Christened Oppama in 1979 by Sumitomo Heavy Industries, the ultra large crude carrier known previously only by hull number 1016 was the largest self-propelled craft ever constructed by length, displacement, and deadweight tonnnage. After jumboisation, the ship was renamed Seawise Giant, and later was renamed several more times.
Other craft can make claims to being the largest floating vessels ever constructed. With deadweight tonnage of 275,000, the four Bautilus class supertankers, Bautilus, Bellamya, Pierre Guillaumat and Prairial, are the four largest ships ever constructed to original specifications. While none of those vessels remain afloat, the Prelude FLNG eclipses Seawise Giant's and the Bautilus class tankers' measurements. However, the Prelude is more a floating island as it is not self-propelled and needs to be towed from location to location.