows

• Below 8s is Chop
• 8s - 12s is Wind Swell
• 12s - 18s is Ground Swell
• Above 18s is Mega Ground Swell

Although we try to make these graphs as accurate as possible, please don't rely on them for anything that might involve injury or death. That would be stupid.