In 1513, Ponce de Leon was the first to note a current that was faster than his ships, but did neither explored it nor documented its location. What de Leon discovered is the Gulf Stream.
The Gulf Stream is a warm current flowing from the Gulf of Mexico, around Florida and up along the Atlantic Coast of North America. Off Newfoundland, Canada’s most eastern province, it bends east. North of the Azores, it splits into the North American Drift and the Canary Current. The North American Drift flows north toward Ireland while the Canary Current goes south toward the northwest coast of Africa.
On average the current moves at 5 knots. What de Leon discovered was, by the 17th and 18th Centuries, well known by American merchant ship captains. Time is money in the shipping business and the extra five knots meant one could deliver cargos to Europe faster. By avoiding the Gulf Stream, ships could sail from Europe to the Colonies in less time.
According to searoutes.com, it is 3,342 nautical miles from New York to London. Assume a sailing ship could sail at 10 knots in a straight line without having to tack back and forth across the wind line. By taking advantage of the Gulf Stream’s current, the crossing could be made in 334.2 hours or 14.25 days. At 15 knots, the trip is only 9.3 days long.
In 1768, while working in London for the Royal Mail as its Deputy Postmaster for the American Colonies, Ben Franklin noticed that American owned eastbound ships carrying mail crossed faster than those with British owners. Merchant ship captain Tim Folger told his cousin – Ben Franklin about the current. Folger took the information he collected from American fishermen, cargo and whaling ship captains and made Franklin a sketch.
When Franklin brought what he called the “Gulph Stream” to the attention of his employer, he was told, “Royal Mail captains were too wise to be counseled by American fishermen.” Not only did the Royal Mail ignore its effect, so did the Royal Navy.
Once the American Revolution began, Franklin provided the data he’d gathered along with copies of Foley’s original sketch to American merchant and Continental Navy ship captains. In Paris, he shared his notes with the French Navy who used it reduce their Atlantic crossing times, often surprising the British.
After the war, Franklin printed the first chart of the Gulph Stream in 1785. While it is not accurate by today’s hydrographic standards, Franklin and Foley got most of it right including the Gulf Stream’s location, direction and circular motion.