Battle in the Doldrums

01 November 2007

Fedor and his Open 85 yacht “Trading Network Alye Parusa” is sailing across the Doldrums area in very unstable weather system with rapid gusts 35+ knots, heavy rain. The air is very thick and humid. The system is moving west bringing more S-S winds for Fedor. According to the forecast – Doldrums at this particular time are wide (500 miles). Sails handling is quite difficult as winds vary from 05 knots to gale force. Obvious intention is to get out of this area as soon as possible but Fedor must be careful not to overpower his 110 ft mast with extra sails. To take a reef on 220 sq.m main sail is not one minute job for single-handed sailor. Hope Fedor will have enough patience to cross the Doldrums safely.  

Here is detailed report from project weather router Lee Bruce:

“Fedor is crossing the Intertropical Convergence Zone (ITCZ), which is often referred to as the “Doldrums” because there often are pockets of light wind across this region, and sailors sometimes are stopped completely, until enough wind arrives to move them again.  The ITCZ is the boundary where the northeast and southeast trade winds meet.  This convergence of air produces upward motion in the atmosphere, and the hot, moist conditions result in widespread squalls and thunderstorms (shown as bright white areas on this photo). The satellite photo above was taken at 1215UTC on 3 November, with Fedor just approaching 10N.  A band of squalls is nearby, and that is causing [email protected]@[email protected]@s wind to be highly variable in direction and speed.  Wind speed can vary from near zero, to gale strength (35kt or higher) in a brief period. And wind direction can swing wildly.

This photo also shows a narrow band of squalls near 3-4N latitude (I marked the band with a dashed black line).  That band of squalls marks the shift to southeast trade winds, so you can see that Fedor has many miles to cover before he is out of the Doldrums.  The wind shift line does drift north and south over time, and the forecast has that shift line moving north over the next few days.  So, perhaps Fedor will find the southeast trade winds before he reaches 3N. 

This map displays wind speed and direction as measured by the satellite-based QuikSCAT sensor.  I marked [email protected]@[email protected]@s position as of the time of this data (2 Nov, 2000UTC; Fedor was just north of 11N at the time). 

The QuikSCAT works like a radar, by sending a signal to Earth and then measuring the returned signal after it has been affected by the roughness of the ocean (more wind means more waves and spray, which means less signal returned).  In areas of heavy rain, the signal gets affected so much that the data are not reliable, and can result in errors like too much wind speed being registered.  The system marks those questionable winds as black wind barbs so that we know not to trust the data too much.  The benefit is that we get to see where the heavy rain is, without looking at a separate weather satellite photo.

Fedor will have to stay alert for wind shifts while he crosses the Doldrums.  And when the wind is very light, he has to be careful not to use too much sail, because he may not have time to reduce sail before a big gust of wind.  The air is hot and humid, so this region is very uncomfortable.  About the only good thing is that African dust that collected on the boat on the way south will be washed away by the rain!



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