The Ship

Why Ships ??

More than two thirds of the Earth’s surface is covered by water and naturally water transportation is the oldest mode of transportation.  Ever since man designed crafts to float on seas, goods have been carried between ports worldwide. The demand for ships is derived from the demand for the goods they carry.

Ships have been used for trade for thousands of years, but the present shipping business is the result of technology developments and practice established over the last 150 years. The invention of ‘iron’ and steam engine did wonders to shipping trade and caused eventual demise of wooden sailing ships. However, today the ships are powered primarily by diesel engines.

The ship

The ship is obviously the Fundamental tool for all commercially related shipping activities. There are two main parts to a ship – The Hull & the Machinery. Hull is the actual shell of the ship  including the superstructure where as machinery includes not only the engine required to drive it  but also the  generators required for lighting, refrigeration and other auxiliary loads.

Bows , Stern , Amidships, Beam

The front portion of the ship is called the fore end and the extreme forward end is called the bows. The vessel is said to be moving ahead when bows move first.

The rear portion / back end of the ship is termed the after end or stern. When moving stern first, the vessel is said to be astern.

The area between forward and aft portions of the vessel is called amidships. The maximum breadth of the vessel in amidships is called the beam.

The bridge of the vessel is the navigating centre. On modern ships the navigating bridge, machinery and crew accommodations are situated aft.

Bow & side thrusters, stabilizers

Modern vessels have transverse propulsion units in the bows known as bow thrusters. Many vessels have side thrusters fitted at the stern. Their purpose is to provide greater manoeuvrability in confined waters like ports and to reduce or eliminate usage of tugs.

Stabilizers are something similar to the fins of a ship, fitted in pairs deep below the water line. Their purpose is to reduce rolling of the vessel in heavy seas.

Types of Ships

Cargo ships are designed for carrying particular commodity or group of commodities. The type of vessel deployed on a trade route is determined basically by the traffic carried.

The Bulk Carrier

Dry bulkers are the simplest ship in terms of construction and it generally carries homogenous cargoes in bulk like coal , iron ore, grains etc. Depending upon the size of the vessel they can be termed as

1. The Panamax  (50,000 – 79,999 dwt)- The largest size of ships that can be passed through the Panama Canal .
2. The Capesize  (80,000-170,000 dwt) – too large for the Suez or Panama Canal .
3. The Handymax (35,000 – 49,999 dwt) – Popular for smaller shipments of bulk cargo – ideal for smaller ports with limited facility

4. The Handysize (20,000 – 34,999 dwt) – Ideal for ports of limited drafts and berth length. Suitable for grain Shipments .

 Tankers

These are vessels which carries liquid bulks. Oil tankers are used to transport crude oil from the oil fields to refineries and petroleum and fuel oil from refineries to distribution centres and bunkering ports. Hence tankers have a worldwide network routes.

Depending the size there are a range of oil tankers 

1. ULCC (Ultra Large Crude Carrier 3-500000 dwt)
2. VLCC  (Very Large Crude Carrier 1.5 to 299999 dwt)
3. Suezmax (1.2 to 1.5 lakh dwt, could  transit Suez canal)
4. Aframax (80,000 to 119999 dwt – used in clean product (aviation, motor spirit) trading
5. Panamax (50,000 to 80,000 dwt , presumed to transit thru’ Panama Canal)

Container Ships

These are becoming increasingly predominant in many trade routes and they can carry a wide range of cargo in containers.  Container ships are ‘cellular’, which means that the vessel holds are fitted with vertical metal guides called ”cell guides” into which containers can slide and thus they are secured from any movement. Though below deck the containers are secured by cell guides, on hatch covers they must be lashed in order to prevent movement.

Ro-Ro Vessel

These vessels are designed for any type of vehicles. Ro-Ros have been designed with ramps in convenient position (stern,bows,side). Ro-Ro ships designed for carriage of new cars are called  Pure Car Carriers. The vessels designed to carry cars and trucks are called PCTS – Pure Care & Truck Carriers. Ro-Ros commonly have their capacity    measured in LANE METRS .  This measure gives an indication of     total length available for vehicles of     given width.

Combi Carrier

Combi carriers are unitized type of cargo carriers , combining Container and vehicular shipments, including   ro-ro . It has a versatile cargo mixture , can carry odd shaped cargo along with unitised cargo. These ships are suitable for a wide range of ports and hence in operation worldwide. A number of Combi carriers are introduced now

-To improve the ship turn-round time

- to improve the versatility of sea transport

- To minimize the operating cost

 General Cargo Ships

They are also called conventional vessels used for the carriage of diverse form of dry cargo. These vessels are almost disappeared due to Containerization . Most of the conventional vessels are Tween Deckers , ie, Ships with 2 or more decks . (“Tween” derives from “Between” , ie, decks between the uppermost deck and the ship’s bottom). This facility adds to the variety of cargo the vessel can carry.

Gas Carriers

The movement of gas, both Natural and Petroleum, is now a major trade in shipping industry. Both type of gases are carried in liquid form and of course both products need purpose built ships.

LPG carriers normally have cylindrical tanks made of aluminum alloys and are self supporting and free standing.LPG (Butane & Propane) can be kept in liquid form under high pressure at a low temperature. Modern LPG carriers are fitted with refrigeration equipment in order to maintain the temperature of the cargo. This helps to liquefy the vaporization during voyage or at discharge point.  

LNG has to be carried under very low temperature (-104 deg cen to – 163 deg cent) and at atmospheric pressure. The vessel has insulated spherical tanks protruding high above the ship’s deck to carry cargo. They are made of aluminium alloy , surrounded by insulation and protected by a steel outer shell. Tanks are connected to vessel’s hull but not a part of it.

Refrigerated (Reefer) Ships

Refrigerated ships or reefer ships are designed  to carry fresh produce. Development of reefer ships helped to trade meat resource of Australia & New Zealand. Reefer ships are also designed to carry non-refrigerated cargo too as reefer trade generally is seasonal and one way. These types of vessels are in decline due to development of reefer container trade.

Heavy Lift Ships

This is an emerging trade and is  used for the transportation of  indivisible loads . This is a risk market and generally is spot market  in nature with a reasonable return. Long term contract of such ships are found in oil contractors, fabricators and conversion yards.