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Even before one of Greece’s best mathematicians, Archimedes, discovered buoyancy, ships’ captains have been navigating waterways around their own lands. Archimedes figured out that ships can float if they weigh less than the volume of water. A wooden ship displaces just enough water and sinks partly into the water as it moves.
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The Mesopotamians invented sails in 5,000 B.C. and the Egyptians sailed the Nile in 3,000. But it was the Phoenicians who made the first ocean voyage in 1,000 B.C. Next came steam-powered boats, the first launched from France in 1783, the propeller, the gasoline-powered boat, the first nuclear-powered submarine in 1955 and finally ocean liners such as the Queen Mary 2, the world’s largest ocean liner, which made its first voyage in 2004. The progress of ships and ship-building has been an adventure.
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Kon-Tiki and Heyerdahl
Another adventure was made with explorer, Thor Heyerdahl, who set out on an expedition in 1947 on a specially built raft called the Kon-Tiki, in order to discover how the Polynesian people arrived.
The Kon-Tiki was built in Peru using materials that would have been available to ancient South American Indians. Nine balsawood logs were lashed together with rope to make a vehicle about 45’ long and 18’ wide. The logs were covered in bamboo to make a simple deck; a hut was erected on top. Up until that time, natives had believed that the Polynesian people came to the islands in the South Pacific by way of Asia.
Generally people thought that Heyerdahl’s journey to prove they arrived by water –across the Pacific Ocean—was crazy folly and that he would get lost in the seas. 101 days after its departure, the truly epic voyage of 4,000 miles helped by the swift ocean currents and Heyerdahl’s theories about sailing made him a visionary.
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How did they all get where they were going? Early sailors got lost and the watery nightmare of being disoriented or vanishing happened more than can be imagined. Many sailors lost their way if they moved out of sight of land. The early ships’ travelers, which some might call reckless fools, often guessed their direction by something called dead reckoning. This methodology involved keeping an eye on the ship’s direction and speed.
The Chinese invented the magnetic compass in the 12th century. To navigate their course, they relied on inaccurate maps and more guesswork. Their speed was measured by throwing a float over the side of the boat tied to a knotted rope and they counted the knots to estimate speed. That’s why the word “knot" is synonymous with 1 nautical mile or 1.15 miles; (or in metrics, 1.84 km,) per hour.
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Where in the World?
Navigation got better in the 18th century using sextants to figure out latitude (how far north or south they were). The instrument measured the Sun or Moon and certain stars and they depended on guide tables called an almanac.
About the same time, systems to calculate longitude, which is the position east or west from a fixed point, was studied using clocks called chronometers" Navigators set the clock at noon by watching the sun at its highest point in the sky. Based on Greenwich Mean Time (GMT), a place in England with both longitude, latitude and knowing degree coordinates —a degree is 60 minutes and a minute is 60 seconds—they were able to estimate precise position by degrees.
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If ships were then sailing great distances and there are more of them on the high seas, how did they communicate? Before radio transmission, they had to have a way to talk with each other should there be danger such as an iceberg, pirates, shipwrecks and other disasters. Lights and flares could be used to impart danger and were effective at night, but by day sometimes more information was needed.
An American Army surgeon sent a memo to some British officers challenging them to invent some type of signaling. Wigwag, or flag telegraphy, was devised.
Marine signaling for ships began in the 1800s and has been revised and updated until the “International Code of Signals" was published. This code has been reprinted in almost every language.
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Flag Telegraphy Characteristics
Certain rules are common to all flag languages. For instance, flags are displayed high and always read from top to bottom. When several messages are hoisted, the way to read them is from the ship’s masthead, ending at the port yardarm (left side end).
Single letters are shown for urgent messages or commonly used signals. For example, the single letter C means “affirmative" (or yes). D means “Keep clear of me. I am maneuvering with difficulty." N is “negative" and O means “man overboard". V says that the ship needs “assistance."
You will note that the International Code is made up of pennant flags or flags that come to a point at the end. These enable a signalman to repeat a letter using another set of flags. If we were to spell out S-U-S-A-N, we would hoist the S, U, the first repeat flag, then A, and N.
In dire situations, the speed of flag hoisting was paramount. According to Captain Barrie Kent, training Signalmen was vital. He says, “This was done by what were called Marching Manoeuvres. Here each man represents a ship, the ‘Admiral’ with an appropriate flag, the others with ANSWER pennants. The ‘Admiral’ shouts out the flag signal, the ANSWER pennants are held out horizontally… until the signal is understood, then held up vertically until the Admiral shouts ‘Execute’ and off they go."
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More Tidbits, Signs and Symbols
- The difference between a boat and a ship is that a ship can carry a boat but not vice-versa.
- Ships are referred to as “she," because ships embrace and protect their crews, as a mother would her children. Ship is feminine in many languages.
- The symbolic ship christening was done by a priest in Roman times and he offered libamentum or libation to the gods. The drink was often a small vial of wine that he would pour over the vessel itself, or into the waters—perhaps to one of the deities below in the sea. Today they break champagne bottles on the bow.
- According to popular lore, the pineapple was placed on the front porch when a sailor had returned home from afar. It signaled that he was available to tell stories about his journey and the booty he brought back. Today it is a “Welcome Home" symbol in home decorating.
- Flag Institute: Flag Signaling at Sea
- Storm Heroes: Wig-Wag Flags, Flag Hoisting & Distress Signals
- NOVA Online: How a Sextant Works
- Mental Floss: Why Are Bottles of Champagne Smashed On New Ships?
- Woodford, Chris. Ships and Submarines: History of Invention. New York: The Brown Reference Group, 2004. Book.
- Biography: Thor Heyerdahl