There is a river in the ocean : in the severest droughts it never fails, and in the mightiest floods it never overflows ; its banks and its bottom are of cold water, while its current is of warm. It takes its rise in the Gulf of Mexico, and empties itself into Arctic seas. This mighty river is the Gulf Stream ; there is in the world no other such majestic flow of waters. Its current is more rapid than the Mississippi or the Amazon, and its volume more than a thou sand times greater.
Its waters, as far out from the Gulf as the Carolina coasts, are of indigo blue. They are so distinctly marked that their line of junction with the common sea-water may be traced by the eye. Often one-half of the vessel may be perceived floating in gulf-stream water, while the other half is in common water of the sea — so sharp is the line and such the want of affinity between those waters.
At the salt-works of France, and along the shores of the Adriatic, where the " salines are carried on by the process of solar evaporation, there is a series of vats or pools through which the water is passed as it comes from the sea, and is reduced to the briny state. The longer it is exposed to evaporation, the Salter it grows, and the deeper is the hue of its blue, until crystallisation is about to commence, when the deep blue puts on a reddish tint. Now, the water of the Gulf Stream is Salter than the shore water of the sea through which it flows, and hence we can account for the deep indigo blue which all navigators observe in Gulf Stream water off the Carolina coasts. The salt-makers are in the habit of judging of the richness of sea-water in salt by its colour ; the greener the hue, the fresher the water. We have in this, perhaps, an explanation of the contrasts which the waters of the Gulf Stream present with those of the Atlantic, as well as of the light green of the North Sea and other Polar waters ; also of the dark blue of intertropical seas, and especially of the Indian Ocean, which poets have described as the " black" waters.
What is the cause of the Gulf Stream has always puzzled philosophers. Many are the theories and numerous the speculations that have been advanced with regard to it. Late investigations are beginning to throw some light upon the subject, though all is not yet entirely clear. Modern ingenuity has suggested a mode of warming houses in winter. It is done by means of hot water. The furnace and the caldron are sometimes placed at a distance from the apartments to be warmed. On reaching their intended scene of action, the hot water pipes are flared out, so as to present a large cooling surface ; after which, they are united into one again, through which the water, being now cooled, returns of its own accord to the caldron. The cool water is returning and flowing in at the bottom of the caldron all the while that hot water is continually flowing out at the top.
Now, to compare small things with great, we have, in the warm waters which are contained in the Gulf of Mexico, just such a heating apparatus for Great Britain, the North Atlantic, and Western Europe. The furnace is the torrid zone ; the Mexican Gulf and the Caribbean Sea are the caldrons ; the Gulf Stream is the conducting pipe. Such an immense volume of heated water cannot fail to carry with it beyond the seas a mild and moist atmosphere. And this it is which so much softens the climate of France and the British Islands. Every west wind that blows, crosses this stream on its way to Europe, and carries with it a portion of this heat to temper there the northern winds of winter. It is the influence
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he Gulf of Mexico and stretches to the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean. The process of western intensification causes the Gulf Stream to be a northward accelerating current off the east coast of North America. At about 40°0′N 30°0′W, it splits in two, with the northern stream, the North Atlantic Drift, crossing to Northern Europe and the southern stream, the Canary Current, recirculating off West Africa.
The Gulf Stream influences the climate of the east coast of North America from Florida to Newfoundland, and the west coast of Europe. Although there has been recent debate, there is consensus that the climate of Western Europe and Northern Europe is warmer than it would otherwise be due to the North Atlantic drift which is the northeastern section of the Gulf Stream. It is part of the North Atlantic Gyre. Its presence has led to the development of strong cyclones of all types, both within the atmosphere and within the ocean.
The Gulf Stream is typically 100 kilometres (62 mi) wide and 800 metres (2,600 ft) to 1,200 metres (3,900 ft) deep. The current velocity is fastest near the surface, with the maximum speed typically about 2.5 metres per second (5.6 mph)
Benjamin Franklin became interested in the North Atlantic Ocean circulation patterns. In 1768, while in England, Franklin heard a curious complaint from the Colonial Board of Customs: Why did it take British packets several weeks longer to reach New York from England than it took an average American merchant ship to reach Newport, Rhode Island, despite the merchant ships leaving from London and having to sail down the River Thames and then the length of the English Channel before they sailed across the Atlantic, while the packets left from Falmouth in Cornwall?[3]
Franklin asked Timothy Folger, his cousin twice removed (Nantucket Historical Society), a Nantucket Island whaling captain, for an answer. Folger explained that merchant ships routinely crossed the then-unnamed Gulf Stream—identifying it by whale behavior, measurement of the water's temperature and the speed of bubbles on its surface, and changes in the water's color—while the mail packet captains ran against it.[3] Franklin worked with Folger and other experienced ship captains, learning enough to chart the Gulf Stream and giving it the name by which it is still known today. He offered this information to Anthony Todd, secretary of the British Post Office, but it was ignored by British sea captains.[3]
Franklin's Gulf Stream chart was published in 1770 in England, where it was mostly ignored.[4] Subsequent versions were printed in France in 1778 and the U.S. in 1786
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In the western Atlantic, the current’s deep-blue water, with its higher temperature and salinity, is readily distinguishable from surrounding waters, particularly along its well-defined western margin. The eastern edge gradually moves seaward as the current moves northward. The water between the current and the North American mainland, with its lower salinity and temperature, forms a boundary known as the Cold Wall. This water, overlying the continental shelf, frequently has a southerly flow, counter to that of the Florida Current.
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In the western Atlantic, the current’s deep-blue water, with its higher temperature and salinity, is readily distinguishable from surrounding waters, particularly along its well-defined western margin. The eastern edge gradually moves seaward as the current moves northward. The water between the current and the North American mainland, with its lower salinity and temperature, forms a boundary known as the Cold Wall. This water, overlying the continental shelf, frequently has a southerly flow, counter to that of the Florida Current.
Crossing the Gulf Stream
2009 April 1
A better understanding of the legendary ocean current can make your passage faster and safer
The Gulf Stream is part of a current that circles the Atlantic Ocean from the Americas to Europe. Ocean currents are caused by various factors: differences in water temperature and salinity, the varying height of seamounts and the ocean floor, and local winds. The Coriolis force, caused by the Earth's rotation about its axis, also has a telling effect on this moving river set within the more static waters of the oceans.
Figure 1 shows the various oceanic currents over the North and South Atlantic. From the Caribbean Sea, the stream flows northward through the narrow Straits of Florida, achieving currents as high as 5 knots. The Gulf Stream then continues to roughly follow the contours of the eastern coastline north as far as Nova Scotia and Newfoundland.
The Labrador Current flows southerly from Greenland and Newfoundland. The intersection of these cold waters and the warm Gulf Stream is a factor in the easterly bend of the stream, and is also responsible for the fog seen in the Grand Banks zone. Upon meeting the Labrador Current, the Gulf Stream splits. One branch proceeds toward Greenland, another more toward Iceland, while the primary segment flows almost due east toward Europe. This forms the "north wall" of the stream. It eventually bisects again near the European coast; the northern branch affects the shores of northwest Europe, warming the bitter cold waters there. The more predominant southern branch flows southeastward along the European coast and Africa, becomes known as the Portuguese current, and then turns westerly toward the Caribbean Sea to begin the cycle again.
The Gulf Stream waters actually generate their own mini-climate, as warm air rises and generates distinct areas of low pressure. The Gulf Stream waters are a breeding ground for many of the severe storms experienced by those living along the eastern seaboard.
Anyone crossing the Gulf Stream from east or west, or across the north wall, is advised to exercise caution and careful planning to ensure favorable conditions. When done properly and rough weather is avoided, the major concern becomes the prominent set to be expected when the current flows across one's course.
As the stream varies in width, from about 30 miles off the coast of Florida to more than 80 miles farther north, it pays to make crossings at the narrowest point within a reasonable distance of the course line, and to make good speed while doing so to lessen the current set and to get across before inclement weather can develop. Whenever current flows against wind, waves can build quickly and become steeper than normal. In this manner, waves in the Gulf Stream grow precipitously in a short span of time, within hours, after a strong opposing wind develops, as seen in the photo on the left.
Wind of less than around 20 knots, even out of the northern quadrants, can make sailing uncomfortable, but don't usually cause dangerous waves. The key is to avoid the Gulf Stream current when wind out of a northern quadrant in excess of 15 knots blows against the direction of the current. These winds can result from a low-pressure system, passage of a cold front, or interaction between high and low pressures.
The other important consideration involving the Gulf Stream is the eddies that circulate around it. Figure 2 above shows that warm water eddies are often seen north of the stream, and cold water eddies develop to its south. Warm eddies circulate in a clockwise direction; currents around cold eddies are counterclockwise. The strategy is to position the boat in that portion of an eddy that favors rather than opposes your course line, taking advantage of up to a knot per hour boost in speed for up to 30 hours! At the least, avoid getting caught in the wrong side of an eddy, which slows the boat accordingly.
Consider the directional flow of the eddy waters; if that flow counters wind direction, waves can build much like they do in the Gulf Stream proper, although usually not as much.
When preparing to cross the Gulf Stream, certain steps should be taken. These steps should include the following:
Study the weather
" Download and interpret weather chart information on your own or get routing assistance from professional services. Concentrate on forecast wind directions at the time you'll be crossing the stream.
" Download the latest positions of the Gulf Stream and associated eddies. I have gotten this information from Jenifer Clark's Gulfstream (http://users.erols.com/gulfstrm) and NOAA (http://polar.ncep.noaa.gov/ofs). Positions of the Gulf Stream proper and eddies change on a daily basis. Eddies generally drift toward the south or southwest, and their positions are only accurate for about three days from when they're issued.
" After departure, monitor the weather closely, both by electronic chart downloads, sea buoy data, and by paying attention to local conditions. Do not entrust your forecasts solely to downloaded charts; what you actually experience can differ from those predictions.
Manage your course
" Allow for the expected set of the current. If the area you intend to cross is approximately 60 miles wide, consider flow in the innermost 20 miles of the current to be the fastest. I usually allot 1 knot per hour of set from my course line, and compensate before entering the current. Calculate the stream width and number of hours expected to cross it, and then enter the stream up current appropriately.
" Set a waypoint where you'd like to enter the stream to account for current set.
Monitor the crossing
" Watch the track line as you cross. Don't be surprised if you make 30 or even 40 degrees off your course line as the current exerts its presence. Do not steer to counter the current set; maintain a course directly across its flow.
Figure 1 shows the various oceanic currents over the North and South Atlantic. From the Caribbean Sea, the stream flows northward through the narrow Straits of Florida, achieving currents as high as 5 knots. The Gulf Stream then continues to roughly follow the contours of the eastern coastline north as far as Nova Scotia and Newfoundland.
The Labrador Current flows southerly from Greenland and Newfoundland. The intersection of these cold waters and the warm Gulf Stream is a factor in the easterly bend of the stream, and is also responsible for the fog seen in the Grand Banks zone. Upon meeting the Labrador Current, the Gulf Stream splits. One branch proceeds toward Greenland, another more toward Iceland, while the primary segment flows almost due east toward Europe. This forms the "north wall" of the stream. It eventually bisects again near the European coast; the northern branch affects the shores of northwest Europe, warming the bitter cold waters there. The more predominant southern branch flows southeastward along the European coast and Africa, becomes known as the Portuguese current, and then turns westerly toward the Caribbean Sea to begin the cycle again.
The Gulf Stream waters actually generate their own mini-climate, as warm air rises and generates distinct areas of low pressure. The Gulf Stream waters are a breeding ground for many of the severe storms experienced by those living along the eastern seaboard.
Anyone crossing the Gulf Stream from east or west, or across the north wall, is advised to exercise caution and careful planning to ensure favorable conditions. When done properly and rough weather is avoided, the major concern becomes the prominent set to be expected when the current flows across one's course.
As the stream varies in width, from about 30 miles off the coast of Florida to more than 80 miles farther north, it pays to make crossings at the narrowest point within a reasonable distance of the course line, and to make good speed while doing so to lessen the current set and to get across before inclement weather can develop. Whenever current flows against wind, waves can build quickly and become steeper than normal. In this manner, waves in the Gulf Stream grow precipitously in a short span of time, within hours, after a strong opposing wind develops, as seen in the photo on the left.
Wind of less than around 20 knots, even out of the northern quadrants, can make sailing uncomfortable, but don't usually cause dangerous waves. The key is to avoid the Gulf Stream current when wind out of a northern quadrant in excess of 15 knots blows against the direction of the current. These winds can result from a low-pressure system, passage of a cold front, or interaction between high and low pressures.
The other important consideration involving the Gulf Stream is the eddies that circulate around it. Figure 2 above shows that warm water eddies are often seen north of the stream, and cold water eddies develop to its south. Warm eddies circulate in a clockwise direction; currents around cold eddies are counterclockwise. The strategy is to position the boat in that portion of an eddy that favors rather than opposes your course line, taking advantage of up to a knot per hour boost in speed for up to 30 hours! At the least, avoid getting caught in the wrong side of an eddy, which slows the boat accordingly.
Consider the directional flow of the eddy waters; if that flow counters wind direction, waves can build much like they do in the Gulf Stream proper, although usually not as much.
When preparing to cross the Gulf Stream, certain steps should be taken. These steps should include the following:
Study the weather
" Download and interpret weather chart information on your own or get routing assistance from professional services. Concentrate on forecast wind directions at the time you'll be crossing the stream.
" Download the latest positions of the Gulf Stream and associated eddies. I have gotten this information from Jenifer Clark's Gulfstream (http://users.erols.com/gulfstrm) and NOAA (http://polar.ncep.noaa.gov/ofs). Positions of the Gulf Stream proper and eddies change on a daily basis. Eddies generally drift toward the south or southwest, and their positions are only accurate for about three days from when they're issued.
" After departure, monitor the weather closely, both by electronic chart downloads, sea buoy data, and by paying attention to local conditions. Do not entrust your forecasts solely to downloaded charts; what you actually experience can differ from those predictions.
Manage your course
" Allow for the expected set of the current. If the area you intend to cross is approximately 60 miles wide, consider flow in the innermost 20 miles of the current to be the fastest. I usually allot 1 knot per hour of set from my course line, and compensate before entering the current. Calculate the stream width and number of hours expected to cross it, and then enter the stream up current appropriately.
" Set a waypoint where you'd like to enter the stream to account for current set.
Monitor the crossing
" Watch the track line as you cross. Don't be surprised if you make 30 or even 40 degrees off your course line as the current exerts its presence. Do not steer to counter the current set; maintain a course directly across its flow.
" Monitor the water temperature when approaching, traversing and leaving the Gulf Stream. For example, the sea temperature may be 76.9 degrees F, then suddenly increase to 79.8 as you enter the fringes of the stream. It will climb to temperatures of up to 85 degrees in the middle sections, and then gradually fall as you near the other side.
You may also witness the following in or while approaching the Gulf Stream:
" Cumulus clouds above the warm waters
" A distinct line of sargasso weed or difference in appearance that separates the stream from the still ocean waters (as in the photo above)
" Deeper blue hue to the water
" Dolphins that follow the stream in search of food will make contact and play with boats more often near the stream
" Fog can develop if the warm water flows beneath cooler air
" Localized squally weather
Any boat crossing the Gulf Stream should be well fitted out with storm sails and adequate safety equipment and those on board are advised to know how to cope with heavy weather situations. If done correctly, under the right weather conditions, Gulf Stream crossings are not dramatic events.
In the 29 passages I've taken across the Gulf Stream, I've only encountered storm conditions on one occasion. I was not then a captain, and would not have sailed were I aware that a strong cold front would approach the area shortly after our departure from New York Harbor. Those three days spent in 30- to 40-foot waves and Force 9 wind provided memories to last a lifetime, and taught a lot of lessons about ocean sailing. Forethought and planning has prevented a reoccurrence of that incredible experience ever since.
You may also witness the following in or while approaching the Gulf Stream:
" Cumulus clouds above the warm waters
" A distinct line of sargasso weed or difference in appearance that separates the stream from the still ocean waters (as in the photo above)
" Deeper blue hue to the water
" Dolphins that follow the stream in search of food will make contact and play with boats more often near the stream
" Fog can develop if the warm water flows beneath cooler air
" Localized squally weather
Any boat crossing the Gulf Stream should be well fitted out with storm sails and adequate safety equipment and those on board are advised to know how to cope with heavy weather situations. If done correctly, under the right weather conditions, Gulf Stream crossings are not dramatic events.
In the 29 passages I've taken across the Gulf Stream, I've only encountered storm conditions on one occasion. I was not then a captain, and would not have sailed were I aware that a strong cold front would approach the area shortly after our departure from New York Harbor. Those three days spent in 30- to 40-foot waves and Force 9 wind provided memories to last a lifetime, and taught a lot of lessons about ocean sailing. Forethought and planning has prevented a reoccurrence of that incredible experience ever since.
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