Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Tonnage shopping experience:
1. Compare - without doubt the biggest advantage that the Tonnage offers shoppers today is the ability to compare thousands of Tonnage at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Tonnage? Wrong! If the Tonnage is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Tonnage then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Tonnage? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Tonnage and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Tonnage wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Tonnage then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Tonnage site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Tonnage, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Tonnage, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
Tonnage is a measure of the size or cargo capacity of a ship. The term derives from the taxation paid on
tuns of wine, and was later used in reference to the weight of a ship's cargo; however, in modern maritime usage, "tonnage" specifically refers to a calculation of the volume or cargo volume of a ship. The term is still sometimes incorrectly used to refer to the weight of a loaded or empty vessel.
Measurement of tonnage can be less than straightforward, not least because it is used to assess fees on commerce
shipping.
Tonnage measurements
Gross Register Tonnage (
GRT) represents the total internal
volume of a vessel, with some exemptions for non-productive spaces such as crew quarters; 1 gross register ton is equal to a volume of 100
cubic foot (2.83
cubic metre). This calculation is complex; a hold can, for instance, be assessed for cereal (accounting for all the air space in the hold) or for bales (exempting the spaces between structural frames). Gross register tonnage was replaced by
gross tonnage in 1994 under the Tonnage Measurement convention of 1969, but is still a widely used term in the industry.
CWP Handbook of Fishery Statistical Standards. Retrieved
May 10,
2006.
International Convention on Tonnage Measurement of Ships, 1969, International Maritime Organisation. Retrieved May 10, 2006.
Net Register Tonnage (
NRT) is the volume of cargo the vessel can carry; ie. the Gross Register Tonnage less the volume of spaces that will not hold
cargo (e.g.
engine compartment,
Ship's wheel station,
crew spaces, etc., again with differences depending on which
port or
country is doing the calculations). It represents the volume of the ship available for transporting freight or
passengers. It was replaced by
net tonnage in 1994, under the Tonnage Measurement convention of 1969.
Gross Tonnage (
GT) refers to the volume of all ship's enclosed spaces (from
keel to funnel) measured to the outside of the hull framing. It is always larger than
gross register tonnage, though by how much depends on the vessel design. It was a measurement of the enclosed spaces within a ship expressed in "tons" – a unit which was actually equivalent to 100 cubic feet.
Tonnage measurements are now governed by an IMO Convention (International Convention on Tonnage Measurement of Ships, 1969 (London-Rules)), which applies to all ships built after July 1982. In accordance with the Convention, the correct term to use now is GT, which is a function of the moulded volume of all enclosed spaces of the ship.
It is calculated by using the formula :GT = K \cdot V, where
V = total volume in m³ and
K = a figure from 0.22 up to 0.32, depending on the ship’s size (calculated by :K = 0.2 + 0.02 \cdot\log_{10}V). GT is consequently a measure of the overall size of the ship.
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 moulded volume of all cargo spaces of the ship.
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.
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 foot of capacity.
Panama Canal Tolls, from the
Panama Canal Authority. Retrieved May 10,
2006.
Thames Measurement is another volumetric system, generally used for small vessels such as
yachts; it uses a formula based on the vessel's length and beam.
Many people in many countries, including those professional people working in maritime industries for many years or even in their lifetime, often confuse "Tonnage" and "Ton". Please note that "Tonnage" refers to the unit of a ship's volume in measurement for registration and "Ton" refers to the unit of weight. They are totally different in concept.
Weight measurements
While not "tonnage" in the proper sense, the following methods of ship measurement are often incorrectly referred to as such:
Displacement (fluid) is the actual total weight of the vessel. It is often expressed in long tons or in tonnes, and is calculated simply by multiplying the volume of the
hull (watercraft) below the waterline (ie. the volume of water it is displacing) by the density of the water. (Note that the density will depend on whether the vessel is in fresh or salt water, or is in the tropics, where water is warmer and hence less dense.) For example, in sea water, first determine the volume of the submerged portion of the hull as follows: Multiply its length by its breadth and the draft, all in feet. Then multiply the product thereby obtained by the
block coefficient of the hull to get the hull volume in
cubic foot. Then multiply this figure by 64 (the weight of one cubic foot of seawater) to get the weight of the ship in pounds; or divide by 35 to calculate the weight in
long tons. Using the
SI or metric system : displacement (in tonnes) is volume (in m3) multiplied by the specific gravity of sea water (1.025 nominally).
The word "displacement" arises from the basic physical law, discovered by
Archimedes, that the weight of a floating object equates exactly to that of the water which would otherwise occupy the "hole in the water" displaced by the ship.
Lightship measures the actual weight of the ship with no
fuel, passengers,
cargo, water, etc. on board.
Deadweight (often abbreviated as
DWT for deadweight tonnes) is the displacement at any loaded condition minus the lightship weight. It includes the crew, passengers, cargo, fuel, water, and stores. Like Displacement, it is often expressed in long tons or in metric tons.
Ton types, by Gregory M. Walsh, Ocean Navigator. Retrieved May 10,
2006.
Origins
Historically, tonnage was the tax on
tuns (casks) of
wine that held approximately 252 gallons of wine and weighed approximately 2,240 pound (mass). This suggests that the unit of weight measurement, long tons (also 2,240 lb) and tonnage both share the same etymology. The confusion between weight based terms (deadweight and displacement (fluid)) stems from this common source and the eventual decision to assess dues based on a ship's deadweight rather than counting the tuns of wine. In 1720 the Builder's Old Measurement Rule was adopted to estimate deadweight from the length of keel and maximum breadth or beam (nautical) of a ship. This overly simplistic system was replaced by the Moorsom System in 1854 and calculated internal volume, not weight. This system evolved into the current set of internationally accepted rules and regulations.
When steamships came into being, they could carry less cargo, size for size, than sailing ships. As well as spaces taken up by boilers and steam engines, steamships carried extra fresh water for the boilers as well as coal for the engines. Thus, to move the same volume of cargo as a sailing ship, a steamship would be considerably larger than a sailing ship.
"Harbour Dues" are based on tonnage. In order to prevent steamships operating at a disadvantage, various tonnage calculations were established to minimise the disadvantage that the extra space requirements of steamships presented. Rather than charging by length or displacement etc, charges were calculated on the viable cargo space. As commercial cargo sailing ships are now largely extinct,
Gross Tonnage is becoming the universal method of calculating ships dues, and is also a more straight-forward and transparent method of assessment.
See also
References
- The Oxford Companion To Ships & The Sea, by I. C. B. Dear and Peter Kemp. Oxford University Press, 1979. ISBN 0-19-860616-8
- Ship Design and Construction, Volume II; Thomas Lamb, Editor. Society of Naval Architects and Marine Engineers, 2004. ISBN 99909-0-620-3
Tonnage is a measure of the size or cargo capacity of a
ship. The term derives from the taxation paid on
tuns of wine, and was later used in reference to the weight of a ship's cargo; however, in modern maritime usage, "tonnage" specifically refers to a calculation of the volume or cargo volume of a ship. The term is still sometimes incorrectly used to refer to the weight of a loaded or empty vessel.
Measurement of tonnage can be less than straightforward, not least because it is used to assess fees on
commerce shipping.
Tonnage measurements
Gross Register Tonnage (
GRT) represents the total internal
volume of a vessel, with some exemptions for non-productive spaces such as crew quarters; 1 gross register ton is equal to a volume of 100
cubic foot (2.83 cubic metre). This calculation is complex; a hold can, for instance, be assessed for cereal (accounting for all the air space in the hold) or for
bales (exempting the spaces between structural frames). Gross register tonnage was replaced by
gross tonnage in 1994 under the Tonnage Measurement convention of 1969, but is still a widely used term in the industry.
CWP Handbook of Fishery Statistical Standards. Retrieved May 10,
2006.
International Convention on Tonnage Measurement of Ships, 1969, International Maritime Organisation. Retrieved May 10, 2006.
Net Register Tonnage (
NRT) is the volume of cargo the vessel can carry; ie. the Gross Register Tonnage less the volume of spaces that will not hold cargo (e.g.
engine compartment, Ship's wheel station,
crew spaces, etc., again with differences depending on which
port or
country is doing the calculations). It represents the volume of the ship available for transporting freight or
passengers. It was replaced by
net tonnage in 1994, under the Tonnage Measurement convention of 1969.
Gross Tonnage (
GT) refers to the volume of all ship's enclosed spaces (from keel to funnel) measured to the outside of the hull framing. It is always larger than
gross register tonnage, though by how much depends on the vessel design. It was a measurement of the enclosed spaces within a ship expressed in "tons" – a unit which was actually equivalent to 100 cubic feet.
Tonnage measurements are now governed by an IMO Convention (International Convention on Tonnage Measurement of Ships, 1969 (London-Rules)), which applies to all ships built after July 1982. In accordance with the Convention, the correct term to use now is GT, which is a function of the moulded volume of all enclosed spaces of the ship.
It is calculated by using the formula :GT = K \cdot V, where
V = total volume in m³ and
K = a figure from 0.22 up to 0.32, depending on the ship’s size (calculated by :K = 0.2 + 0.02 \cdot\log_{10}V). GT is consequently a measure of the overall size of the ship.
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 moulded volume of all cargo spaces of the ship.
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.
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 foot of capacity.
Panama Canal Tolls, from the
Panama Canal Authority. Retrieved May 10,
2006.
Thames Measurement is another volumetric system, generally used for small vessels such as
yachts; it uses a formula based on the vessel's length and beam.
Many people in many countries, including those professional people working in maritime industries for many years or even in their lifetime, often confuse "Tonnage" and "Ton". Please note that "Tonnage" refers to the unit of a ship's volume in measurement for registration and "Ton" refers to the unit of weight. They are totally different in concept.
Weight measurements
While not "tonnage" in the proper sense, the following methods of ship measurement are often incorrectly referred to as such:
Displacement (fluid) is the actual total weight of the vessel. It is often expressed in
long tons or in tonnes, and is calculated simply by multiplying the volume of the
hull (watercraft) below the waterline (ie. the volume of water it is displacing) by the density of the water. (Note that the density will depend on whether the vessel is in fresh or salt water, or is in the tropics, where water is warmer and hence less dense.) For example, in sea water, first determine the volume of the submerged portion of the hull as follows: Multiply its length by its breadth and the draft, all in feet. Then multiply the product thereby obtained by the block coefficient of the hull to get the hull volume in cubic foot. Then multiply this figure by 64 (the weight of one cubic foot of seawater) to get the weight of the ship in pounds; or divide by 35 to calculate the weight in long tons. Using the SI or metric system : displacement (in tonnes) is volume (in m3) multiplied by the specific gravity of sea water (1.025 nominally).
The word "displacement" arises from the basic physical law, discovered by
Archimedes, that the weight of a floating object equates exactly to that of the water which would otherwise occupy the "hole in the water" displaced by the ship.
Lightship measures the actual weight of the ship with no
fuel, passengers,
cargo, water, etc. on board.
Deadweight (often abbreviated as
DWT for deadweight tonnes) is the displacement at any loaded condition minus the lightship weight. It includes the crew, passengers, cargo,
fuel, water, and stores. Like Displacement, it is often expressed in long tons or in metric tons.
Ton types, by Gregory M. Walsh, Ocean Navigator. Retrieved May 10,
2006.
Origins
Historically, tonnage was the tax on
tuns (
casks) of wine that held approximately 252 gallons of wine and weighed approximately 2,240 pound (mass). This suggests that the unit of weight measurement, long tons (also 2,240 lb) and tonnage both share the same etymology. The confusion between weight based terms (
deadweight and
displacement (fluid)) stems from this common source and the eventual decision to assess dues based on a ship's
deadweight rather than counting the tuns of wine. In 1720 the
Builder's Old Measurement Rule was adopted to estimate deadweight from the length of keel and maximum breadth or
beam (nautical) of a ship. This overly simplistic system was replaced by the Moorsom System in 1854 and calculated internal volume, not weight. This system evolved into the current set of internationally accepted rules and regulations.
When steamships came into being, they could carry less cargo, size for size, than sailing ships. As well as spaces taken up by boilers and steam engines, steamships carried extra fresh water for the boilers as well as coal for the engines. Thus, to move the same volume of cargo as a sailing ship, a steamship would be considerably larger than a sailing ship.
"Harbour Dues" are based on tonnage. In order to prevent steamships operating at a disadvantage, various tonnage calculations were established to minimise the disadvantage that the extra space requirements of steamships presented. Rather than charging by length or displacement etc, charges were calculated on the viable cargo space. As commercial cargo sailing ships are now largely extinct,
Gross Tonnage is becoming the universal method of calculating ships dues, and is also a more straight-forward and transparent method of assessment.
See also
References
- The Oxford Companion To Ships & The Sea, by I. C. B. Dear and Peter Kemp. Oxford University Press, 1979. ISBN 0-19-860616-8
- Ship Design and Construction, Volume II; Thomas Lamb, Editor. Society of Naval Architects and Marine Engineers, 2004. ISBN 99909-0-620-3
HM Revenue & Customs: International - Tonnage Tax
International - Tonnage Tax. Following extensive consultation the Tonnage Tax - an optional regime for shipping companies - was introduced into the UK tax ...
HM Revenue & Customs: Tonnage Tax
Tonnage Tax. Earlier this year, following discussions with the European Commission, HMRC published a Technical Note containing draft legislation amending the UK Tonnage ...
Tonnage - Wikipedia, the free encyclopedia
Tonnage is a measure of the size or cargo capacity of a ship. The term derives from the taxation paid on tuns of wine, and was later used in reference to the weight of a ship's ...
Cold Tonnage Books
Specializes in new and out of print, collectible science fiction, fantasy, horror and the supernatural first editions. Offers hardcovers, vintage paperbacks, pulps, and magazines.
Cold Tonnage Books 11885 - Weirdmonger.
Nearly 400 pages: collects sixty-seven short, weird stories, all written and published between 1987-1999. LIMITED HARDCOVER EDITION: ''This Hardcover Edition of Weirdmonger is ...
International Convention on Tonnage Measurement of Ships, 1969
Adoption: 23 June 1969 Entry into force: 18 July 1982 Introduction Gross tons and net tons Introduction The Convention, adopted by IMO in 1969, was the first successful attempt to ...
Current tonnage - Bibby International Services IOM Ltd
Bibby International Services Crew Management ... Bibby International Services (I.O.M.) Limited Providing Crew Management Solutions to the Marine Industry
Tonnage Conversion Tool
Monitoring and Evaluation of real nappy schemes ... Tonnage Conversion Tool WRAP have created an online tool to be used by real nappy schemes to help local authorities and nappy ...
Registration/Tonnage
Full Registration is required for a number of reasons; mortgage, title, insurance, commercial operation abroad.
RYA - Knowledge Base - Technical - Tonnage Surveys
