SHIP MEASUREMENTS

By -Kevin JosephMBA (Energy Trading)

Tonnage

Tonnage is a measure of the size or cargo carrying capacity of a ship.

“Tonnage" specifically refers to a calculation of the volume or cargo volume of a ship.

Tonnage should not be confused with Displacement which refers to the loaded or empty weight of the vessel itself.

A commonly defined measurement system is important; since a ship’s registration fee, harbour dues, safety and manning rules etc., are based on its gross tonnage, GT, or net tonnage, NT.

There are five kinds of tonnage in use in the shipping business.They are:

Deadweight Cargo, Gross, Net and Displacement

Tonnages

Tonnage measurements :

Dead weight tonnage

It is a measure of how much weight a ship can safely carry.

It is the sum of the weight of cargo, fuel, fresh water, ballast water, provisions, passengers and crew.

Cargo : it is the goods or produce transported for commercial gain by the ship

Gross tonnage (GT) is a function of the volume of all ship's enclosed spaces (from keel to funnel) measured to the outside of the hull framing.

Net tonnage (NT) is based on a calculation of the volume of all cargo spaces of the ship.

It indicates a vessel’s earning space and is a function of the molded volume of all cargo spaces of the ship.

It represents the volume of the ship available for transporting freight or passengers.

Displacement : it is the unit for the total weight of the ship and her contents, equivalent to the weight of water displaced under any particular condition of loading given in terms of the defined weight system i.e metric or long tons

The Panama Canal/Universal Measurement System (PC/UMS) is based on net tonnage, modified for Panama Canal purposes. PC/UMS is based on a mathematical formula to calculate a vessel's total volume; a PC/UMS net ton is equivalent to 100 cubic feet of capacity.[3]

The Suez Canal Net Tonnage (SCNT) is derived with a number of modifications from the former net register tonnage of the Moorsom System and was established by the International Commission of Constantinople in its Protocol of 18 December 1873. It is still in use, as amended by the Rules of Navigation of the Suez Canal Authority, and is registered in the Suez Canal Tonnage Certificate.

Thames measurement tonnage is another volumetric system, generally used for small vessels such as yachts; it uses a formula based on the vessel's length and beam.

Bunker Bunker is simply the name

given to the Fuel that is used to operate ships.

Bunker fuel is technically any type of fuel oil used aboard ships. It gets its name from the containers on ships and in ports that it is stored in; in the days of steam they were coal bunkers but now they are bunker fuel tanks.

The Australian Customs and the Australian Tax Office define a bunker fuel as the fuel that powers the engine of a ship or aircraft. Bunkering Ship =>

Bunker oil is literally the bottom of the barrel; the only things more dense than bunker fuel are carbon black feedstock and bituminous residue.

In the context of shipping, the labeling of bunkers as previously described is rarely used in modern practice.

Deadweight cargo capacity(DWCC) or net capacity is a measure of the deadweight of a ship in terms of the cargo she can transport, excluding fuel, water, crew and everything else that is not part of the ship.

DWCC- it is the most important for the Charterers i.e whose cargo has to be shipped. it gives the weight of the cargo that the vessel can carry.

The more fuel the vessel needs the lower the DWCC. this also depends on the water temperature and water(salt, brackish) in summer vessels have high DWCC

Dead weight all told(DWAT) is a term that states the total amount of weight that a ship may carry before it passes the waterline, including the weight of: cargo, water, crew, fuel, food and anything else that is not part of the ship and is not counted in its' light displacement.

(Dead weight all told) = (Loaded displacement)-(light displacement)

Water line It is the line where

the hull of a ship meets the surface of the water in concept or reality.

It is also used as the international loadline to keep a watch on the loaded cargo.

It indicates the draft of the ship

Lightering Also known as lighterage

Lightering is the process of transferring cargo between vessels of different sizes, usually between a barge and a bulker or oil tanker.

Lightering is undertaken to reduce a vessel's draft in order to enter port facilities which cannot accept very large ocean going vessels. 

Steve Dore The primary role of a

stevedore is the loading and unloading of freight on an off ships while they are in port

Other responsibilities includes- 1-mooring and unmooring

ships 2- cleaning and preparing

container 3-stacking and securing

cargo's 4-adminitravtives process

associated with the transfer of cargo

Stevedore(also known as a dock worker, docker or dock laborer, wharfie) is usually the entry point for individuals seeking a carrier on the docks or within ports

Stevedores can than progress to became a crane operator, foreperson or container terminal manager

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