A ship is a large vessel that floats on water. Ships are generally distinguished from boats based on size and cargo or passenger capacity. In traditional terms, ships were considered to be vessels which had at least one continuous water-tight deck extending from bow to stern. However, some modern designs for ships, and boats, have made that particular definition less accurate. Ships may be found on lakes, seas, and rivers and they allow for a variety of activities, such as the transport of people or goods, fishing, entertainment, public safety, and warfare.
Ships and boats have developed alongside mankind. In major wars, and in day to day life, they have become an integral part of modern commercial and military systems. Fishing boats are used by millions of fishermen throughout the world. Military forces operate highly sophisticated vessels to transport and support forces ashore. Commercial vessels, nearly 35,000 in number, carried 7.4 billion tons of cargo in 2007.[1]
These vessels were also key in history's great explorations and scientific and technological development. Navigators such as Zheng He spread such inventions as the compass and gunpowder. Ships have been used for such purposes as colonization and the slave trade, and have served scientific, cultural, and humanitarian needs.
As Thor Heyerdahl demonstrated with his tiny craft the Kon-Tiki, it is possible to navigate long distances upon a simple log raft. From Mesolithic canoes to today's powerful nuclear-powered aircraft carriers, ships tell the history of human technological development.
Types of ships
Ships are difficult to classify, mainly because there are so many criteria to base classification on. One classification is based on propulsion; with ships categorised as either a sailing ship or a motorship. Sailing ships are ships which are propelled solely by means of sails. Motorships are ships which are propelled by mechanical means to propel itself. Motorships include ships that propel itself through the use of both sail and mechanical means.Other classification systems exist that use criteria such as:
- The number of hulls, giving categories like monohull, catamaran, trimaran.
- The shape and size, giving categories like dinghy, keelboat, and icebreaker.
- The building materials used, giving steel, aluminum, wood, fiberglass, and plastic.
- The type of propulsion system used, giving human-propelled, mechanical, and sails.
- The epoch in which the vessel was used, triremes of Ancient Greece, man' o' wars, eighteenth century.
- The geographic origin of the vessel, many vessels are associated with a particular region, such as the pinnace of Northern Europe, the gondolas of Venice, and the junks of China.
- The manufacturer, series, or class.
oats, pleasure craft and competitive boats. In this section, ships are classified using the first four of those categories, and adding a section for lake and river boats, and one for vessels which fall outside these categories.
Commercial vessels
Commercial vessels or merchant ships can be divided into three broad categories: cargo ships, passenger ships, and special-purpose ships.[36] Cargo ships transport dry a
nd liquid cargo. Dry cargo can be transported in bulk by bulk carriers, packed directly onto a general cargo ship in break-bulk, packed in intermodal containers as aboard a container ship, or driven aboard as in roll-on roll-off ships. Liquid cargo is generally carried in bulk aboard tankers, such as oil tankers, chemical tankers and LNG tankers. Passenger ships range in size from small river ferries to giant cruise ships. Thi
s type of vessel includes ferries, which move passengers and vehicles on short trips; ocean
liners, which carry passengers on one-way trips; and cruise ships, which typically transport passengers on round-trip voyages promoting leisure activities onboard and in the ports they visit.
Special-purpose vessels are not used for transport but are designed to perform other specific tasks. Examples include tugboats, pilot boats, rescue boats, cable ships, research vessels, survey vessels, and ice breakers.
Most commercial vessels have full hull-forms to maximize cargo capacity.[citation needed] Hulls are usually made of steel, although aluminum can be used on faster craft, and fiberglass on the smallest service vessels.[citation needed] Commercial vessels generally have a crew headed by a captain, with deck officers and marine engineers on larger vessels. Special-purpose vessels often have specialized crew if necessary, for example scientists aboard research vessels. Commercial vessels are typically powered by a single propeller driven by a diesel engine.[citation needed] Vessels which operate at the higher end of the speed spectrum may use pump-jet engines or sometimes gas turbine engines.
Here are many types of naval vessels currently and through history. Modern naval vessels can be broken down into three categories: warships, submarines, and support and auxiliary vessels.
Modern warships are generally divided into seven main categories, which are: aircraft carriers, cruisers, destroyers, frigates, corvettes, submarines and amphibious assault ships. Battleships encompass an eighth category, but are not incurrent service with any navy in the world.
Most military submarines are either attack submarines or ballistic missile submarines. Until World War II , the primary role of the diesel/electric submarine was anti-ship warfare, inserting and removing covert agents and military forces, and intelligence-gathering. With the development of the homing torpedo, better sonar systems, and nuclear propulsion, submarines also became able to effectively hunt each other. The development of submarine-launched nuclear missiles and submarine-launched cruise missil
ility to attack both land and sea targets with a variety of weapons ranging from cluster bombs to nuclear weapons.
Most navies also include many types of support and auxiliary vessels, such as minesweepers, patrol boats, offshore patrol vessels, replenishment ships, and hospital ships which are designated medical treatment facilities.[38]
Combat vessels like cruisers and destroyers usually have fine hull
s to maximize speed and maneuverability.[39] They also usually have advanced electronics and communication systems, as well as weapons.
Fishing vessels
Fishing vessels are a subset of commercial vessels, but generally small in size and often subject to different regulations and classification. They can be categorized by several criteria: architecture, the type of fish they catch, the fishing method used, geographical origin, and technical features such as rigging. As of 2004, the world's fishing fleet consisted of some 4 million vessels.[32] Of these, 1.3 million were decked vessels with enclosed areas and the rest were open vessels.[32] Most decked vessels were mechanized, but two-thirds of the open vessels were traditional craft propelled by sails and oars.[32] More than 60% of all existing large fishing vessels[40] were built in Japan, Peru, the Russian Federation, Spain or the United States of America. [41]Fishing boats are generally small, often little more than 30 metres (98 ft) but
up to 100 metres (330 ft) for a large tuna or whaling ship. Aboard a fish processing vessel, the catch can be made ready for market and sold more quickly once the ship makes port. Special purpose vessels have special gear. For example, trawlers have winches and arms, stern-trawlers have a rear ramp, and tuna seiners have skiffs.In 2004, 85.8 million metric tons of fish were caught in the marine capture fishery.[42] Anchoveta represented the largest single catch at 10.7 million metric tons.[42] That year, the top ten marine capture species also included Alaska pollock, Blue whiting, Skipjack tuna, Atlantic herring, Chub mackerel, Japanese anchovy, Chilean jack mackerel, Largeh
ead hairtail, and Yellowfin tuna.[42] Other species including salmon, shrimp, lobster, clams, squid and crab, are also commercially fished.
Modern commercial fishermen use many methods. One is fishing by nets, such as purse seine, beach seine, lift nets, gillnets, or entangling nets. Another is trawling, including bottom trawl. Hooks and lines are used in methods like long-line fishing and hand-line fishing). Another method is the use of fishing trap.
Inland and coastal boats
Many types of boats and ships are designed for inland and coastal waterways. These are the vessels that trade upon the lakes, rivers and canals.Barges are a prime example of inland vessels. Flat-bottomed boats built to transport heavy goods, most barges are not self-propelled and need to be moved by tugboats towing or towboats pushing them. Barges towed along canals by draft animals on an adjacent towpath contended with the railway in the early industrial revolution but were out competed in the carriage of high value items because of the higher speed, falling costs, and route flexibility of rail transport.
Riverboats and inland ferries are specially designed to carry passengers, cargo, or both in the challenging river environment. Rivers present special hazards to vessels. They usually have varying water flows that alternately lead to high speed water flows or protruding rock hazards. Changing siltation patterns may cause the sudden appearance of shoal waters, and often floating or sunken logs and trees (called snags) can endanger the hulls and propulsion of riverboats. Riverboats are generally of shallow draft, being broad of beam and rather square in plan, with a low freeboard and high topsides. Riverboats can survive with this type of configuration as they do not have to withstand the high winds or large waves that are seen on large lakes, seas, or oceans.
Lake freighters, also called lakers, are cargo vessels that ply the Great Lakes. The most well-known is the SS Edmund Fitzgerald, the latest major vessel to be wrecked on the Lakes. These vessels are traditionally called boats, not ships. Visiting ocean-going vessels are called "salties." Because of their additional beam, very large salties are never seen inland of the Saint Lawrence Seaway. Because the largest of the Soo Locks is larger than any Seaway lock, salties that can pass through the Seaway may travel anywhere in the Great Lakes. Because of their deeper draft, salties may accept partial loads on the Great Lakes, "topping off" when they have exited the Seaway. Similarly, the largest lakers are confined to the Upper Lakes (Superior, Michigan, Huron, Erie) because they are too large to use the Seaway locks, beginning at the Welland Canal that bypasses the Niagara River.
Since the freshwater lakes are less corrosive to ships than the salt water of the oceans, lakers tend to last much longer than ocean freighters. Lakers older than 50 years are not unusual, and as of 2005, all were over 20 years of age.[43]
The St. Mary's Challenger, built in 1906 as the William P Snyder, is the oldest laker still working on the Lakes. Similarly, the E.M. Ford, built in 1898 as the Presque Isle, was sailing the lakes 98 years later in 1996. As of 2007 the Ford was still afloat as a stationary transfer vessel at a riverside cement silo in Saginaw, Michigan.
