Science Fair Project Encyclopedia
A ship is a large, usually decked watercraft. A ship usually has sufficient size to carry its own boats, such as lifeboats, dinghies, or runabouts. A rule of thumb saying (though it doesn't always apply) goes: "a boat can fit on a ship, but a ship can't fit on a boat." Often local law and regulation will define the exact size (or the number of masts) which a boat requires to become a ship. (Note that one refers to submarines as "boats" except for nuclear powered submarines that are classed as ships.) Compare vessel.One alternate, perhaps more modern, definition of a 'ship' is that of any floating craft which carries and transports cargo in an enclosed space between its hulls for the purpose of earning revenue. For example, passenger ships move 'supercargo' (another name for passengers or persons not working on board), and passengers occupy the enclosed space between those ships' hulls. But fishing boats are never considered 'ships' even though fishing boats carry lifeboats and cargo (the catch of the day). However, the space between hulls on fishing boats is unenclosed, and those hulls are usually raised to double as barriers preventing passengers from falling overboard. Ferries are never referred to as 'ships' either. Though ferries float on an enclosed space (a barge usually), that space is left vacant to any sort of cargo.
Some types of ships and boats
- Aircraft carrier
- Auto carrier
- Bulk carrier
- Cable Layer
- Cargo ship
- Commerce raider
- Container ship
- Cruise ship
- Diving support vessel
- Guided missile cruiser
- Minesweeper* and Minehunter
- Ocean liner
- Reefer (refrigerated ship)
- Research vessel
- RO-RO ship (roll on, roll off)
- Sailing ship
Some historical types of ships and boats
- Blockade runner
- East Indiaman
- Liberty ship
- Man of war
- Paddle steamer
- Ship of the line
- Torpedo boat
- Tramp steamer
- Victory ship
One can measure ships in terms of overall length, length along the waterline, beam (breadth) and tonnage.
A number of different tonnage definitions exist, the majority of which measures volume rather than displacement. Displacement most frequently applies to naval vessels and equals the actual weight of a ship under specific conditions. "Light ship" tonnage measures the actual weight of the ship with no fuel, no persons, no cargo, no water on board, just as it first entered the water. The term "displacement" occurs due to the basic physical law, discovered by Archimedes, that the weight of a floating object equates exactly to that of the weight of the water that would otherwise occupy the "hole in the water" displaced by the ship.
In Britain, up until the end of the 19th century, shipowners could load their vessels until their decks were almost awash, resulting in a dangerously unstable condition. Additionally, anyone who signed onto such a ship for a voyage and, upon realizing the danger, chose to leave the ship, could end up in jail.
Samuel Plimsoll, a member of Parliament, realized the problem and engaged some engineers to derive a fairly simple formula to determine the position of a line on the side of any specific ship's hull which, when it reached the surface of the water during loading of cargo, meant the ship had reached its maximum safe loading level. To this day, that mark, called the "Plimsoll Mark", exists on ships' sides, and consists of a circle with a horizontal line through the center. Because different types of water, (summer, fresh, tropical fresh, winter north Atlantic) have different densities, subsequent regulations required painting a group of lines forward of the Plimsoll Mark to indicate the safe depth (or freeboard above the surface) to which a specific ship could load in water of various densities. Hence the "ladder" of lines seen forward of the Plimsoll Mark to this day.
People counting or grouping disparate types of ships may refer to the individual vessels as bottoms. Groups of sailing ships could comprise, say, a fleet of 40 sail. Groups of submarines (particularly German U-boats in the 1940s) may hunt in packs (derived from "wolf packs").
Ships, particulalry sailing ships, involve a rich and varied vocabulary of many technical terms. Many of the following terms link to more detailed discussions of nautical jargon.
- Amidships - the middle section of a ship.
- Bow - the front of a ship. Compare prow .
- Stern - the rear of the ship -- also known in a directional sense as aft
- Starboard - the side of the ship which lies to the right when the observer faces forward.
- Port - the side of the ship which lies to the left when the observer faces forward. (A mnemonic to distinguish port and starboard notes that left and port both have four letters.)
- Bridge - a navigational command centre
- Bulkheads - internal "walls" in a ship. Many bulkheads have a structural function as well as dividing spaces. They serve to maintain stability, to prevent water from flooding the entire ship in the event of a breach of the hull, and to contain fire. Many bulkheads feature watertight doors which, in the case of certain types of ships, the crew may close remotely.
- Cabin - an enclosed room on a deck
- Capstan - pulley-oriented mechanism
- Decks - the "floor"s and also different levels of a ship.
- Deck Head - The "ceilings" inside a ship. Sometimes panelled over to hide the pipework.
- Figurehead - symbolic image adorning the bow of a traditional sailing ship
- Forecastle - an upper forward deck; or sailors' living quarters.
- Galley - the kitchen of the ship
- Gunwhale - the surrounding "wall" at the top of the hull.
- Hold - the lower part of the interior of a ship's hull, especially when considered as storage space for cargo.
- Hull - the shell or framework of the basic flotation-oriented part of a ship
- Keel - the central structural basis of the hull
- Mast - a pole designed for the suspension of one or more sails.
- Prow - alternative term for [bow]
- Scupper - a drainage opening
- Windlass - hydraulic winch mechanism used to raise and lower the ship's cable, and to heave in on hawsers.
See also: Glossary of nautical terms
Before mechanisation, merchant ships always used sail, but as long as naval warfare depended on ships closing to ram or to fight hand-to-hand, galleys dominated in marine conflicts because of their maneuverability and speed. The Greek navies that fought in the Peloponnesian War used triremes, as did the Romans contesting the Battle of Actium. The use of large numbers of cannon from the 16th century meant that maneuverability took second place to broadside weight; this led to the dominance of the sail-powered warship.
The development of the steamship became a complex process, the first commercial success accruing to Robert Fulton's North River Steamboat (often called the "Clermont ") in the USA in 1807, followed in Europe by the 45-foot PS Comet of 1812. Steam propulsion progressed considerably over the rest of the 19th century. Notable developments included the condenser, which reduced the requirement for fresh water, and the multiple expansion engine, which improved efficiency. The paddle wheel gave way to the more powerful screw propeller. Further efficiencies resulted from the development of the marine steam turbine by Sir Charles Parsons, who demonstrated it on the 100-foot Turbinia at the Spithead Naval Review in 1897. This facilitated a generation of high-speed liners in the first half of the 20th century.
The marine diesel engine first came into use around 1912: either the Vulcanus or the Selandia (depending upon who you talk to) first deployed it. It soon offered even greater efficiency than the steam turbine but for many years had an inferior power-to-space ratio. About this period too, oil came into more general use and began to replace coal as the fuel of choice.
Most ships built since around 1960 have used diesel power or motors; one exception, Queen Elizabeth 2 of 1968, started with steam turbines but subsequently converted to diesel as a cost-saving measure.
A few ships have used nuclear reactors, but this form of propulsion has caused concerns about safety and has only become common in large aircraft carriers and in submarines, where the ability to run submerged for long periods has obvious benefits.
Ships in the Bible
The Phoenicians made use of ships for foreign commerce from early in their history (Gen. 49:13). Moses (Deut. 28:68) and Job (9:26) make reference to them, and Balaam speaks of the "ships of Chittim" (Num. 24:24). Solomon constructed a navy at Ezion-geber by the assistance of Hiram's sailors (1 Kings 9:26-28; 2 Chr. 8:18). Afterwards, Jehoshaphat sought to provide himself with a navy at the same port, but his vessels apparently suffered shipwreck before they set sail (1 Kings 22:48, 49; 2 Chr. 20:35-37).
The Book of Jonah depicts a merchant shipping network and some of its crew dynamics.
- concrete ship
- dynamic positioning
- ghost ship
- hospital ship
- Icing (shipping)
- international law
- International Maritime Organization
- maritime law
- ship model
- naval ship
- ship model basin
- ship transport
- List of famous ships
- List of civilian nuclear ships
- List of fictional ships
- Anatomy of the Ship series
- For a list of the prefixes used with ship names (HMS, USS, &c.) see ship prefix.
- I must go down to the sea again, to the lonely sea and the sky,
- And all I ask is a tall ship, and a star to steer her by...
- -John Masefield
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