Response from a Reader: Sailing into the Atlantic – Part III

Continuing from the previous posts regarding a comment sent in by a reader asking for our response to his friend’s reaction to one of our articles about sailing off the Arabian coast and into the Indian Ocean, and asking for our response. Listing seven factors in the previous two posts, we continue here with #8. 
   This means that Nephi’s ship to have crossed the Somali Current moving south would have had to reach that point between December and March, likely January or February, probably leaving the coast of Arabia sometime in middle to late January. Thus, it would not be the harvest that would determine when they left, but when the currents and winds would be right for the voyage.

Also being ignored is the Great Whirl off the Somali coast and the Socotra Gyre, which undergo dramatic changes in response to the seasonal reversal of the monsoon winds—and both of these are right in the path of Lehi’s voyage away from Arabia and toward the Indian Ocean. Located over the Somali Basin, west of the Carlsberg Ridge and the Arabian Sea, two areas of warm saline surface water of southern offshore origin enters the northern Somali Basin within a 75-mile-wide swift current between the Great Whirl and the Socotra Gyre. 
This whirl is one of the ocean's weirdest currents, a giant clockwise eddy that emerges every summer off the coast of Somalia. The swirling waters shift sea-surface temperatures, influencing moisture carried to Asia by monsoon winds.
    For more than 100 years, sailors have known the Great Whirl arrived with the onset of monsoon winds in early June and disappeared about one month after the winds died down in August are some of the strongest on the planet, blowing at a constant 30 mph. It is so unusual, and because the massive vortex has a powerful impact on local climate, including the monsoon winds, scientists are studying how and why the Great Whirl appears. In fact, it has been found to be even more closely linked to the monsoon than previously thought, but through the ocean, not through the atmosphere. A new study in the January 28 Geophysical Research reveals the clockwise current spins up nearly two months before the winds arrive. Thus, the ocean waves bring in energy well before the wind forcing sets in and this sign provides a warning even before the monsoon hits.

Top: The Great Whirl; Bottom: The flanking eddies swirling counter-clockwise around the clockwise swirling Great Whirl

    The Great Whirl is an exceedingly large anti-cyclone: 185 miles across and about 3,280 feet deep, with waters moving clockwise, and the the surface current (the fastest part) clipping along at a speedy 4.5 mph
    The annual arrival of these oceanic “Rossby Waves” in April triggers the clockwise circulation, nearly two months before the monsoon winds start. The waves themselves are disturbances caused by the previous monsoon winds, and is like a feedback from one monsoon to the next via these planetary wave processes. The vortex lasts for roughly 166 days each year, yet there seems to be no predictable pattern to its location and orientation.
    Over the years, the Great Whirl's wanderings were caused by its own mini-cyclones, and as the current spins, it creates two to three flanking counter-clockwise cyclones along its flanks that are opposite to the Great Whirl. The interaction between the smaller cyclones and the "mother current" makes the Great Whirl move and shift around in response.
    The other key region for the exchange of water masses is the passage between Somalia and Abd al Kuri. There, the total northward transport was 13 Sv (1 Sv is equivalent to 3.2 million cubic feet per second) of upwelled IEW water close to the surface, and ASW (Arabian Sea Water) underneath. The point of this is that during much of this time, these factors interfere with movement off the Arabian coast and into the Sea of Arabia of a sailing vessel “driven forth before the wind,” moving south toward Madagascar. Once again, the overlap eliminates the sailing of Nephi’s ship until around mid to late January and February.
8. “… and around to the Atlantic…”

The area through which many people think Lehi could have sailed to make landfall on the east coast of the Land of Promise (or penetrate up a river, such as the Mississippi), would take him around what is today called the Cape of Good Hope off the point of South Africa, but was originally called the Cape of Storms because of its turbulent currents, winds, and numerous storms. This shows where four currents come together at this point: the Warm Agulhas coming down from the equator, the Cold Benguela coming up from the Antarctic, the Angola coming down the coast and forced outward by the Benguela, and the numerous Tourbillons, which are small, but powerful currents that flow in a circular manner (vortex flow), forming swirl vortexes, like a whirlwind in the sea. Because of the powerful Benguela, other currents are turned aside—the Agulhas is forced back upon itself, creating enormous difficulties even for experienced mariners who try to sail southward around the Cape, and in the day of Sail, was feared by all marners

     Response: First of all, to get into the Atlantic, one would have had to sail around what is today called the Cape of Good Hope, but called the Cape of Storms in the days of the Age of Sail because of the tumultuous currents and winds that arise off the Cape. We have written many times about this area and that it was the worst graveyard of sailing ships anywhere in the world with hundreds of ships lost trying to round it and sail out into the Atlantic.
    This rocky headland on the Atlantic coast of the Cape Peninsula of South Africa, however, is not the southern-most point of Africa—this misconception exists because it was once believed to be the dividing point between the Atlantic and Indian Oceans. However, the southernmost point is actually Cape Agulhas, about 90 miles to the east-southeast.
    Known for the stormy weather and rough seas encountered there, the cape is situated at the convergence of the warm Mozambique-Agulhas current from the Indian Ocean and the cool Benguela current from Antarctic waters, forcing the Agulhas to turn back on itself, causing difficult sailing from the Indian Ocean around the Cape and into the Atlantic—a point that fluctuates between Cape Agulhas and Cape Point, which is about ¾ of a mile east of the Cape of Good Hope.
    In fact, when following the Atlantic coastline down the western side of the African continent from the equator, the Cape of Good Hope marks the point where a ship begins to travel more eastward than southward. Thus, the first modern rounding of the cape in March 1488 by Portuguese explorer Bartolomeu de Novaes Dias was a milestone in the attempts by the Portuguese to establish direct trade relations with the Far East (although Herodotus mentioned a claim that the Phoenicians had done so far earlier (Phoenician sailors under Necco II sailing around Africa).

Dias, a member of the court of king João II, of Portugal (João and his predecessors had obtained navigational intelligence, including a 1460 map from Venice that showed the Indian Ocean on the other side of Africa—a remarkable find for the Portuguese and what prompted their continual attempts to round the southern tip of the continent), and was a superintendent of the royal warehouses before embarking on this voyage in the warship São Cristóvão, called the cape Cabo das Tormentas ("Cape of Storms,” Dutch: Stormkaap), which was the original name of the "Cape of Good Hope because of the horrendous weather conditions in that area, but John II of Portugal renamed it Cape of Good Hope because its discovery was a good omen that India could be reached by sea from Europe.
(See the next post, “Response from a Reader: Sailing into the Atlantic – Part IV,” for a continuation with item #9 and the continuation of this response)