Hawaiian Scale

by Larry Goddard

I’ve been spreading the good word this last week, that…Guess what! The so-called “Local Scale” or “Hawaiian Scale” is just the old way that observers reported surf heights to the old U.S. Weather Bureau (which became the National Weather Service in 1967 or 1970?), only the estimated wave heights in feet were converted to, and were reported in “Half-Meters”, not feet!

The estimated heights did not, and NEVER did, refer to the back-side of waves (a pretty ridiculous assertion, when you think about it! You can’t ride the back side of a wave, nor can you even see it from a position on the beach!) That idea was probably an attempt to reconcile or rationalize the obvious discrepency between what waves LOOK like and what the guys using Hawaiian Scale reported when they mistakenly said “feet” instead of the correct “half-meters”.

So, if you were an observer for the NWS 30-40 years ago, you would estimate the wave heights (from the Kilauea Lighthouse, for example) in feet, then convert that to meters by multiplying by 0.3048, then double that value to get the wave height in the requested units that the NWS wanted…i.e., “Half-Meters”.

So, we have: Height, in half-meters = 0.6096 times Height, in feet

So…5 ft is about 3 half-meters; 8 ft is about 5 half-meters; 10 ft is about 6 half-meters.

Simple, huh? We were all observing and reporting the same waves, just using different units. No more confusion or controversy is warranted if everybody understands the origin of the “Hawaiian Scale”…it’s the same waves that we were all observing and reporting, just using different units of linear measure. You could report wave heights in cubits, millimeters, or “hands”, or body heights. As long as the recipients of the reports know what units you are using, there is no problem.