Swell Period
The swell period can be crucial in determining how big and powerful a specific swell is or going to be. Old Man Surf Report (Old Man’s) gives the user multiple ways to view existing, as well as future swell periods.
First let’s define Swell Period: by definition, swell period or swell interval is the time required for one complete wave length to pass a fixed point, and it is given in seconds.
Longer swell periods mostly in the range from 10-20 second+ intervals are usually the result of an area of low pressure storm or “fetch”, with its wind’s blowing over a large area of water. The larger the disturbance is, the more intense the wind is, and the longer the fetch lasts, generates larger and longer period swells.
Opposite in nature, swells with an interval of 10 seconds or less are usually wind-swells. Usually wind-swells are the result of storms just off the coast, creating wind, and wind-swells with short periods.
This Old Man’s how-to video will show users how to view and interpret swell periods
From the man screen tap on that little circle that is showing 2.5’
The screen changes to a larger circle showing the 2.5’ with a number underneath it “15.5s”. We are seeing at 10am, “15.5s” is the present swell period
Now, Tap on the big circle to go back to the main screen. Look at the green bar graph and view the swell period trends for that day. Swell periods are not moving that much
In the upper right-hand-corner, Tap on the green arrow to go to the next day to view the swell periods. Repeat 1 through 3 (Tapping on the big circle, viewing the swell period and back to the main screen to see trends)
Now, on the main screen, we see it is the next day, 10am, Sunday. From the green bar graph lets view swell period trends from 12am to 9pm. At 12am we see a "14.7s" swell period and at 9pm, the swell period is rising to 18.4s.