The surf was up this past Sunday, with big swells coming ashore and producing some nice surf-able waves along the Massachusetts coastline. These were the result of a weather system offshore that had moved out and left the residual swells behind. Before heading out on the boat, I checked the data from the 44013 weather buoy (pictured above) on wunderground.com, and it was reading 4-5 foot wave heights. However, the buoy was also showing a spectral period of over 11 seconds. The latter statistic is an important consideration as swells with an 11 second period are so far apart that one can coast up and down them very smoothly. A 4-5 foot sea with an 11 second wave interval makes for much more pleasant boating than a 2-3 foot sea with a 3 second interval. I think we can make a rule of thumb out of this…a wave interval of less than 1.5X the wave height will be uncomfortable, >1.5X is pretty comfortable…..but don’t hold me too this. As one can see from this video, I cruised up and down these big swells like they weren’t even there. These are solid 5+ footers, but you have to look hard to even see them.
I remember once fishing off the coast of Hawaii in water that seemed extremely calm. When the captain told me that the waves where 10-15 feet, I did not believe it until I saw the shoreline disappear and re-appear as we were lifted up and down by the huge swells. It turns out that the interval was over a minute, so the waves were barely visible.