La Noumbi

La Noumbi is a floating production storage and offloading (FPSO) unit operated by Perenco. The vessel, converted from the former Finnish Aframax crude oil tanker Tempera by Keppel Corporation, will replace an older FPSO unit in the Yombo field off the Republic of Congo in 2018.

Built at Sumitomo Heavy Industries in Japan in 2002, Tempera was the first ship to utilize the double acting tanker (DAT) concept in which the vessel is designed to travel ahead in open water and astern in severe ice conditions. Tempera and her sister ship Mastera, built in 2003, were used mainly to transport crude oil, year-round, from the Russian oil terminal in Primorsk to Neste Oil refineries in Porvoo and Naantali. In 2015, Neste sold Tempera to the oil and gas company Perenco for conversion to an FPSO.

Although icebreaking cargo ships had been built in the past, their hull forms were always compromises between open water performance and icebreaking capability. A good icebreaking bow, designed to break the ice by bending it under the ship's weight, has very poor open water characteristics and is subjected to slamming in heavy weather while a hydrodynamically efficient bulbous bow greatly increases the ice resistance. However, already in the late 1800s captains operating ships in icebound waters discovered that sometimes it was easier to break through ice by running their vessels astern. This was because the forward-facing propellers generated a water flow that lowered the resistance by reducing friction between the ship's hull and ice. These findings resulted in the adoption of bow propellers in older icebreakers operating in the Great Lakes and the Baltic Sea, but as forward-facing propellers have a very low propulsion efficiency and the steering ability of a ship is greatly reduced when running astern, it could not be considered a main operating mode for merchant ships.

For this reason it was not until the development of electric podded propulsion, ABB's Azipod, that the concept of double acting ships became feasible. The superiority of podded propulsion in icebreaking merchant ships, especially when running astern, was proved when Finnish product tankers Uikku and Lunni were converted to Azipod propulsion in 1993 and 1994, respectively. Even though the ships were originally designed with icebreaking capability in mind, after the conversion ice resistance in level ice when running astern was only 40% of that when breaking ice ahead despite the ships being equipped with an icebreaking bow and not designed to break ice astern.

Following the successful operation of the Azipod-converted tankers Uikku and Lunni in the Northern Sea Route, Kværner Masa-Yards Arctic Research Centre developed the first double acting tanker concept in the early 1990s. The 90,000 DWT tankers were designed to transport oil and gas condensate from the Pechora Sea in the Russian Arctic, where ice conditions during winter can be considered moderate and the ships would operate mainly in astern mode, first to Murmansk and then Rotterdam, where most of the distance can be travelled in open water year round. Other early double acting concepts included a similar ship with an icebreaking bow that would be utilized in summer time when the ship was traveling in areas with low ice concentration but with a risk of colliding with multi-year ice blocks.

In early 2000s Fortum Shipping, the transportation arm of the Finnish energy company Fortum, started a major fleet renewal program to increase the efficiency and reduce the average age of its vessels. The program also included replacing the company's old tankers, such as the 90,000-ton Natura, that were used to transport crude oil to the company's oil refineries in the Gulf of Finland. The old ships had traffic restrictions during the worst part of the winter because of their lower ice class of 1C and could not deliver their cargo all the way to the refineries in Porvoo and Naantali because they were denied icebreaker assistance. When this happened, the oil had to be transported to smaller ships of higher ice class at the edge of the ice — a practice that was both uneconomical and hazardous.

To solve these problems Kværner Masa-Yards Arctic Research Centre developed a new 100,000 DWT Aframax tanker concept together with Fortum Shipping, which ordered two vessels from Sumitomo Heavy Industries in 2001. The new ships were designed to the highest Finnish-Swedish ice class, 1A Super, and to be capable of operating in all ice conditions encountered in the Baltic Sea. The possibility to operate in the Pechora Sea was also taken into account in the design process. Extensive ice model tests confirmed the vessel's operational capability in level ice, rubble fields, ice channels and ridges.

The world's first double acting tanker and the largest 1A Super class oil tanker at that time, Tempera, was delivered from Yokosuka shipyard in late August 2002. She was awarded the Ship Of The Year 2002 award by the Society of Naval Architects of Japan (SNAJ). The second ship, Mastera, was delivered in the following year. Both ships were named after the company's oil products. While the price of the contract was not made public, the company later admitted that the 60–70 million euro estimate was "quite close to the truth". The ships were owned by ABB Credit, which leased them to Fortum for ten years. The leasing business was later sold to SEB Leasing.