- Dry Dock
A Phoenician finds a new way to launch ships.
The dry dock was invented in Egypt by a Phoenician, some years after the death of Ptolemy 4 Philopator, who reigned from 221 to 204 B.C.E. His method of launching a ship consisted of digging a trench under it close to the harbor, then making a channel from the sea to fill the excavated space with water.
Dry docks continued to be used throughout antiquity. In Europe the first dry dock was commissioned in 1495 by King Henry 8 at Portsmouth, England. Dry docks are mainly used tor the maintenance and repair of ships, and more rarely for their construction because the time required to build a ship is so long. While early dry docks were often used for launching ships, slipways are more frequently used in modern times.
There are two types of dry docks: graving docks, where “graving” is the term for scouring a ship's bottom, and floating dry docks. The graving dry dock consists of a water-filled narrow basin, usually made of concrete, with gates that can be opened and closed, into which a vessel may be floated. The water is then pumped out, leaving the vessel supported on blocks, so that the ship can be serviced. When the work is finished, water is let back into the dock and the ship refloated. Earlier dry docks were built in the same shape as the ships that were to be docked there, but more recently, graving docks have been built in a box-shape, to conform to boxier ship designs.
A floating dry dock is usually built of hollow steel. The dock is first submerged, the ship is brought into its channel, and the dock is then floated by removing ballast from the hollow floor and walls. The fully drained dock supports the craft on blocks attached to the dock floor. Floating dry docks are usually operated in sheltered harbors to avoid wave damage.
SEE ALSO: ENCLOSED HARBOR, STEEL, REINFORCED CONCRETE, AUTOMATIC FLOUR MILL
- Dugout Canoe
Sometimes there Is no real need to be clever, or complex, or even particularly sophisticated when it comes to inventions. Sometimes simple wins.
This is definitely the case with the dugout canoe. The people of 7500 B.C.E. needed a way to travel on water, but many of the materials used in the very earliest boatbuilding still lay a long way ahead in the future. So they came up with a simple answer using the technology that was accessible to them.
The dugout canoe is, in its most basic terms, a hollowed-out log, nothing more than a tree trunk laid down on its side and its interior removed. All that was required was that the hollowed log had to be big enough for at least one person to sit inside, and the wood had to be sound, not rotten. If a log fulfilled these two criteria, It was a potential canoe.
As these vessels were made before the invention of metal tools, the logs were hollowed out using a Controlled fire and a sharpened rock implement (known as an adze) to scrape away the burned wood. Then, to reduce drag in the water, the front and the back of the log were fashioned into a point.
Dugout canoes have been excavated in various locations In northern Europe and are the oldest form of boat ever discovered. Before their arrival there were no other forms of water travel in existence-only swimming and clinging to driftwood.
SEE ALSO: CONTROLLED FIRE, FISHHOOK, CARPENTRY, ROWBOAT, SAIL, RUDDER, STEAMBOAT