Well, this might be a weird question, but I have always wondered about it. I was looking/researching at cruises and their sizes, when it would list how many tons they weigh.
What confuses me is how some cruise ships that are longer than others, weigh less than the smaller ones. For example, there could be a ship at 960 ft. and it weighs 90,000 tons. But then another ship is 950 ft and it weighs 100,000+ tons. Why is that? Does it depend on the materials used or what's onboard the ship?
If someone could let me know...that would be great. Just another fact that I could learn about cruises.
Samantha, your question is a very good one. Part of the answer is the weight of the materials used, that is, the ship's steel structure, engines, and so on. Some ships are designed to be longer while others are designed to be wider. Then there is the Panamax problem. Hey, just for fun do you know what panamax means?
"Tons" has nothing to do with the weight of the ship. That is how they measure the capacity of the ship. 1 "traveler ton" is about 14 cubic meters. If you are going by "gross tons" figure about 5 gross tons to one traveller ton.
It's a great question, Samantha, and one that confounds many as there is no standard means of measuring it.
Gross tonnage refers to space or capacity, not weight or displacement. Typically, only the interior portions of the ship are counted, and I believe cabins are excluded. These areas are measured in cubic feet, as Larry noted, and then converted to "tons."
as others have indicated already, if a ship is 100,000 gt or gross tons, that doesn't mean the ship has a mass of 100,000 t or metric tons. "Gross ton" is a measure of volumne rather than a measure of mass.
The following excerpt from Wikipedia shows that the word ton's original meaning stems from a measure of volumne, even though in everyday life it is usually being used as a measure of mass:
Quote:
The word ton or tonne is derived from the Old English tunne, and ultimately from the Old French tonne, and referred originally to a large cask with a capacity of 252 wine gallons, which holds approximately 2100 pounds of water. Such a barrel (of any similar volume) is still called a tun in British English, but this usage is dying out.
One register ton, the unit in which a ship's size is measured, is defined as 100 cubic feet or 2.83 cubic meters. The old way of measuring ships in "gross registered tons" has been replaced by the gross tonnage, which is a non-dimensional value, i.e. while a ship was previously "100,000 grt" it is now "gt 100,000". Yet, virtually everybody (including myself" continue to write it "100,000 gt" - even though it is not correct, strictly spoken.
The gross tonnage includes all enclosed spaces of the ship, while for the calculation of the net tonnage crew quarters, command bridge, engine rooms, fuel (water, sewage, ...) tanks, storages etc. are deducted.
Cruise lines often speak about something they call the "space ratio", which is calculated by dividing the gross tonnage through the number of passengers a ship carries. With the above definitions I guess it is obvious that the space ratio is highly misleading because it is based on the gross tonnage rather than on the net tonnage, i.e. the amount of volumne available to passengers. As an example, the infamous "Titanic" and Royal Caribbean's "Empress of the Seas" are roughly the same size as far as their gross tonnage is concerned. However, their net tonnage is vastly different with "Empress of the Seas'" net tonnage being significantly larger due to the fact that she's a modern ship with smaller engine space, fuel bunkers etc.
Sadly, the Cruise Lines International Association (CLIA) has been teaching American travel agents an utterly wrong definition of the gross tonnage for years, defining it as the volumne of "all revenue-earning spaces".
Hope this wasn't way too much information for one posting.
Originally posted by Raoul Fiebig:
Sadly, the Cruise Lines International Association (CLIA) has been teaching American travel agents an utterly wrong definition of the gross tonnage for years, defining it as the volumne of "all revenue-earning spaces".
Ah - the reason for my own confusion. Yes, that was the definition told to us in our earlier years of cruising. Funny how some things stick. Thanks for the post, Raoul.
To the Panamax question.....does it mean to do the full panama?
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A ship specifically built to these dimensions is called a Panamax-max vessel. Of course no cruise ship has a draft of 12 meters, but there are quite a few ships which have been built to the maximum length, beam and height.
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