What is a ship?
A big piece of metal that floats miraculously on the surface of the water, and usually used to transport people and/or cargo. It is type of boat that floats on water. It is water borne transportation vehicle.
What does a ship need?
A watertight body complying with Archimedes’s flotation law to float on water. Means to move it (Propel over the water). To justify expenses of building and operating, some income from the venture. And of course, trained people to maintain and run it.
How did shipping start?
Human beings are around for about 1 million years. It is believed that water crafts are around for about 50000 years. There is an evidence of a boat about 10000 years ago in a museum.
Humans were nomadic population and moved around for food. Over the centuries, they learned to form small groups and hunt. While hunting they discovered fish in water. Well you know how tasty is the fish. How to catch it? As a matter of fact, almost all animals can swim without training. It appears that Humans had lost swimming skill during evolution. Humans needed a method to float on water to catch fish or to cross waterways. They observed floating stuff like dead animals, wood, floating plants etc. They discovered that trapped air gave buoyancy. Next came animal hide “Balloons”. Then they found ways to tie up reed to make floating device. Probably large number of population died during experimentation. Of course, humans also learned swimming. However, Swimming was tiring and persons could not carry much of load. Currents decided their direction of movement. Over subsequent centuries, humans realized wind power. Earlier sails were made up of branches of trees and animal hides. Later on some sort of fabric was used. Somewhere during these formative years, humans started using floating devices for traveling and carrying cargoes. Earlier crafts were small boats and rafts.
Human beings were nomadic and settled down near sources of fresh water like river banks and lakes. Their requirements were low, so small crafts served the purpose. Normally rivers and lakes do not get bad weather and big waves. Therefore initial crafts were not strong enough for oceans.
Around 4000-3000 CE, there was lot of migration and also many empires were formed. This development demanded ocean travels needing stronger ships. These ships could ply in Mediterranean seas carrying passengers and cargoes. Similar ships started plying in Asia and other parts of the world. These ships were made up of wood that restricted their sizes to about 500 – 1000 TONS ( 1 ton= 100 cu ft). It was difficult to make longer ships due to lack of technology. Ship’s became larger only when metal ships were introduced.
The ‘Age of Discovery,’ between the mid 1400s and early 1900s was the time when humans explored Earth creating maps and charts and bringing specimens back to their home ports. This was a time of development of ocean-going ships and adventurous men. Most of this exploration came out of European countries (Spain, Portugal, France, Scandinavia, Italy, Germany). Some of the landmark explorers in the marine science area are Christopher Columbus, Ferdinand Magellan, Captain James Cook and Charles Darwin. Columbus is credited with the discovery of North America in 1492, however the Vikings had already been there but this knowledge had not been passed on to the Europeans. Magellan was the first person in charge of an expedition to go completely around Earth in 1519. Colonization process started during these periods. Colonization also created lot of trade and trade needs transportation vehicles like ships.
These ships were sailing ships with no fixed schedule that created lot of anxiety. During 18th century, people started working on steam engines for the ship. This needed more than 100 years of research to have a practically working ship with steam propulsion. First seagoing iron ships appeared in mid 19th century powered by steam engines. They were propelled by “Side Paddles”.
Later on Paddles changed into modern day propellers. In spite of having knowledge of Archimedes’ principle for over 2000 years, humans did not venture into Iron Ships till around 1787 (Wilkinson’s iron boat).
By 1900 AD we had steam and metal technologies to construct bigger ships for ever growing trade demands.
In 1840, Cunard Line’s RMS Britannia began its first regular passenger and cargo service by a steamship, sailing from Liverpool to Boston
In 1847, the SS Great Britain became the first iron-hulled screw-driven ship to cross the Atlantic. More efficient propellers began to replace the paddle wheels used by earlier ocean liners.
The size of ocean liners increased from 1880 to meet the needs of immigration to the United States and Australia.
In 1910, White Star Line launched RMS Olympic, the first of a trio of 45,000 plus gross ton liners, along with RMS Titanic and HMHS Britannic.
In 1929, the German ships SS Bremen and SS Europa broke the speed record set by Mauretania (20 years earlier) with an average speed of almost 28 knots (52 km/h; 32 mph). The ships used bulbous bows and steam turbines to reach these high speeds while maintaining economical operating costs.
The key innovation that made ocean-going steamers viable was the change from the paddle-wheel to the screw-propeller as the mechanism of propulsion.
Pre-aircraft days, business was good for passenger ships and all innovations were tried on them. Later on they were passed on to Cargo ships.
Diesel engines made entry around 1912 and took some time to settle down by 1970. They had some issues with maximum output due to metallurgical problems. Today we can have engines with 100,000 BHP.
Stability of European empires allowed shipping to settle down and provide scheduled services.
Stability also provided growth of Industries and trade. British empire became seat of maritime power and trade. Birth of Telegraph in 19th century and laying of submarine cable helped further development of shipping. Barges came in lime light in colonies as Port development lagged behind development in ship’s sizes.
Earlier ships were combination of Passengers, Navy and Cargo.
First division was separation of Navy who got specialized role and ships.
Then came specially designed General cargo ships with limited passenger capacity. General cargo ships lasted over a long time as demand was for smaller parcel sizes and larger distribution areas.
These ships could carry Dry cargoes, Bulk cargoes, Reefer cargoes as well as Liquid cargoes. However during 1960’s demand started for Bigger parcel sizes and specialized ships. In 1960’s world started reacting to specialized ships like Bulk carriers, Tankers, Reefer ships and Container ships. Deadweight capacities of ship’s crossed 100000 t by 1962. Post 1973 war closure of Suez canal saw birth of Tankers of over 550000 t capacity (Over 458 m long, 69 m wide, draft 24 m). Bulk carriers are not behind, today biggest ships are 360m long, 65 m wide with dead weight of 400000 t. Container ships are 400 m long, 60 m wide with capacity of over 19000 TEUs. Similarly other ships have become larger.
A typical cargo ship is divided into parts.
1. Cargo carrying area: This varies according to cargo inside a box shaped volume, consisting of ship sides, ship’s bottom and Deck. This area may have cargo loading/discharging gear.
2. Propulsion machinery area: This is normally aft keeping length of propeller shaft short. It is always below deck.
3. Crew accommodation and Navigation control area: Varies according to what is left over area on deck. It may be forward, aft or in the middle. Navigation bridge is the highest position for better view.
4. Bow and stern areas (Underwater and Over water) designed for smooth aerodynamic and hydrodynamic factors: They have similar design on all ships to keep resistance to wind and water as low as possible. This decides fuel consumption.
So our ship is a box, streamlined for smooth passage through the water and pushed by underwater propeller.
Let us prepare ourselves for next chapter “Types of Ships”.
What is CARGO? It is Commodity that is transported on a vehicle (Ship). It may be anything in transportable form. Typical examples are
Mobile phones / Computers / Electronic goods – Transported in boxes and cases.
Food grain : Bulk (Loose) or in bags
Frozen goods : In temperature controlled compartments or boxes
Liquids like edible oils, Fruit juices, petroleum products etc: In bulk or packaged formative
Cattle: In groups with usual facilities like shelter, food and watertight
Cars and vehicles: Parking space required
PEOPLE: Yes people have to considered as cargo for designing a ship, need HOTEL arrangement or Bus/Train like arrangement.
So cargo part has to be defined suitably for carriage of cargo in safe manner. Obviously loading/discharging arrangements must be suitable so that there is no damage to the cargo. All ships are designed specifically for carriage of cargo and differ from each other for different cargoes.
What about people who will be sailing with the ship? They need to be protected from weather, need food, water, work tools, entertainment and communication. So we need to have Cabins (Rooms), common areas(Halls, eating areas, laundry, bathrooms, toilets, game room and recreation rooms), That is achieved by just making a building on deck something like a small hotel with all facilities. This is supported by restaurant like feature of Galley (Kitchen), cold stores, dry provision rooms etc. They need electricity, hot / cold water, temperature controlled climate and communication equipment. Realizing we are at sea alone, we need efficient backup systems like you have inverters at home.
Now we need to address “Propulsion”. We are propelled by a propeller (Fan) which runs underwater , follows Newton’s 3rd law and gives us velocity. Propelling machinery along with other equipment needed for other activities need large space. Idea is to use minimum space so that we can have larger cargo space. Normally Machinery space is placed aft (End of ship).
Navigation bridge is a NAVIGATOR’S (Drivers) location. It needs clear visibility all over the horizon. It is the highest (Tallest) location of the accommodation.
Now we have building blocks ready. We need to follow Archimedes’s law to make ship float. We have people sailing on ship so we need adequate SAFETY for flotation. Especially we don’t want ship to sink after a minor accidental damage. This is called reserved buoyancy and is controlled by the law. Ballast tanks and sub divisions (Partitioning of ship’s volume) are used for this purpose. We need to make ship waterproof with smooth hull that cuts through the water smoothly. Part of the ship is above the water and part is below the water. So we need Aerodynamic shape above water and Hydrodynamic shape below water.
Various openings in the HULL (Body of the ship) and deck are made watertight by various means.
While considering above factors, attention is paid to weather conditions at sea. Sea can be very rough and ship needs to be strong to withstand storms faced at sea. Various stresses are considered while designing a ship. Fire prevention precautions are addressed separately.
Let us see what Captain DOGO has to say to Cadet DOZO.
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