Thermal shock…


17 January 2012

The last long station of this “Panama-Savannah” leg has just begun in briskly cool weather that Tara has not experienced for months. On deck the scientists seem to miss the blazing sun that followed us since Panama; but below Tara’s hull the current carrying us is still under the sign of the tropics.
Entering the Gulf of Mexico, we went from suffocating heat to mild, pleasant summer weather. But this weekend, after passing the famous Florida Cape and heading north, the thermal shock was more violent.
On deck people are now wearing vests and warm jackets, and blankets appeared in the cabins. In less than 48 hours, the temperature has dropped 10 degrees.  And this is only the beginning… But curiously, under our feet, the water has retained “tropical time”, staying about 25 degrees; but only a couple of kilometers away, nearer to the coast the water temperature is only 15 degrees.
Between the last station in the Gulf of Mexico and this one, with Florida to the West and the Bahamas to the East, the current carrying us retains almost all of its heat. A current that our scientists have not stopped studying between these two stations.
Throughout the week, as if in a routine, each morning was devoted to a short station “in miniature”. The program consisted of: CTD (physico-chemical water data), Bongo (net used to catch largest species between the surface and 500 meters), sometimes TSRB (Tethered Spectro Radiometer Buoy, sensors used to analyze ocean color), and finally surface water sampling to study phytoplankton and to catch specimens for Gabriella to photograph in the dry lab.
Needless to say, the current that’s been carrying us all along this leg and will soon become the Gulf Stream has been scrutinized every day by the scientific team. And the sailors, even without studying it, have certainly been experiencing this famous current, especially Loïc. “It’s obvious, running on 2 motors against the wind, ordinarily we’d make an average of 5 knots. When we passed through the Florida channel, we were making 8 and a half! This will put us ahead of schedule for this last week at sea, even though we’ve stopped for the 2 days and nights of this long station.
Finally, everyone is counting on this benevolent current to take us safely to harbour by the end of the week. In this case, Savannah.
Yann Chavance