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-   -   First Leg of an Atlantic Crossing (http://www.sailnet.com/forums/seamanship-articles/19098-first-leg-atlantic-crossing.html)

Michael Carr 01-31-1998 07:00 PM

First Leg of an Atlantic Crossing
 
<HTML><!-- eWebEditPro 1.8.0.2 --><TABLE width="100%" border=0><TBODY><TR><TD align=left><P>Conveniently located some 500 miles southwest of Gibraltar, the Atlantic island groups of Madeira, Canary and Cape Verde are ideally placed stepping stones for a voyage from the Mediterranean to the Caribbean. These islands lie along the northeast trade winds on the route favored by sailors crossing back west.</P><P>Along with their natural beauty and favorable trade-wind weather, these islands also have their own special winds and ocean currents, resulting from their location close to the convergence of the northeast and southeast trade winds, an area called the Inter Tropical Convergence Zone.</P><P><B><FONT color=darkgreen>Madeira Islands</FONT></B><BR>The Madeira Islands lie 345 miles off the Morocco coast, straddling 32 and 33&nbsp;degreees north latitude and 16 to 17 degrees west longitude. The island group, a part of Portugal, consists of the island of Madeira, the island of&nbsp;Porto Santo and the three-island group&nbsp;Ilhas Desertas.</P><P>The Madeira Archipelago is exceedingly beautiful with high mountains peaks and large valleys. Along the south coasts, the land slopes gradually to the interior, while the north and west coasts are high and bold. But there are a few well sheltered harbors, the most known are Funchal, located on the south side of Madeira, and&nbsp;Baia de&nbsp;Porto Santo, on the south side of&nbsp;Ilha de&nbsp;Porto Santo.</P><P>The Madeira Island are in the main southwesterly flowing Canary Current. Like a rock in the middle of a stream, the islands split the current, which flows around the islands. The current breaks at&nbsp;Porto Santo then rejoins south of Madeira. Eddies and swirling that extends some 4 or 5 miles off the coast occurs at this convergence. As unnerving as these eddies may be when first seen, they are in fact in deep water.</P><P>Madeira Islands, lying in the northeast trade-windbelt, do, indeed, experience year-round northeasterlies, but with an exception. In the summer and periods of hot weather, an afternoon sea breeze--a southerly--often builds, over-riding the northeast trade winds. You also will not find a northeaster on the south side of Madeira Island where, due to the island's mountains, the wind condition is actually calm.</P><P>Rising up to 6,141 feet, Madeira's mountain range extends east- west for the length of the island. Funchal is the major port and has an extensive marina which can accommodate yachts up to 60 feet and 13- foot draft.</P><P>The three-island Ilhas Desertas group is volcanic and rugged with steep cliffs and dangerous shoals lying up to 2 miles to seaward. There are few good anchorages in this group, which, in general, should be approached with caution.</P><P>An interesting underwater aspects of the Madeira Islands is the chain of sea mounts that extends out from the islands in a northeast direction. Recent oceanographic research indicates shoaling in their vicinity with resultant eddies and turbulence. Though most yachts will find little difficulty in passing over them, these sea mounts are avoided by ships. Notice to Mariners should be consulted prior to departure from Gibraltar or other European ports.</P><P><B><FONT color=darkgreen>Canary Islands</FONT></B><BR>The Canary Islands are a group of seven islands that are governed as a province of Spain. They extend over a 240-mile area, lying in an east-west direction at near 29 degrees north latitude. These islands are volcanic, with high peaks, which are snow-covered most of the year.</P><P>Pico de Teide, on the Island of Tenerife, is the highest. Rising to 12,269 feet, it makes for an impressive landfall. The Canary coastline is largely cliff and rock, with few lees. Due to the height of these islands, you can expect a wind shadow of up to 30 miles out on the leeward side. (Note: Calms and variable winds routinely extend from the lee side of an island to a distance eight times an island's maximum height on the lee side of an island.) Wind shadows have actually been detected as far downwind as 100 miles from mid-ocean islands. Determining how to pass such islands is a significant tactical decision. Around-the-world racers passing through the Atlantic give careful consideration to how they will pass the Canary and Verde islands.</P><P>La Palma, the most northwest of the Cararies, is frequently enveloped in fog, caused by the meeting of the warm moist Atlantic atmosphere and cooler Canary currents flowing through. There is a general haze that seems to set over the Canaries, making them a misy landfall that is not visible from afar. These islands also experience heavy swells and a strong west and southerly wind called El Caldereto. This wind, which can reach up to hurricane velocity, is often spurred by a passing mid-latitiude low pressure system to the north. Winds here tend to funnel, sometimes racing up to 15 to 20 knots faster than winds north or south of the islands. The current, on the other hand, is not much of a factor as it sets to the west at a knot.</P><P>The typical Canary breeze is northeast, with the exception of when a low pressure system passes to the north, typically in winter. This causes strong southerlies to blow and also brings large swells into harbors on the island's south side. It also causes formation of haze, reducing visibility to 5 miles or less.</P><P>There are several off-lying dangers near the Canaries that should be mentioned here:<OL><LI>Roca del Este (29N/13W) is a barren rock 195 feet high. It is steep except on the southeast side, which has submerged rocks. <LI>Conception bank (30N/13W), at 512 feet deep, is known for local upwellings and currents. <LI>Dacia sea mount (31N/14W) lies on the course used by vessels transiting between Canaries and Gibraltar, and has a depth of 251 feet. </LI></OL><P><B><FONT color=darkgreen>Cape Verde Islands</FONT></B><BR>Archipelago de Cabo Verde (15N/17W) lies 320 miles off the African coast and consists of 10 islands. The islands were once a territory of Portugal but are now fully independent. These islands are of volcanic origin and, like the Canaries, lie within the northeast trade-wind belt. There are two principal ports within the island chain: Porto Grande, and Porto da Praia. Coasts are bold but rocks and shoals are prevalent. Cruising guides recommend staying at least 1 mile from shore.</P><P>In winter when trade winds become well developed, dust from the African continent becomes airborne wafting out into this Atlantic route. The dust is so prevalent it can cover the decks as well as reduce visibility down to only a few hundred yards. In this condition, distances are often difficult to judge and land is difficult to see.</P><P>Gales and mid-latitude weather systems are rarely experienced here but squalls can blow down from the tall mountains, which reach heights of up to 6,531 feet. Mountain-induced winds are often encouraged by strong trade winds.</P><P>Tide range is approximately 4 feet and tidal currents are weak and variable. There is one off-lying danger near the Cape Verde islands, a shoal named Baixo Joao Leitao, located at 15.8N/23.2W. It consists of coral and shell and is usually awash. Breakers can normally be seen on the bank except when the wind is calm. Fishing vessels are often seen in its proximity.</P><P><B><FONT color=darkgreen>Onward to the Caribbean</FONT></B><BR>Departure for the Caribbean from Madeira, the Canaries or the Cape Verde Islands is natural as you are already within the northeast trade winds and the only real decision is where to place yourself within this wind belt. From either the Canaries or the Cape Verde Islands, it is 2,500 miles to the windward islands of the Caribbean. On a 50-footer, this is an 18-day trip if an average of 5.5 knots is kept. Pilot chart records show that following this course will bring broad-reaching conditions 61percent of the time and running conditions 39 percent of the time. How about that for ideal sailing! <P></P></TD></TD></TR></TBODY></TABLE></HTML>


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