How big is a 6 foot wave?
We recently had a solid pulse of waves in the UK. Proper ground swell with light off shore winds. Just at the upper limit for the beaches before they are unmanageable.
I was on my way to Croyde, my local beach break. Magicseaweed was predicting 5 - 6 ft at 17 seconds. Fully aware that this can mean anything from chest high to double overhead faces, I had a board that I was testing in my car. A hybrid which is good for most UK conditions.
I saw someone that I know on my way to the beach. He had just been surfing. I asked how big it was. “Solid 8 foot” was the reply. I don’t know this person well enough to identify which method he was using. Did they mean 8 ft faces, or 8 ft ‘Hawaiian’ which could potentially be massive? I didn’t have time to stop and chat. I carried on to the beach wondering if I would be under gunned on my daily driver.
I arrived at the beach. I didn’t stop to wait for sets, but it looked solid. I hadn’t ridden the board that I was testing – a 6’4 Matta 2825 in any decent size waves, so thought that this would be the perfect opportunity. I excitedly yanked on my wetsuit.
Scott (author) at Devon reef. 6 foot Hawaiian?
There was a strong rip running North across the beach toward the rocks. Just before I paddled out two people had been plucked off of the rocks by the coastguard. I elected to paddle out on the South side of the beach. It was a tough paddle against the rip while trying to penetrate the sizeable swell. By the time I had made it out back I was close to the rocks. I paddled across to the other side of the beach, as this was picking up most of the swell and had occasional nicely shaped sets.
I was talking to a friend between sets. We were discussing how quiet it was. He said that a lot of people had gone to more sheltered spots. He wondered why no one would want to surf “perfect 4 - 5 ft Croyde.” I had a little laugh to myself, thinking that only 20 minutes ago someone else had told me that it was 8 ft and Magicseaweed had predicted 6 ft.
I got a few waves during that session, but felt totally under gunned, I struggled to paddle into the sets. Most of the good waves were had by people on bigger boards.
With the right conditions Woolacombe can handle some size.
The following morning, I got up before light expecting to surf a local reef / point break. I was checking it with a local charger. It looked too big for the spot that we were checking, so we elected to try Woolacombe – a nearby beach that can handle decent size swell at low tide. This time I had my 6’10 step up. The waves were big. We paddled out and there were only four of us in the water for most of the session. I was glad to have my 6’10, I caught some screamers.
I saw someone I knew when I got out. We were chatting about the swell. I told him that I had surfed Down End – Croyde the previous day during the peak of the swell. “What?” he replied, “I was watching, it was triple overhead!”
So, I have had four completely different measurements for Croyde that day, ranging from 4 - 5 ft to triple overhead. For a beginner surfer, it must be a nightmare to decipher how surfers measure waves. I have over 30 years’ experience surfing and I still get confused about how it’s done.
An illustration of the amplitude of a wave. In our example the horizontal line represents sea level.
The source of this problem is the two opposing methods that surfers use to measure waves. The Hawaiian method measures a wave in the same way that a wave size is determined in Science. The amplitude of a wave is the measure of a wave from its resting position to the peak of the wave. So, in our case the horizontal line in the diagram is sea level. This is the resting point. As an observer of a wave in the sea we could measure the amplitude by viewing the wave from behind. Or as an observer from the shore you could half the size of the wave face. So, we could say that a wave with a 6 ft face would be 3ft using the Hawaiian scale.
In 1964 Willard Bascom introduced an opposing method. This required the observer to assigning a wave height based on the size of the wave face (from the front). As with the Hawaiian method, this can be most effectively measured if there is a surfer riding the wave.
This can get confusing when you ask someone for a surf report:
ME: “How big are the waves today?”
FRIEND: “Solid 6 foot”
ME: “OK……….. about head high then?”
FRIEND: “No 6 foot” (indicates by pointing with an outstretched arm)
ME: “Oh. 6 foot Hawaiian”
Hawaii's crown jewel. How would you measure this wave?
Depending on which continent you are on wave height can also be measured in either imperial or metric units (feet or metres). And to complicate things even further, some people measure the height of a wave using the human body as a scale. To do this you measure how tall a wave is in comparison to an average size person. ‘Shoulder high’ or ‘double overhead’ for example.
As if this isn’t enough, there is another factor to consider when attempting to ascertain the size of a wave. Bravado. If someone tells you that the waves are “6 ft Hawaiian” you would assume that the wave would have an amplitude of 6 ft and therefore a wave face of 12 ft (or double overhead). This is almost always not the case. Normally the size of a wave will be played down by the person reporting it. So, what someone reports as a 6 ft Hawaiian wave could potentially be much bigger than you would be led to believe. And the opposite can happen when you are asking someone that is learning to surf. A beginners perception of wave size can often be inflated.
Nazare has been measured at 100 foot (wave face)
To add a final layer of confusion, when waves reach a certain size, they are only measured from the front (using the Bascom method). To my knowledge there is no official point at which you start to measure a big wave from the front, but it is generally around 15 – 20 ft Hawaiian, which could mean anything. If you ever hear big wave surfers talking about the size of the wave at Mavericks or Jaws for example, they are always measuring form the front. Why?
I was watching a YouTube vlog the other day when a Hawaiian surfer referred to Pipeline as solid 6 to 8 ft (Hawaiian) and then compared it to the conditions at Jaws, which he said was 30 ft (faces).
For years now, I have only measured waves using the human body as a reference. “It’s head high.” or “Its approaching double overhead today”. You know what I’m talking about straight away. There is no confusion. Give it a try. Just think how much time would be saved trying to work out the size of the bloody surf!