Spencer Rogers is a coastal specialist with N.C. Sea Grant and co-author of “The Dune Book.” Here he explains the basics of ocean waves. Questions and answers have been edited.
When these different waves pass a point at the same time, they simply add to or subtract from each other. When the crest (top) of wave meets the trough (bottom) you get a smaller wave. When the crests meet, you add the two heights and get a much bigger wave.
On any given beach, most of the waves arrive from similar sources depending on the season, so the common sets might arrive every third wave. On another beach it might be every seventh, or somewhere in between.
Want to catch the biggest wave? Watch the waves from shore. Count the number of breaking waves between the biggest waves that you see. Use that number to pick the biggest one to catch once you get in the water.