As a boater, you are probably familiar with buoy data available for your area, These floating buoys and land based weather stations report on a variety of data points that are useful for understanding the conditions that are present or developing as you plan your voyage. A great place to start is the National Data Buoy Center (https://www.ndbc.noaa.gov/) which shows a map of all the available stations and buoys. So what does it all mean and how do you best make use of the data available?
Data Layout
The layout of the data follows a consistent format and field definition. Depending on your source for buoy data, the presentation may vary. The following is the data as presented on the NOAA Data Buoy Center.
You may notice that depending on the type of buoy and its current operational condition, data elements will be different. For example, most floating offshore buoys do not have wind data and only report wave information. And, even stations that have wind sensors, may not be functioning correctly and not reporting data.
Wave Height (WVHT)
This is generally the single most important data point for boaters. Wave Height describes the height of a wave from the trough to the crest and reported in the US in feet. To view the data in a meaningful way, focus on the historical data to understand the conditions that have prevailed over the last few hours. It is important to understand the wave data and its relation to the wind. Locate another station with wind data, and correlate the wind conditions with the observed wave data.
Wave Period (DPD and APD)
Wave Height alone only tells part of the story without understanding the Wave Period. The Wave Period describes the distance between the crest of successive waves. It is reported in seconds and is shown as the Dominant Wave Period (DPD) and Average Wave Period (APD). The Dominant Period will highlight the most energetic waves and are a better data point to use.
Mean Wave Direction (MWD)
Mean Wave Direction simply describes the direction the waves are moving.
Now you have four basic data points that tell a story. You know the height, which depending on your vessel and experience, may be enough for you. But the wave period will tell you a lot about how your boat will behave and what a voyage will feel like. A period of 3-6 seconds, will describe choppy seas. A period greater than 6, will translate into a moderation of wave height as the main consideration and will describe a swell condition. The wind will help you understand if the wave data is driven by regional wind conditions or if offshore winds are driving swells. Here is where your awareness of the prevailing conditions and your boat's handling characteristics will be critical.
Make a Prediction/Decision
Let's apply the data displayed above to a 28 foot center console. With a wave height of 3.3 feet, our first take is that it's a bit much for a comfortable day out, but let's look at the period. The wave period looks like 4 seconds. That is pretty choppy, and at that wave height, a no go.
But how about later in the day, or maybe tomorrow? Checking on another buoy that has wind information, I see the wind is 16 kts with 20 kts gusts. I check the Zone Forecast and I see that the wind conditions are expected to continue for the next 48 hours at the approximately the same speed and direction. Time to go work on your golf game!
Get Your Data
Although the NOAA site has tons of useful information and capabilities to further drill down, it doesn't represent a very usable mobile experience. Check out our article Killer Apps for Your Boat that reviews the Buoycast app.