Enter calm seas as 00. Enter 99 if a period is confused. Enter the height of the significant wind waves in feet. 2.9.5 Columns F and G - Swell Waves, Direction, Period and Height . Enter the hundreds and tens of degrees of the direction and average period of the swell waves in seconds from which the primary swell is coming from in Column F .
Secondary swell is entered in Column G .
Enter the period as described in paragraph 2.9.4. Enter the average height of the swell waves in feet. Fully arisen Fetch Area Duration Wave Period in Seconds Speed wave height minimum in minimum knots in feet naut.