Hawaiian scale

Hawaiian scale is an expression of the height of a wind wave affecting water.It is the expression conventionally used by surfers in Hawaii and is also used[clarification needed] in Australia and parts of South Africa.Commentator Neal Miyake has proposed the following candidates:[1] In Australia, which otherwise uses the metric system, surfers and surfer-oriented media such as Australia's Surfing Life and Tracks magazines still measure and describe waves in terms of feet.Some journalists and media outlets that provide information to surfers but are not staffed by insiders to the sport express wave size in metric units using direct conversion from a literal interpretation of the scale's output,[2] e.g., labeling as "1-metre" a wave that insiders would describe as "3-foot" or slightly larger.This heuristic finds mathematical support as a compromise between two methods of expressing the combined effects of a wave's average upward and average downward deviations from mean sea level, namely a) the sum of the absolute value of a sine wave's average (mean) deviation during its upward half-cycle and the absolute value of that mean deviation during its downward half-cycle (|0.637| + |-0.637| ≈ 1.273)[5] and b) the sum of the root mean square (RMS) amplitude of each of those half-cycles, i.e., twice the RMS amplitude of either half-cycle (2[0.707] ≈ 1.4014), each of which expressions is within between 0.06 and 0.07, or within between 4.5% and 5.25%, of the value 1.3 yielded by the heuristic for that sine wave when 2⁄3 is multiplied by the sine wave's crest-to-trough (peak-to-peak) amplitude of 2.
Figure showing the scientific standard of measuring wave height (from trough to crest). The Hawaiian scale would instead measure from calm sea level to crest, reporting half the height.
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