Singapore-based Ocean Network Express (ONE) is chartering a series of ultra-large containerships under a long-term basis from Japanese tonnage provider Shoei Kisen.

The liner company said it has penned a letter of intent to charter six newbuildings of more than 24,000 teu for 15 years. The company did not disclose the charter rate but said the vessels will be the world’s largest containerships.

Delivery of the ultra-large boxship newbuildings is slated for 2023 and 2024.

“The newbuildings are planned to be built by the consortium of Imabari Shipbuilding and Japan Marine United,” said ONE.

“This new class of ships will join our core fleet and forms part of our ongoing strategy to introduce large, modern, and fuel-efficient vessels to further strengthen our fleet competitiveness.”

ONE claims that the current largest containerships that have been built are less than 24,000-teu.

“The six new ultra-large containerships with capacity exceeding 24,000-teu will help bring economies of scale and significantly lower carbon emissions through a state-of-the-art hull design that aims to maximize cargo intake and minimise fuel consumption.”

ONE, which is controlled by Japanese shipping giants NYK Line, Mitsui OSK Line and K Line, added that the vessels will be equipped with exhaust gas cleaning systems to meet International Maritime Organization sulphur regulations.

“This initiative represents ONE’s ongoing efforts to offer more competitive and best-in-class services to our customers through the introduction of ULCS [ultra-large containerships] that have a decreased environmental impact. It reaffirms our commitment to operational excellence, business sustainability and environmental protection.”

ONE is the second line company to disclosed that it is adding ultra-large containerships to its fleet this week.

Yesterday, German liner operator Hapag-Lloyd announced that it has signed an order for six 23,500-teu newbuildings at Daewoo Shipbuilding & Marine Engineering (DSME) for delivering between April and December 2023.

It did not disclose the price of the dual-fuelled vessels, which will be able to run on LNG and conventional fuels, but shipbuilding sources put it in the region of $165m apiece.

Hapag-Lloyd said the new containership will be deployed on the Europe-Far East routes as part of THE Alliance.

"With the investment in six ultra-large container vessels, we will not only be able to reduce slot costs and improve competitiveness on the Europe-Far East trade, but also take a significant step in modernizing our fleet," said Rolf Habben Jansen, chief executive of Hapag-Lloyd.

"Additionally we will further reduce our environmental impact."

Hapag-Lloyd operates its services as a member of THE Alliance together with partners Japan's Ocean Network Express (ONE), Taiwanese operator Yang Ming Line and HMM of South Korea.