How To Read The Buoys

| posted on July 25, 2011

Its not black magic or palm reading, but rather it's understanding the buoys that keeps Ian Walsh in the right place at the right time. Photo: Aeder

Although most of us would never admit to it, there are tens of thousands of surfers that understand buoy readings about as well as we understood Inception. Unfortunately, there’s a whole mess of good intel the buoys are offering that’s falling on deaf ears. To set us wise on just what the buoys can tell us, we called on Ian Walsh, a man so in tune with the inner workings of forecasting that he doesn’t even bother to read buoys anymore; buoys read him.

General Forecast Vs. Buoy Readings

“A general forecast can help you get a picture of what a swell could produce while an actual buoy reading confirms just how big or small the swell really is. The numbers coming off of a buoy are a pure reading of what the ocean is doing at a certain point in time. It really is a much more accurate depiction of the size, angle, and winds of an oncoming swell. A general forecast, on the other hand, is just a prediction of what the swell might end up doing.”

The Period

“When you start reading the buoys, you’ll hear the term ‘period’ used a lot. The period of a swell refers to the time between each wave in a set and has a ton to do with the size, speed, and the overall condition of a swell. If a buoy reading says ‘10 feet at 20 seconds,’ that means it took 20 seconds to pass between the top of first wave (which was 10 feet) in the set and the top of the second wave in the set.”

Long-Period Vs. Short-Period Swell

“If you’re tracking a big storm out in the ocean that’s sending swell to a surf spot far removed from the storm, you’re looking at a long-period swell. These types of swells are a lot cleaner and more organized because the swell has had a bunch of time to clean up as it heads through the ocean.

“If that same storm was much closer to the shore, then it would give off a shorter period read on the buoys because it’s had less time to get to the lineup. As an example: a reading of 10 feet at 20 seconds would be considered a long-period swell while a reading of 10 feet at 12 seconds would be a short-period swell. Again, a longer-period swell will be cleaner while a shorter-period swell will be a bit more mixed up and look like storm surf.”

Dialing Your Buoys

“Once you start to pay attention to the buoy readings, you’ll begin making associations with readings on days that were really good at certain spots. If we see a swell forecast for Jaws that’s supposed to be really big, I’ll check the buoys as the swell starts to finally hit Hawaii. If it’s above a certain size and period, then I know it could be on and I’ll start checking the angle of the swell to make sure it’ll hit the reefs right. Every wave likes a different size, angle, and swell direction, you just need to do the research to figure out the right readings. Once you get that dialed, that opens up a lot of doors and you’ll probably be getting barreled a lot more.”

  • Birds Surf Shed

    Thanks for the article. Dial in the buoys and you’ll always no where to surf.

  • Buoy Alarm

    Although forecast models keep getting better, nothing beats the real-time reports from ocean buoys. Models are generated by computers, while buoy reports are actual, observed data. Use forecast models to predict what might happen, use buoy reports to know what _is_ happening.

  • Robert Fischer

    Good article. I have a friend that is a local zen master with surfing and the weather. I am a 43 year old rookie but love being in the water and learning. I am still in the “Surf what you have today” mode rather than chasing the swells around the area. I guess that comes with time.

    Thanks for the information and incredible pictures.

  • Miguel

    Great article. All the numbers and arrows on magic seaweed finally make sense.

  • nearly

    Ian, period is power, nothing to do with surface wave quality unless you’re looking at everything running at the same time. Also it’s not the time between the first and second wave in a set, it is an average of the top third of the waves. Same as height, that’s an average of the top third too. With any swell there will be waves up to twice the size of the third highest average. Say when a forecaster calls 3-6ft it mean that is the range in ocean swell size.

    For example a buoy could and often will tell you the swell is 10ft at 20 seconds headed towards your reef. The real picture is often more complicated with say for example a 6ft at 20 second swell headed one way and 10ft at 12 secs headed in another direction. The buoy reads the dominant features and tells you it’s 10ft at 20 secs coming at ya. Why? Because it is a computer just like a model, it can only tell you what it has been told to tell you or is able to measure. All the while it is still an average, an average partition the buoy has been programmed to mathematically decide upon.

    That accounts for most buoys. However buoys also come in many shapes and flavors, those that return the full spectral output are incredibly useful (but if you don’t understanding forecasting it’ll be useless as it’s exactly the same info) and those who don’t provide a full breakdown are just producing a very generalized picture, often one that’s misleading.

    Upshot is: learn to read a full spectral forecast/buoy output. The ocean is a myriad and complex beast which you have to learn to read properly eventually.

  • Judge #3

    Hey Nearly….

    No one cares

  • Nearly

    Hey Judge, why are you reading an article on buoys then? Go shuffle one off on the Fish’s latest chest wax vid, more your level.

    Turns out Ian doesn’t know his stuff, same as most bro pros. Shame that Surfer obviously don’t know their stuff either which is why they are being battered by Surfline/Coastalwatch/Magicseaweed who are actually about surfing. It’s about the swell, the waves you catch and that means you must be able to read a chart properly.

    Or you could just whack off in your condo with the curtains closed and hope there’s a wave when you hit the beach.

  • Hayden

    Always good to know the period when heading off to catch clean waves. Thanks for the reminder.

  • DAMIAN66

    I have to admit, watching Inception was like exiting but when my girlfriend asked me about a certain scene, I ducked the question with the good ol’ , “want ice cream?” thanks 4 the info guys, been everywhere in the Americas surfing but I have to admit a few times I’ve missed it and had to do some sight seeing instead

  • Lgreanz

    if you want to be dialed in you need to watch the bouys alot.
    prediciting surf will be easy , but the formula is never 100 %
    and all swells have diferent characteristics from the storms that birthed them.
    and just when you think you’ve got it dialed in and new swell episode will fool you. no 2 swells are alike and the surf wont always be perfect.
    in hawaii a

    10 – 13 sec = got waves.
    14-17 sec per = waves gonna be good.
    17 -20 sec per = gonna be pumping , pack your guns.
    20 + sec period = WTF OMG where should i go hide or I need a bigger board.

    and certain periods mean the storms are weird,(11/12 , 15,19) ideally i think the best swells are the ones with the 13,14,17,20 second peeriods. yet ive seen great days @ (16/18) not sure of an explanation to this just from watching bouys over 10 years. i think alot deepends on the source of the storm and how far the swells have traveled till intersecting with our bouy data collectiing systems.

    studying physics and bathymetry helps too.

  • The KING

    Question! If the buoy forcast says ESE 2 feet at 7 sec, does that mean that the waves are coming from the east / southeast or traveling to the east / southeast? Thanks folks!