Measurements of a Ship -Tonnage,LOA,Beam,Draft

  Tonnage Measurement

Ship’s cargo carrying capacity generally describe in ‘tons’, but it does not refer to the weight ton at all. It was originally derived from the word ‘tun’ , referred to the 252-gallon barrel used in the wine trade in olden days. Then the convenient way of estimating a ship’s size was to calculate how many of such barrels she could carry and that figure was used as ship’s “Register Tonnage”

Gross Tonnage & Net Tonnage

 From the above mentioned tradition , the Gross Register Tonnage (GRT) and Net Register Tonnage (NRT) evolved. Though GT & NT (new system, came in force from 1994)are called as "Tonnages' actually they are the cubic measurements based on an international formula for comparing the overall size of ships. GT is used by ports as the basis for levying vessel related expenses like berth hire , pilotage , port dues and NT is used by customs as a basis for calculation for Light House dues (ILH = NRT x Rs8).

GT - The internal cubic measurement of all the enclosed spaces within the ships hull and superstructure.

NT - The GT minus the space which is not used for commercial purpose such as crew accomodation area, engine room etc.

Displacement Tonnage – The actual wt. of a ship, the weight of the body is equal to the weight of water it displaces ( Archimedes Law).

Light Displacement – Actual wt. of the empty ship (without fuel , cargo , stores etc)

Deadweight (dwt) – Difference in tons between the light and loaded displacement. Represents the total weight a ship can carry (cargo + fuel + stores + fresh water etc)

Measurements of ship

Below given are the important dimensions of a ship which determines whether ship can safely enter canals,locks , port approach chanels, berths etc.

Length Over All (LOA) - The length of a a ship from the foremost point on the bow to the mostaft point on the stern.

Beam - The maximum breadth of the ship, which is in the amidships( the area between forward and the aft portion) body.

Draft - The distance between the bottom of the ship (the keel) to the level of water on the ships side (water line)

ü The more cargo the ship loads, greater her draft would be. Every state of the ship’s draft there is a corresponding total dead weight

ü The draft of a port refers to the depth of water available at the port channels / terminal basin

Air Draft - The distance from the waterline to the highest point on the ship's super structure ,usually the top of the mast.

Prospects of Coastal Shipping in India

India is emerging as a modern economy. The Government is committed to ensure that economy grows at 7 to 8 percent per year in a sustained manner over next decade. In order to realise this growth potential, the attention also needs to be given to development and modernisation of our economic infrastructure. To become globally competitive, utmost importance must be given for development of infrastructure in sectors like roads, airports, sea-ports, railways in general and maritime transport in particular.

Economic reforms in India have triggered a high rate of economic growth in the country and this in turn has led to an increase in transport demand. This demand is being met mainly by the rail and road transport systems.

In spite of a 7517 km coastline, dotted by 12 major and 185 minor ports, coastal shipping in India is playing a marginal role only in the transport system. With higher than average traffic growth is projected at several corridors, substantial capacity enhancement will be required over the next 10-15 years. This makes imperative the need to look closely at the potential of the coastal shipping transport systems to ease the pressure on surface transport modes and arrest the continuous damage caused to environment. It is estimated that the nation would save Rs. 15-20 billion through diversion of 5% of cargo from road apart from reduction in pollutants by 6% and savings in fuel .

Coastal Shipping (Short Sea Shipping) refers to the movement of cargo and people over water without crossing a major ocean. In the sea, we have an old medium awaiting revived use. A comprehensive strategic transportation plan, national and intermodal in its scope , is the need of the hour. Coastal shipping could complement, not compete with, trucking and rail and have to play an important role in the growing economy. Our goal should be to reduce the stress on road and rail and also on environment by diverting a sizable percentage of cargo moved by rail and road to coastal shipping. Minor ports, now underused, could enjoy all the benefits of a new economic development. A relatively modest investment in our nation’s coastal sea routes would bring substantial benefits by reducing burden on present transportation system, traffic congestion and pollution.