page_title: Passenger ship
section_title: Measures of size
hierarchical_section_title: Passenger ship / Description / Measures of size
caption_attribution_description: English: Oasis of the Seas entering the port at Nassau, Bahamas in January 2010. Suomi: Oasis of the Seas saapumassa satamaan Nassaussa, Bahamalla Tammikuussa 2010. العربية: كروز - السفينة من فئة الواحة، بنيت في أوروبا لصالح شركة في كوريا الجنوبية. Български: „Oasis of the Seas“ край бреговете на Насау, Бахамските острови, Януари 2010&#160;г. کوردی: وێنەی کەشتییەکە. Deutsch: Oasis of the Seas. 日本語: 世界最大の客船「オアシス・オブ・ザ・シーズ」. ქართული: Oasis of the Seas 2010 წლის იანვარში. 한국어: 오아시스 오브 더 씨즈.oasis of the seas. Nederlands: Oasis of the Seas. De Oasis of the Seas in Nassau. Română: Nava în Nassau, Bahamas, în ianuarie 2010;. Slovenščina: Oasis of the Seas. Oasis of the Seas - največja potniška križarka na svetu, zgrajena v finski ladjedelnici Turku. Svenska: Kryssningsfartyget M/S&#160;Oasis of the Seas är världens näst största kryssningsfartyg efter systerfartyget M/S&#160;Allure of the Seas. ไทย: เรือโอเอซิสออฟเดอะซีส์. เอ็มเอส โอเอซิสออฟเดอะซีส์ ขณะเทียบท่าที่เมืองนัสซอ ประเทศบาฮามัส. Українська: Круїзний лайнер Oasis of the Seas.
context_page_description: A passenger ship is a merchant ship whose primary function is to carry passengers on the sea. The category does not include cargo vessels which have accommodations for limited numbers of passengers, such as the ubiquitous twelve-passenger freighters once common on the seas in which the transport of passengers is secondary to the carriage of freight. The type does however include many classes of ships designed to transport substantial numbers of passengers as well as freight. Indeed, until recently virtually all ocean liners were able to transport mail, package freight and express, and other cargo in addition to passenger luggage, and were equipped with cargo holds and derricks, kingposts, or other cargo-handling gear for that purpose. Only in more recent ocean liners and in virtually all cruise ships has this cargo capacity been eliminated.
  While typically passenger ships are part of the merchant marine, passenger ships have also been used as troopships and often are commissioned as naval ships when used as for that purpose.
context_section_description: Because of changes in historic measurement systems, it is impossible to make meaningful and accurate comparisons of ship sizes over time beyond length.  Three alternative forms of measurement are ship volume, weight, and weight of water it displaces.  A fourth, deadweight tonnage (DWT), is a measure of how much mass a ship can safely carry, and is thus more relevant to measuring cargo vessels than passenger ships.
  Historically, gross register tonnage (GRT) was a measure of the internal volume of certain enclosed areas of a ship divided into "tons" equivalent to 100 cubic feet of space (about 2.83 m³).  The displacement (or displacement tonnage) is a measure of both a ship's weight and the weight of water (measured by volume and converted into tons) it displaces, which are one and the same by Archimedes' principle.  While seemingly straightforward, it has four variants in measure, Loaded displacement, Light displacement, Normal displacement, and Standard displacement.  Of these, the first is most appropriate to measuring a passenger vessel.
  Gross tonnage (GT) is a comparatively new measure, only adopted in 1982 to replace GRT.  It is calculated based on "the moulded volume of all enclosed spaces of the ship", and is used to determine things such as a ship's manning regulations, safety rules, registration fees, and port dues.  It is produced by a mathematical formula, and does not distinguish between mechanical and passenger spaces, and thus is not directly comparable to historic GRT measurements.
  While a high displacement can indicate better sea keeping abilities, gross tonnage is nowadays promoted as the most important measure of size for passenger vessels, as the ratio of gross tonnage per passenger – the Passenger/Space Ratio – gives a sense of the spaciousness of a ship, an important consideration in cruise liners where the onboard amenities are of high importance.
  Historically, a ship's GRT and displacement were somewhat similar in number.  For example, RMS Titanic, put in service in 1912, had a GRT of 46,328 and a displacement reported at over 52,000 tons. Similarly, Cunard Line's mid-1930s RMS Queen Mary and RMS Queen Elizabeth were of approximately 81,000 – 83,000 GRT and had displacements of over 80,000 tons.
  Today, due to changes in construction, engineering, function, architecture, and, crucially, measurement system – which measures functionally all of a ship's internal volume, not just part of it – modern passenger ships' GT values are much higher than their displacements. The Cunard Queens' current successor, the 148,528 GT  RMS Queen Mary 2, has been estimated to only displace approximately 76,000 tons. With the completion in 2009 of the first of the over 225,000 GT Oasis Class dedicated cruise ships, Oasis of the Seas, passenger ships' displacements have finally risen to 100,000 tons, well less than half their GT.
  This new class is characteristic of an explosive growth in gross tonnage, which has more than doubled from the largest cruise ships of the late 1990s.  This reflects the much lower relative weight of enclosed space in the comparatively light superstructure of a ship versus its heavily reinforced and machinery-laden hull space, as cruise ships have grown slab-sided vertically from their maximum beam to accommodate more passengers within a given hull size.
caption: MS Oasis of the Seas (2009), 225,282 GT, approximately 100,000 tons displacement
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