In one of my recent posts I talked about my use of Windy.com and how much I like the GUI they have developed. It’s an easy way to look at the two-main worldwide weather forecasting numerical models, the GFS and the ECMWF.
Almost a year ago today, I wrote the post “The Atlantic is a Harsh Mistress”. This was my first reaction to the reality of what we experienced versus the anticipation of what I expected.
I had read so many accounts of boats crossing oceans. Not having any experience, myself I was not sensitive to the subtle differences of the trade wind Pacific versus the Atlantic.
Hey, it’s the trade winds, characterized by strong steady winds and large, 15 to 30-foot-long period waves.
Easy Peasey, as Micah was fond of saying.
I’d just read an account of Kadey Krogen 42 doing the much longer passage from the California to the South Pacific and Australia. Their only problem was boredom and they ran out of Coca Cola. I wouldn’t have those issues. Having lived in Europe on and off for years, I’d long ago learned it best to wean myself off American products. And boredom, not when I had countless hours of Korean Dramas and a crew mate in Micah, who also liked them as much as I.
I still vividly remember leaving Heiro, the western most island in the Canaries to small seas and steady winds. After the first hour, I found myself thinking this could be an easy three weeks. An hour later, as the seas and winds increased, I deployed one paravane stabilizer, another hour later, I deployed the second. We stayed in that configuration for the next three weeks.
It was anything but easy. The passage was characterized by three wave sets (swells).
Swell are longer period waves that develop when the wind blows over the ocean for long period of time. Thus, winds and storms, hundreds or thousands of miles away cause swell.
The primary wave set or swell was from the east, the second from the northeast and the third from the southeast. The third had the longest period (time between waves) of ?15+ seconds. The other two, were on the order of 9 to 12 seconds.
On top of this all, were the wind driven waves. These waves are created by the wind at that location and if the wind stops the waves stop also. These waves had a period of about 7 seconds.
The result of all this was that we had 12 to 15-foot waves from the east, right behind us. My Kadey Krogen loves following seas, but what made it so difficult was the other two swells with different periods hat produced a corkscrew movement. Then every 8 minutes or so, the NE and SE wave troughs would meet under the stern of Dauntless and we would do this wild corkscrew movement with first the bow pointing to heaven and then seconds later, twisting down.
It was a wonderful corkscrew if I was on a roller coaster.
Here are some videos of the experience:
I love my boat so much.
So that was my introduction to multiple swells. Oh, I had noticed it before in the north Atlantic, but I attributed to “rogue” waves and it was not so systematic as in the trade winds.
The result was best described by some sailors I met in Martinique who had just done the same crossing. They called it the bathtub, because the water was so disorganized.
Getting back to Windy.com, if you open the page, https://www.windy.com/21.576/-45.264/waves?waves,19.746,-41.594,5
On the far right, you can see the vertical column where “waves, swell, swell2 and swell3” can be chosen.
Looking at this data today, mid-March, it’s also apparent why the best time to cross this part of the Atlantic is in early winter, as the when we crossed in December, at least all the winds and waves had an easterly component. Now, you can see that there is a swell from the northwest, that must be very unpleasant.