As a passionate retired science teacher, the Gulf Stream is one of the natural wonders of the world. Basically it is like a giant river of warm water in the sea, averaging about 60 miles wide and 2500-4000 feet deep. Off the east coast of Florida it flows north at between 2.5 and 4 nautical miles per hour (kts),carrying over a billion cubic feet per second of water. (By contrast, the Mississippi river flows at about 600,000 cfs.)
The Gulf Stream is a part of earth’s climate circulation pattern which pumps excess heat from the sun beating down on the tropics, north to the poles and thus it has far reaching effects. For example, even though merry old London is about as far north as Hudson Bay, Canada, it has a much warmer and rainier year round climate, courtesy of the Gulf Stream. Because the Gulf Stream is powered by the temperature differential between the tropics and the northern latitudes, the impact of climate change, essentially a slowing down of the Gulf Stream is already beginning to be measured.
Managing the current’s push
The Gulf Stream presents a unique set of challenges as we plan our voyage from Florida to the Bahamas. First, the current will push your boat north at 2-4 kts as you try to head east at about 7 kts. It’s like swimming across a fast moving river and anticipate the current’s push. You have to account for a lot of drift, so you steer your boat against the current at angles which can be as much as 45 degrees depending on the speed of the Gulf Stream. This, of course slows you down and exposes you to the current for a longer period of time. Yeah, it gets pretty complicated, but fortunately we’re fully equipped with a GPS and electronic chart plotter which we use to calculate and maintain the best course for where we’re heading. We’ll also start as far south as we can before crossing, so we can minimize the current compensation we have to use when we cross.
Waiting for a weather window
The second important consideration is the wind. A wind from the north, pushes against the current creating large, steep and potentially dangerous wave conditions, and we avoid that at all costs. The prevailing winds in Florida are from the E/SE, which is right on your nose if you’re trying to head to the Bahamas. Cold fronts bring north winds once they arrive, but they also relax the prevailing trade winds before they arrive, and after they pull back north. Ironically, the winds will move south and even west with an approaching cold front. So, the trick is to time your crossing either immediately before a cold front, or after one has moved out, before the easterly trades build back in behind it. We have literally waited weeks to get a decent weather window allowing us to cross.
It’s go time
No wait this time! We had our eye on a possible weather window and timed our arrival in Ft Lauderdale on Wednesday, 2/13 anticipating a departure on Friday, 2/15. This window was an “after the front” variety, decreasing NE winds and flattening seas, and several days predicted before the trades set back in. We decided to make the most of it, and sail a full 24 hours from Ft Lauderdale all the way across the Bahama Bank to Nassau. It worked out beautifully. We had very little wind, but as we hit the Gulf Stream (the water temperature rises by about 4 degrees, over the course of several minutes) we encountered what was left of the steep seas, maybe 4-6 feet, uncomfortable, but not dangerous. Within a few hours, the seas had calmed allowing for a delightful sail all the way to Nassau.
We’re in the Bahamas Baby!
We cleared in with the Bahamas Immigration and Customs officials, and the next day we continued on southeast to Shroud Cay in the Exuma Land a Sea Park, and its stunningly beautiful. And, the E/SE trades are building back in for at least two weeks, great conditions for us, but I’m sure glad we’re across the Stream and cruising the Bahamas.16