Have you ever wondered, what is a ship? What makes a ship different than a boat? Well, if you have ever wondered about these or other ship related questions, you may want to keep reading. We will go over several areas in this article, including what they are, they history and the various types of ships out there.
What are Ships?
Ships are large vessels which are designed for traveling around the world on oceans, and other waterways that are very deep. They usually carry products or passengers with a specific goal. Ships can be used for fishing, transporting people or goods, research or defense purposes to name a few. In history, “ship” was a term for sailing vessels that had a minimum of three square-rigged masts with a full bowsprit. Generally, there are a few ways to distinguish ships from a boat, including the size, shape, and load capacity.
Although there is no universally accepted difference between boats and ships, a ship is typically much larger than a boat. In addition, ships are designed to stay at sea for much longer periods compared to a boat. However, an Indian case law legally defines a ship as a vessel carrying goods over the sea. When it comes to comparing size, one common example is a ship can carry a boat, but a boat cannot carry a ship.
The U.S Navy uses rule of thumb that boats heel to the inside of sharp turns, while ships heel to the outside due to their center of mass and buoyancy. Meanwhile, a maritime law in British 19th century defines ships and boats as ‘vessels’ in a single legal category, where rafts and open boats are not defined as a vessel.
Ships in History
Vessels are recorded way back, with the first known vessel being estimated to be more than 10,000 years old. However, it cannot technically be considered a ship. Navigators first used woven fabrics and animal skin for sails, connected to an upright pole in the boat. This enabled ships to get more range and enabled explorers to cover more ground, which provide the resources for the settlement of Oceania around 3,000 years ago.
The Ancient Egyptians in 3000 BC understood methods for assembling wood planks to create a hull. The planks were held together with woven straps, with grass or reeds between planks to assist in creating seams and sealing the hull. Agatharchides was a geographer and Greek historian that documented early Egyptian ship-farming. The initial referencing to a ship by name, is documented in 2613 BC, being the ancient cedar wood ship of Sneferu “Praise of the Two Lands”.
One vessel made by ancient Egyptians is the Khufu ship, which measured 143 ft in length, constructed around 2500 BC and discovered in 1954, intact. Evidence exists that ships may have sailed between Sri Lanka and Nubia to trade goods
Ships developed towers on the stern and bow by the end of the 14th century, such as the carrack. The stability was decreased by the towers, leading to the Portuguese designing the caravel in the 15th century, basing it on Arabic qaib that sailed closer and became more common. In time, towers were slowly replaced with stern castle and forecastle on the Santa Maria (Christopher Columbus), which lead to increased freeboard, free port and associated artillery.
The 16th century used freeing ports on galleons. It was not until 1498 that new trade routes was established, accelerating European exploration and allowing access to the Indian Ocean from the Atlantic. Thus, resulting in the route to Australia (1606), New Zealand (1642).
In 2002, there were an operating 1,240 warships worldwide, excluding smaller vessels like patrol boats. In 2004, an estimated to be 4 million fishing vessels, and in 2007 a fleet of 34,882 commercial vessels.
Various Types of Ships
According to Paulet and Presles, ships are built with naval architectural principles that require similar structural components, while classification comes from functions. The following are accepted by naval architects:
The following is more on some common types of ships.
Freshwater
This type of ship is constructed for freshwater shipping, such as on canals, rivers and lakes. They are built to adapt with the depth of the waterway of use, such as the Mississippi, Danube, Amazon river and others.
Great Lakes
This is a cargo ship referred to as a lake freighter build for the great lakes. Traditionally, these are boats and not ships. Visiting ocean vessels are referred to as ‘salties’, but large salties are unable to be inland. However, salties small enough to fit in the Seaway are able to travel anywhere on the great lakes.
Seagoing Commercial Vessels
Merchant ships or commercial vessels all into four categories: cargo, fishing, passenger, and special purpose. Meanwhile, UNCTAD maritime transport puts them into the following categories: oil tanker, bulk carrier, container ships, general cargo, and “other”.
Typically, modern commercial vessels are powered with a propeller running by diesel engine, or less common a gas turbine. However, until middle of the 19th century, they were mostly square sail rigged. Meanwhile, pump-jet engines are used on the fastest vessels.
Fishing vessels can rage between more common 98ft to 330ft whaling ships. They are designed with special gear, such as trawlers. This gear allows for various methods of fishing, from net fishing to trap fishing.
Cargo ships are designed to transport liquid or dry goods. Bulk carriers can transport dry cargo, whereas liquid cargo is often carried in tankers. Oil tankers for example, can include finished oil product or crude oil, and chemical tankers could transport vegetable oils.
A passenger ship can range greatly in size, from small river farriers, to cruise ships. Ferries transport people short distances, while ocean liners transport a large number of people between longer distances. Cruise ships transport passengers on a voyage for pleasure, often stopping at various ports with many activities on board.
Special Purpose Vessels
There are various special purpose vessels, or example a weather ship was one used for a platform in the ocean to obtain upper air and surface meteorological data for marine weather forecasts. The observations of the surface were taken on an hourly basis, where four daily radiosondes were released. Weather ships could aid in a search and rescue operation, and for translantic flights. They were useful during WWII, and were commonly at sea for several weeks with 10 day returns to port.
Naval Vessels
These are designed and used by the navy. Various types have been made, with three main categories of naval vessels being: surface warships, support and auxiliary, and submarine.
There are seven modern warship categories: aircraft carrier, cruiser, destroyer, corvettes, frigates, amphibious assault ship, and submarine. However, the definition of corvettes, cruisers, destroyers and frigates are not major. The same vessel could be defined in different ways between navies.
The majority of military submarines are ballistic missile submarines or attack submarines. They use sonar systems and require functions such as homing torpedo, and nuclear propulsion.
Ship Architecture
There are several parts to a ship, including:
The Hull
To enable a ship to float, it has to disburse weight to be less of the water, this is allowed by a ship’s hull. There are various hull designs, from logs to more advanced sailboat hulls. A vessel may have a single hull (monohull), two hulls (catamarans), or three hulls (trimarans). It is rare, but some have more than three hulls as experiments.
The front of the hull is the bow. The hull bottom is the keel, which extends the ships length. The rear is the stern, with many having flat backs called transom. Common appendages on hulls include rudders (steering), propellers (propulsion), and stabilizers.
Propulsion System
Ships go in three categories based on the propulsion system: human propulsion, mechanical propulsion, and sailing.
Human propulsion includes rowing, such as on galleys. Sailing propulsion often requires a hoisted sail, controlled with ropes and was a dominant type of propulsion until the 19th century. Meanwhile, mechanical propulsion uses a wave propulsion fins or impellers.
Steering System
If a ship has independent propulsion system on each side, a steering system may not be required. However, in many designs where sail or engines propel the ship, a steering system is needed. The more common system is the use of a rudder, which is submerged at the rear of the hull and creates a lateral force to move the ship.
Holds, Superstructure and Compartments
There are often several decks and compartments on larger ships. Separate heads and berthing’s are located on sailboats longer than 25 feet, while a fishing vessel tends to have one or more cargo holds. It is common for larger ships to have a galley, engine room, and other work related compartments. Tanks store the engine oil, fuel, and fresh water. Meanwhile, ballast tanks are used for changing the ship’s trim and stability.
Finally, superstructures are located above the main deck. These tend to be low on sailboats, while modern cargo ships usually have them towards the stern of the ship. Meanwhile, warships and passenger ships often extend the superstructure forward.
