Using Wave Buoys

Using Wave Buoys (Cape Elizabeth in this case)

Wave buoys are the best chance we have to know what is really happening out at sea right now. On the beach surf reports are fantastic, but conditions change fast and sometimes a little more information is needed. A decent swell can arrive quickly and the 1ft slop you see when you arrive on the beach in the morning might have been 4-5ft and pumping by late afternoon, if only you'd hung around to see.

Wave buoys are minature weather stations fixed at certain places in the ocean that report, via a satellite link, information about the current conditions to weather monitoring stations around the world. A typical wave buoy will report wave height, period, wind speed and direction and the water and air temperatures. Here is a BRIEF description of what these mean to the surfer:

Wave Height: Not as obvious as it sounds. This isn't the same thing as wave size at the beach. Many factors, including the tide, shape of the beach (sea bed), angle of the swell and more complicated factors like refraction can alter the actual size of the breaking wave. Its up to you to get an idea of what a given swell is likely to do on your favorite beach. However its pretty clear - even to the novice that 15ft of swell is going to equal BIG waves, and 1ft of swell is unlikely to be worth the effort.

Wave Period: This is the distance between peaks in a swell. Doesn't mean much? Think of this as an indication of wave speed and quality. The longer the period the more energy the swell has, the faster the waves travel and the more of a punch they pack. A local onshore wind will produce waves, sometimes even large waves, but with a period of 6-9secs they will be close together, confused, lumpy, lacking in real power. At the other end of the scale swells with a period of over 15 seconds can travel enormous distances and arrive as well defined lines producing ridable, powerful waves. To give you an idea a 3ft swell with a 22second period travels almost three times faster than a 3ft swell with an 8second period!

Wind Strength and Direction: Much easier to understand. Ideally all swells would arrive on our shores from thousands of miles away completely unaffected by local wind. If a decent swell is showing look for light winds, preferably offshore. Strong onshore winds will generate messy, short period swells, and destroy decent swell.

Problems? If you use the buoy data regularly you will notice a couple of problems: Occasionally abberant data gets through - 100mp winds/ 50ft swells etc. Normally this is only a blip and you should be able to check the graphs and spot it for what it is. The other problem is updates. We pull the data every few minutes but sometimes it's out of date at source. We try to alert you of this whenever possible (grey arrows on the wind map mean out of date data) but you should check the times carefully.

Remember what ever happens at your local buoy will have an effect on your local break a while later. This delay will depend on the speed (see Wave period above) of the swell, which can travel anywhere from 10 - 40 miles an hour and the distance to the buoy. This delay allows you the chance of a useful glimpse into the future!