What does a sea scale measure?

Answer by  LeheckaG (1826)

"Sea scale" is typically Englishman H.P.Douglas's 0 to 9, two-code, "sea scale"; which is used to assess the state of the sea for navigational purposes: the character & height of the waves, and the swell of the sea. 0 = calm, no-swell; ... 9 = 14+ meters/phenomenal, confused/indefinable-wave-heights/lengths

Answer by  Russty (166)

The Douglas sea scale measures the height of waves and also the swell of the sea. It was created by H P Douglas in 1917 to help estimate the roughness of the sea for navigation. The scale has two codes, the first for the state of the sea, the second for describing the swell of the sea.