How to measure wave height

Interesting discussion on estimating breaking wave height on another website. Seems we fall into 3 camps.
-Back of wave and call it low.
-Tries to be mm perfect trough to crest at front
-The 'bulls*#^!' always when your at work or not looking, usually about double actual size.
Anyway I guess it's a matter of perspective. Waves seem smaller to me kiting or surfing, than when I'm out fishing in a boat, or trying to cross a bar. I can only guess laying on your guts on a booger in the trough of a decent wave would make it feel much larger. Has kiting got a set standard anywhere, or do we follow surfing and mix it up?
I'm used to calling it somewhere between back of wave and face. I don't know why. It's just what I grew up with. Any way after reading the following article, I may have to change.


This piece was interesting on the history.
Ricky Grigg, in HOW TO MEASURE A WAVE, printed in the Surfers Journal volume 12, number 1, 2003 wrote:
"Once upon a time, an old Hawaiian surfer told me that those surfers who measure from the back have already missed the wave. Of course, you could argue that surfers who measure the wave from the back do so on purpose so that they can purposefully underestimate their size. But why would anyone want to do that you ask? Perhaps they are the macho guys. "Shucks ma, that overhead wave is only three feet, at least to me. Its no big deal". But then one day a wise guy like me comes along and says, "Three feet, for an overhead wave? What are you anyway, only three feet tall?" The 5'6" surfer says, "Huh? What? Are you blind?" "No" I say," maybe you are blind. That overhead wave was way over your fully upright body." "Hey man," he tells me, "you measure waves from the back." I say, "You mean the back of the wave you can't see?" And of course he says, "Right on, dude, right on"

Wish that all this banter was much ado about nothing, but unfortunately it is not. There is a history and a very good reason why so many surfers these days measure from the back. Let's go back about 40 or 50 years in Hawaii and revisit the golden years of surfing and try and find the answer. Back then waves were bigger, bluer, and much less crowded. Surfers at Waikiki rode huge waves all measured from the front. Duke Kahanamoku's famous 1.1mile ride had to have been 20"plus when it first broke at first break (out near Castles). Today's surfers would have called it 10' had they been there. Trouble is, had they been there, they would not have been able to see the wave, at least not from the beach. So how did all this back of the wave nonsense get started anyway?

I was surfing the North Shore in those days, the late 50's, 60's and 70's, and what started to happen very slowly over this time period was a gradual tendency to underestimate waves. As it got worse and worse, everyone started realizing that the smaller the estimates were, the smaller the reports were on the radio and TV, and fewer and fewer people were showing up to surf on any given day. Hey, man, this was way cool. A super cool method began to develop to keep the surf a secret. Eight to 10' waves at Sunset slowly became 4-5' with a few pulses. But how in God's name could anyone call an 8' wave 4', or a 10' wave 5'? Not that difficult. The surfers and lifeguards simply invented an new system of measuring the waves from the back. It worked great, because, of course, waves from the back are about half their size from the front. Since few people could actually see the backs of the waves, few people could disagree or claim otherwise. Fewer Townies went to the North Shore and the local guys had the waves all to themselves. The lifeguards liked it too, because they had fewer people to guard and so they could go surfing longer. The system prospered and more and more surfers grew up believing that measuring the waves from the back was the way to do it.
End of story.

There were a few old-timers around who remembered the old way, the first way, the simple way, the face-value, from-the-top-to-the-bottom way, from the front, from the crest-to-the-trough, the way oceanographers define wave height, the way in which ordinary people can judge a wave simply by looking at it. By its face value. Not only did the old-timers remember, but they also reminded the lifeguards about safety. It wasn't to safe to broadcast to Hawaii's tourists that 8-10' waves were only 4-5'. People drowning and getting slammed into the bottom by shorebreak could sue, and guess what, they did sue. A number of visitors throughout the Islands suffered severe neck injuries producing paraplegia and quadriplegia, all caused by shorebreak waves that were larger than those reported. Several cases were settled or won to the tune of millions of dollars. It was not long before the City and County of Honolulu was under a powerful economic and legal gun to change the system back to the old way of measuring waves from the front by the face. This old way is now called the "new" way, because so many young surfers never heard of the old way, until now perhaps.

The "new" has been adopted by the National Weather Service in Honolulu and is now reported by all of Hawaii's news media: newspapers, radio, TV - everyone. Even the lifeguards are now reporting face values. A special course in how to measure and report surf was designed by the National Weather Service tailored specifically for the lifeguards of the City and County of Honolulu. Over the course of about 15 months (in 2000 and 2001) about 80 lifeguards successfully completed the class. With this new awareness, the lifeguards have embraced the "new" policy. And, there is no question that their first and foremost concern is safety for Hawaii's visitors and residents alike. Its been a rapid transition back to the old way, the simple way, the safe way, and the HONEST way. Its just like my old Hawaiian friend said, "Never measure the wave you missed. It's the one you ride that counts"

tape measure

how do you measure a wave from behind that is dredging below sea level?
waterproof calculator

cant measure chopes from the back eh?

By sight

Yeah, who would have thought it - Waveslave is actually Ricky Grigg

I agree. Unless your at your local; it's hard to estimate from shore. I've been trashed surfing unfamiliar breaks that looked way smaller than they surfed. Looking over flat water, from high above, or when the break is a long way out can make it more difficult. Film (esp surf cams) don't do wave size justice either. I guess my interest stems from the fact I did beach and surf reports on the radio years ago, and was calling it incorrectly the whole time. When marine reports were calling 4m swell, I was only calling 6-8 foot. Luckily it was before the 'sue for damages' mentality set in in Australia. The internet broadcasting seas, swell size, direction, period, and synoptics give us more accuracy then we have ever had. In conversation I don't think I even call a height anymore. Knee high, Head high, Stand up; thats about covers everything on the east coast

Funny this should come up. I was having the same conversation with my Wife when we were watching Bells last weekend. A grommet was interviewed and was asked on the the size of the waves. Straight away he said, 2-3 foot, on overhead waves. The commentators were calling 5-6ft. I never could understand calling it from the back. I am glad the Hawaiians have finally woken up.

There is only three sizes. Too small, Big enough, And too big.

yeah same Pearl...did a surf report for almost 20 years on local radio...got sick of the macho's telling me I got it wrong, so I came up with the small,medium,large concept.

Very interesting post from Pearl.

This is something Ive often asked myself, when standing watching the wave break asking somebodys opninion on the size, they reply "3-4 feet" when clearly theyre breaking a good foot higher than a 6 foot person. Work that one out ?

Spot on

I usually find out just a moment to late when a wave is toooooo big, followed by a swim back to the beach ( or a tow from Lloyd )

On the same day, different beaches break different sizes.
How ever many foot over head is conceivable for most.
Most people are similar heights - 5 to 6 foot tall.
It wouldn't be any good for Laurie cause he is very tall.

No Col. That's a quote from Ricky Grigg talking about the Hawaiin history. I do have the hairstyle of 65 year old though.

On a hydraulics course I did years ago, the then theory was that you measure the wave face and multiply it by a factor related to the slope of the sea-bed below it. E.g., a flat beach with a slope of 1:500 would have a factor of say 0.7, and a reef a factor of 0.4, so a 10 foot face on a flat beach, would have a swell size of 10x.8 = 8 foot, yet a 10 foot face on a reef break would be a swell size of 10x0.4= 4 foot.
Can't remember how they went about calibrating the floor factor though as it was a long long time ago.

If it takes three weeks for two men to walk a fortnight, how far would they get in a week.