On a seemingly calm morning with little wind and nearly no waves why would we still be having a rocky ride? Swells – three to four foot sea swells! What are swells and why would there be any on a calm day? Those were my questions.
Doing some research and asking Luke – who knows about these things, swells aren’t necessarily caused by immediate wind such as waves, they typically occur when there are storms at sea and are the result of wind transferring its energy to water. According to Sciencing: “A swell in the ocean is formed through a combination of wind strength, wind duration and fetch. Wind strength is how fast the wind blows across the surface of the ocean. Wind duration is how long it blows without interruption. And fetch is the distance wind blows across the surface without disruption from obstacles. As wind blows across the water’s surface friction occurs and energy is transferred from wind to water. The result is a rising crest that forms into a wave. Over time and distance, sustained wind strength and duration build up a large amount of energy beneath the ocean’s surface, forming deeper waves known as swells. This energy fuels a swell so it can travel thousands of miles without changes in height or shape.”
Swells have characteristics of height, period or frequency and direction. The height is measured from the bottom or lowest portion to the top or peak of the swell. Since these waves have been traveling quite a distance their tops are rounded and heights vary. When a forecast calls out swell heights or as I did at the beginning of this blog, it is usually done as an average. The period is the time between swells. The more frequent the time between swells, the more bumpy the ride. However, high swells farther apart can also create a very rough ride. The swell’s direction is where it is coming from. The ocean floor affects the direction of the swell’s travel and its speed. Swells in deeper waters will maintain their speed but, shallower waters will cause the swell to slow down and “bend” altering its direction.
This morning as we were underway we were apparently experiencing the effects of a storm perhaps hundreds of miles away. It is interesting to think about something you can’t see or have no known knowledge of affecting your wellbeing on such a physical scale. When we started our cruising travel adventures I thought we had things on the boat pretty well secured in that sea movement is a given but, never having done anything like this I didn’t know what to expect. A couple of weeks into our trip, one morning as we left the confines of a harbor we encountered rough weather AND our stabilizers broke. As we had just gotten underway and I hadn’t been expecting this double whammy I rushed around – as best one can when rocking and rolling and pitching and yawing, to shut cabinets, close portholes and make sure that anything that could fall or fly was stashed away. The dogs don’t like it when it gets rough and they become velcroed to me. It’s best if I can just sit on the couch and they can hunker in my lap or next to me but, when I’m moving they are underfoot. All of a sudden the bow hit a big swell and things started flying. I couldn’t get a footing because the dogs were under me, I tried to grab onto the counter to brace myself but, to no avail and went down! The fridge made its way out of its secures and the stove took a walk into the middle of the galley! Thankfully, no one got hurt and nothing got damaged. While it provided a healthy scare it proved to be a “good” experience. From it we learned what we needed to secured better and what needs to be tucked away while underway. I now have a mental checklist of the steps to take to “batten down the hatches.” That said, each time we encounter swells, while I think we may be prepared there are usually slightly different movements and new disruptions. Each trip has its own learning curve.
I’m beginning to realize how so much of boating is a metaphor for life itself. In this case, there are lots of ups and downs and sometime you’re prepared for them and other times not so much!
2 thoughts on “Swells”
Loved coming along for a ride in the video! And love your sailing/life metaphor! And thanks for a science lesson. The transfer of energy from wind to water makes perfect sense.
Such interesting stuff! Or better stated, information. Very much enjoyed the knowledge.
When we crossed Cape Cod bay with you, Luke was a wealth of knowledge.