SAITO CHALLENGE 8 DAILY LOG (2008-2011): Day 590 [May 15/10] -- Preparing to cross the Doldrums

Today's Report

May 15/10 0800 JST / 1700 local

Position:

00°11'S, 94°36'W (Just below and parallel to Equator)

Under fair winds he was able to make 120 nm mostly under sail during the period, as he considers his strategy for crossing the Doldrums, the band of "dead air" just above the Equator.

The Doldrums are an approximately 400 nm-wide virtually windless band that can be seen on ClearPoint running parallel to the Equator. The lower edge is about 100 nm north of Saito-san's present position. About 400 nm above that is the bottom edge of the easterly trade winds.

With the help of ClearPoint we're trying to judge where the Doldrums band might be thinner within the next few hundred miles on his route west. At some point he will need to turn directly north and motor across the expanse of weak and variable winds. In this area of dead air, the sails will be mostly useless.

In fact, due to the erratic flailing of the sails under weak winds and boat rolling, Saito-san must motor in order to keep the rigging and sails from becoming damaged through uncontrolled slamming of the main boom and increased line abrasion.

On ClearPoint localized high pressure waves can be seen passing through, so that the thickness of the band changes throughout the day and night. The difference in the width of the dead air band is as much as 100 nm as these "mini highs" move through from west to east.

Below: The cross is NBSDIII's position; the hand symbol points to the edge of the easterly trade winds, with favorable winds blowing constantly from the east in the low teens. White and lighter patches show areas of low wind (2-3 kt) and no wind. Arrows indicate weak and variable wind direction. The band is about 600 miles wide as shown on ClearPoint [Click to enlarge]