Seawise Giant

Seawise Giant also known as Jahre Viking, Happy Giant, Knock Nevis and Mont is the worlds largest ever ship, an Ultra Large Crude Oil Carrier.


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260,851 TONS


1,504 FEET


226 FEET







Seawise Giant was the largest ship built in the 20th Century with a volume of 260,851 Gross Registered Tons. As oil tankers have to be built with double hulls since the Exxon Valdez spillage in Alaskan waters March 27th 1989, it is unlikely any new tankers will exceed this size. The next type of vessel that could eventually exceed the tonnage of Seawise Giant is a floating city. A few of these ships could soon become a reality as some have already been designed.

Construction of this oil tanker began in 1979 for a Greek shipping magnate. As a result of the oil embargo in the 1970s, the original owner was declared bankrupt before his ship could be completed. This led to the Hong Kong shipping magnate Mr. C. Y. Tung buying the incomplete ship under an agreement the builders would increase its length so the Dead Weight Tonnage (full load) could be increased from 480,000 to 564,763 tons.

Click on image to enlarge.

Click to enlarge

Seawise Giant was first operated in the Gulf of Mexico and Caribbean Sea. She was later transferred to the Persian Gulf to be used for exporting oil from Iran. While Seawise Giant was traveling through the Hormus Straits in 1986, during the Iran/Iraq war, she was attacked by Iraqi jets and hit with Exocet missiles. The extensive damage caused by these attacks led to her sinking in shallow waters at Kharg Island.

A few months after the end of the Iran-Iraq War, August 1988, Norman International bought Seawise Giant, had her refloated, repaired by the Keppel Shipyard in Singapore, and renamed her Happy Giant. The prestige of owning the world’s largest ship seems to have been the main reason this company made the purchase.

By 1999 she had been sold to the Norwegian company Jahare Wallem to be operated under the name Jahre Viking. This ship is so large, four football fields could be laid end to end on her deck, braking distance is about three and a half miles and fully loaded she sits 80 feet in the water.

Jahre Viking

The Oppama shipyard was established in the early 1970s as a large modern yard with a building dock 1,800 feet long, 260 feet wide and 41 feet deep for the construction of ultra large tankers and bulkers. On June 1st 1997, the Oppama yards name was changed to Yokosuka. Although they are unlikely to build any more ships as large as Seawise Giant, they still build large tankers and bulkers.

C. Y. Tung was born in Shanghai/China in 1912. His interest in shipping began when he found work as a shipping clerk in 1930. Tung fled with his family to Hong Kong after the communists were victorious in the Chinese Civil War 1945-1949. By 1970, he had become one of the worlds leading independent ship owners operating a fleet of more than 150 ships. As well as owning the world’s largest ship Seawise Giant, he also bought the world’s largest Trans Atlantic liner Queen Elizabeth in 1970. C. Y. Tung died April 15th 1982 aged 71. As his son Tung Chee-Hwa took control of the company at that time, he became one of Hong Kong’s most influential businessmen. This led to him taking over as chief executive of Hong Kong when Britain handed the island back to China July 1st 1997.

In March 2004, Jahre Viking was sent by its new owner, First Olsen Tankers, to the Dubai drydocks to be refitted as a floating storage and offloading unit. Under the name Knock Nevis, she began operating at the Al Shaheen oilfield in waters of Qatar.

In December 2009, this vessel was sold to Indian breakers and renamed Mont for her final journey. After clearing Indian customs, she was intentionally beached in India for ship breaking. She was photographed beached for scrapping at Alang, India on 4 January 2010. Ship Breaking Information.

The other six tankers to break the 500,000 dwt mark were:

Battilus 553,662 dwt 1976 - 1985
Bellamya 553,662 dwt 1976 - 1986
Pierre Guillaumat 555,051 dwt 1977 - 1983 largest ship ever constructed as designed
Esso Atlantic 516,000 dwt 1977 - 2002
Esso Pacific 516 dwt 1977 - 2002
Prairial 554,974 dwt 1979 - 2003

The first four double hull tankers over 400,000 tons were built for the Hellespont Shipping Corporation of Greece in 2000 with all being registered under the Marshall Islands. The first of these sisters at 442,000 dwt, the MV Hellespont Alhambra, was registered with the Marshall Islands on March 7th 2002, with the Hellespont Metropolis following on June 3rd. The last two sister ships in the series, the Hellespont Fairfax and Hellespont Tara joined the Marshall Islands register later that year.

Photos and information of many more tankers can be found at

Pierre Guillaumat

If cruise ships keep growing in size at the rate they are, it now seems possible a cruise ship could soon be built as large as Knock Nevis. The largest cruise ships to hold the title largest passenger ship in the world are:

Carnival Destiny, 1996, 101,353 grt, 893 feet long, 116 feet wide.

Grand Princess, 1998, 109,000 grt, 951 feet long, 118 feet wide.

Voyager of the Seas, 1999, 142,000 grt, 1,020 feet long, 126 feet wide.

Queen Mary 2, 2003, 151,000 grt, 1,131 feet long, 135 feet wide.

Freedom of the Seas, 2006, 158,000 grt, 1,112 feet long, 126 feet wide.

Oasis of the Seas, 2009, 220,000 grt, 1,181 feet long, 154 feet wide, this ship will enter service late 2009.

Knock Nevis, 1981, 260,000 grt, 1,504 feet long, 226 feet wide.

USS Nimitz aircraft carrier, 1975, ?GRT, 1,092 feet long, 134 feet wide hull - 252 feet wide flight deck.

Questions that may be asked are: what is GRT (Gross Registered Tons).

Each ship has to be registered in size as harbor duties are set by the ships bulk. The measurement normally used for ships is Gross Registered Tons. This is a volumetric measurement that is worked out on the basis that, 100 cubic feet is the equivalent to one Gross Registered Ton. Warships are normally registered under Displacement Tonnage. This is calculated by the weight of water displaced by the ship after completion. Each warship normally has three different weights, light, standard and full load. Unless stated otherwise, the ships weight should be taken as standard. Crude oil tankers use GRT and Dead Weight Tons, DWT meaning the weight of water the ship displaces when fully loaded. GRT is probably the best way to compare the actual size of ships as it is worked out on volume. The larger the GRT, the larger in dimension the hull and superstructure are. It is hard to compare the actual bulk of a warship against cruise ships and tankers as it is hard to get the GRT of the largest warships ever built, the 9 Nimitz class aircraft carriers.

How does Freedom of the Seas have a larger GRT than QM2 as she is shorter and narrower.

The upper decks of QM2 step in from the main hull of the ship plus she does not have full height superstructure right at the stern as does Freedom of the Seas, so less volume.

How do cruise ships have so large a GRT giving they are 3-4 hundred feet shorter than Knock Nevis.

Knock Nevis sits about 80 feet in the water when fully loaded with only around 30 feet of hull above the waterline. The largest cruise ships sit about 200 feet above the waterline with only about 30 feet of their hull in the water. Cruise ships are shorter and narrower but a lot taller.

Cruiseship List