HD Hyundai Samho is building a 177,000-cubic-meter LNG carrier with three cargo tanks at its Yeongam shipyard in South Jeolla — the first large LNG vessel with a three-tank configuration ever constructed by a Korean shipbuilder.

The design cuts one tank from the standard four-tank layout while adding 3,000 cubic meters of loading capacity to the conventional 174,000-cubic-meter class. By eliminating non-cargo structures and equipment that previously sat between tanks, the shipyard rearranged the internal hull space and extended each individual cargo tank by up to 55% in length, according to the Korean shipbuilding industry on the 28th.

The commercial logic is straightforward. Ships hauling LNG from the United States and the Middle East to Asia and Europe gain from carrying more cargo per voyage within fixed hull dimensions, cutting fuel consumption and unit shipping costs. On the same 177,000-cubic-meter hull, the three-tank vessel loads roughly 3,000 cubic meters more LNG than a four-tank equivalent.

There is also a cost lever on the construction side. Korean shipyards pay license royalties to France's GTT, which holds the core cargo containment technology, generally understood to run around 5% of the cargo tank area. Dropping one tank removes one cofferdam — the space between tanks — shrinking total membrane area and lowering both material input and the royalty bill.

Sloshing risk

The engineering barrier explains why nobody has done this at scale. Fewer tanks mean bigger tanks, and bigger tanks intensify "sloshing" — the surge of LNG against internal structures that can damage the cargo containment system during operation. Building large LNG carriers with a three-tank configuration demands construction methods and safety verification that most yards have not attempted.

Chinese rivals have the paperwork but not the steel. In 2023, Hudong–Zhonghua Shipbuilding secured technology certification for a 174,000-cubic-meter three-tank LNG carrier from five major international classification societies, including the American Bureau of Shipping (ABS), yet has not built a vessel. HD Hyundai Samho's hull under construction at Yeongam puts Korea ahead on delivered hardware, a position the industry views as strengthening Korean yards' hand in future LNG carrier order contests.

The design also helps offset Korean price disadvantages against Chinese bids, since higher transport efficiency and lower construction costs give owners more value per dollar even where the headline newbuild price runs higher.

Ryu Min-cheol, a professor at Korea Maritime and Ocean University, said: "Building three cargo tanks implies higher pressures could occur, which suggests HD Hyundai has found a safe construction method." He added: "On the assumption there are no safety issues, the surface area would be smaller than with four cargo tanks, reducing the amount of materials and allowing the ship price to come down further."

Royalty endgame

The three-tank debut feeds into a broader Korean campaign to localize LNG cargo containment and stop paying GTT. Seoul designated LNG cargo tank localization last year as one of its "15 ultra-innovation economy leading projects" and is accelerating technology demonstration.

Korea's first attempt stalled. The KC-1 tank, developed in 2004 and led by KLT, a subsidiary of KOGAS, reached the demonstration stage before a "cold spot" — an icing phenomenon in which the cargo tank's outer wall temperature fell below the allowable range — halted ship operations and derailed commercialization.

Second-generation development is now moving faster, with each of the three major yards pursuing its own system. Samsung Heavy Industries received technology certification for its in-house KC-2C tank from DNV of Norway and three other international classification societies. HD Hyundai Heavy Industries obtained certifications from Lloyd's Register and the Korean Register, while Hanwha Ocean collected certificates from five societies including DNV.

KOGAS plans to place an order within this year for a demonstration vessel carrying second-generation cargo tank technology, with the winning shipbuilder's system moving into actual sea-going trials.

For LNG charterers and fleet owners, the near-term implication is incremental: modestly more cargo per voyage and a cheaper hull. The longer game is structural — if Korean yards pair three-tank efficiency with a royalty-free containment system, the cost gap with Chinese builders widens from both directions at once.