Have you ever wondered how does Surfline determines surf heights and quality ratings? If so, you’re in luck, because we dug through the archives to resurface this article from Surfline founder Sean Collins. Here’s what Sean had to say on the subject.
“We used to have long debates about this before we launched Surfline’s 976-SURF in 1985. How do we accurately communicate surf heights and conditions for multiple spots along the coast in a single 60 second long pay-per-call recording to a large audience? Should we rate surf heights by the offshore swell heights, the backs of the breaking waves, or by surf face heights? And obviously what might be “GOOD” surf to one person may be “POOR” to another.
To ensure that our Surfline reporters would be consistently accurate, we wrote a Surf Reporter’s Manual and developed detailed surf report forms that needed to be filled out for each spot. We also agreed on a few fundamental rules.
SURF HEIGHTS ~ Surf size ratings will always rate FACE HEIGHTS. We will also try to use BODY HEIGHTS as an additional scale because something as simple “4 feet” could still mean different things to different people. To some it would be shoulder high, to others 1-foot overhead, and to the Hawaiians more than 8 feet on the face. But if we say the surf is “4-foot faces at about shoulder high”, everyone would truly understand the size of the surf whether they agreed with our terminology or not.
The Surfline Surf Height Scale is below, and also assumes a surfer on a wave would have slightly bent knees.
1′ = ankle-shin high
2′ = knee-thigh high
3′ = waist-belly high
4′ = chest-shoulder high
5′ = head high
6′ = 1 foot overhead
8′ = 3’overhead
10′ = 5′ overhead or Double Overhead faces
12′ = Double Overhead+ faces
15′ = Triple Overhead faces
20′ = It’s just really big
Here is a great FORECASTER BLOG that goes into a more in depth explanation of our surf height rankings.
Advanced surfers may have higher expectations, so what might be rated GOOD by an average surfer might only be rated FAIR by an advanced surfer.
SURF QUALITY ~ Ratings will be a mix from all of the variable conditions contributing to the overall surf quality and surfability of the surf for surfers of average ability. These contributing conditions will include wind and ocean surface smoothness quality; the overall wave shape of most of the waves; how the tide is affecting the surf with bumps, rips, and/or currents; and any other factors that might affect the surfability of the waves. We never want to limit the ratings to only one variable condition – such as a very glassy and clean water surface that might be rated GOOD. But if the waves are 1-foot and crumbly, it’s really POOR for surfing no matter how clean and GOOD the water surface may be.
Advanced surfers may have higher expectations, so what might be rated GOOD by an average surfer might only be rated FAIR by an advanced surfer. And what might be GOOD to an advanced surfer might actually be POOR for a beginning surfer because the surf might be too big for their ability. But as long as a surfer understands the quality of the surf regardless of their ability we will have accomplished our goal.
The Surfline Surf Quality Scale
© Copyright 2000-2010 Surfline/Wavetrak, Inc.
1 = FLAT: Unsurfable or flat conditions. No surf.
2 = VERY POOR: Due to lack of surf, very poor wave shape for surfing, bad surf due to other conditions like wind, tides, or very stormy surf.
3 = POOR: Poor surf with some (30%) FAIR waves to ride.
4 = POOR to FAIR: Generally poor surf many (50%) FAIR waves to ride.
5 = FAIR: Very average surf with most (70%) waves rideable.
6 = FAIR to GOOD: Fair surf with some (30%) GOOD waves.
7 = GOOD: Generally fair surf with many (50%) GOOD waves.
8 = VERY GOOD: Generally good surf with most (70%) GOOD waves.
9 = GOOD to EPIC: Very good surf with many (50%) EPIC waves.
10 = EPIC: Incredible surf with most (70%) waves being EPIC to ride and generally some of the best surf all year.
Surfers don’t usually consider WAVE CONSISTENCY but it’s a huge factor that can often make or break a good surf session. As an example, during an observed surf report most of the waves might be in the 2-3 foot range (knee to waist high) with poor to fair shape, but every 15 minutes or so a set of three head high+ waves might come in with great shape. In that case we might give it a 2-3 and FAIR rating but explain in the description that there are some better inconsistent set waves.
Wave consistency and the your personal wave count may vary greatly depending on the spot and the crowd. For a comparison, let’s say we have 50 surfers in the water during a 4-foot swell with sets that come in every 5 minutes with 3 waves per set (typical for an average Southern Hemisphere swell). That works out to a total of 36 waves per hour from that swell.
At a wide open beach break like Huntington there might be shifting peaks with a spread out crowd so there would be various opportunities to catch waves up and down the beach. But at a point break like Malibu most waves will be rideable all the way down the point, so generally the best surfers will catch most of the waves and have time to paddle back up the point before the next set arrives. If there are 50 people out at Malibu on a swell like this most people won’t get waves to themselves because there simply aren’t enough waves.
A very consistent swell would be the same 4-foot swell with sets every 5 minutes, but now there are 10 waves in every set and that translates into 120 waves per hour. If we have those same 50 surfers out at Malibu there should be enough waves for just about everyone. But it’s more likely on a swell like this there would be 200 surfers and you know the best surfers will still be hogging all the better waves right? Face it, surfers are greedy souls…
Wave consistency is a very difficult variable to forecast and depends on how far away a surf spot is from the storm that generated the swell, the length and width of the storm fetch, the consistency and duration of the wind velocity in the fetch, and how the local bathymetry offshore will refract the swell into local spots. As we learn more about how to track and analyze storms we’ll continue to improve our forecasting of wave consistency.
And who knows? Maybe in 5 years we’ll be able to tell you exactly how many waves there will be during each hour at every spot along the coast so you’ll really know before you go.
In the meantime, hopefully this blog will help you to understand how Surfline rates the surf so you can use us to score more waves.
See ya out there, Sean…”