VLCC tanker Tohdoh was built by Mitsui Eng. & Shipbuilding Co.,Ltd. in 1991. She was owned and operated by NYK Line. In 2008, she was sold to MODEC for US$42.5 million. MODEC renamed the ship Ohdoh and started her conversion into FPSO vessel. Conversion was done by SembCorp Marine at the Jurong Shipyard in Singapore. On 1 May 2010, the vessel was renamed Kwame Nkrumah MV21, and on 15 May 2010 she started her trip for her base in the Western Coast of Ghana. She arrived in Ghana on 21 June 2010. The vessel is estimated to cost US$875 million.
The vessel has a width of 65 metres (213 ft) and is 330 metres (1,080 ft) in length. It is about the size of three standard football fields put together.
The FPSO Kwame Nkrumah uses the biggest turret ever constructed in the oil industry. It can process 120,000 barrels per day (19,000 m3/d) of oil and 160 million cubic feet (4.5×10^6 m3) of production gas, with a storage capacity of 1.6 million barrels (250×10^3 m3). It has 17 modules weighing more than 12,500 tonnes installed on it. The modules include a water treatment plant, a crude separation plant, a chemical injection plant, a gas processing and injection plant, a 120-room accommodation. The vessel has the capacity to generate energy for its work. It receives fluid from a sub sea oil well and processes it on board to produce crude oil which is then exported to a refinery by shuttle tankers.