Background
Mitsui E&S DU is the Japanese license-builder for MAN B&W (Everllence) and WinGD (Sulzer lineage) slow-speed two-stroke marine diesel engines. The company holds the longest-running licensee relationships with both major OEMs:
- MAN B&W (Burmeister & Wain) since 1926: the oldest MAN B&W licensee anywhere in the world
- Sulzer (now WinGD) since 1948: among the oldest Sulzer licensees
The company’s production scale is significant in the Japanese context, though smaller than the Korean license-builders HHI-EMD and Hanwha Engine. Mitsui E&S DU dominates the Japanese-domestic market for low-speed two-stroke engines (~71% market share in 2024) and exports a smaller share to Asian and other shipyards.
This article covers Mitsui E&S DU’s corporate history, license relationships, production capacity, and strategic position within the global marine engine market.
Corporate context
Mitsui E&S Holdings
Mitsui E&S DU operates within the broader Mitsui E&S Holdings group (Mitsui Engineering & Shipbuilding renamed). Mitsui E&S Holdings is a major Japanese industrial firm, traceable to early-20th-century Mitsui zaibatsu activities. The group historically operated:
- Mitsui Engineering & Shipbuilding (MES): shipbuilding operations
- Marine engine business (now Mitsui E&S DU)
- Industrial machinery
- Other engineering subsidiaries
In 2021 Mitsui Engineering & Shipbuilding sold its shipbuilding business to Tsuneishi Shipbuilding, completing a substantial restructuring. The remaining business was renamed Mitsui E&S Holdings, focused on engine, machinery, and industrial activities without shipyards. The 2023 reorganisation that created Mitsui E&S DU continued this restructuring.
Tamano plant
The principal manufacturing facility is the Tamano plant in Okayama Prefecture, on Japan’s Seto Inland Sea coast. The Tamano facility:
- Was originally Mitsui Engineering & Shipbuilding’s Tamano shipyard
- Has long been the primary marine engine production site
- Continues as Mitsui E&S DU’s main facility
- Includes engine assembly, test bed, and component machining
After the 2021 sale of MES shipbuilding to Tsuneishi, the engine plant remained with Mitsui’s engine business (now Mitsui E&S DU).
Historical lineage
1926: B&W agreement
In 1926 Mitsui (then in earlier corporate identity within the broader Mitsui zaibatsu) signed a technical partnership agreement with Burmeister & Wain of Copenhagen for marine diesel engine licensing. This 1926 agreement is the oldest continuously held MAN B&W licensee relationship anywhere in the world.
The 1926 agreement provided:
- Manufacturing rights for B&W diesel engines in Japan
- Technology transfer and engineering support
- Joint engineering for production specifics
- Royalty payments to B&W on each engine built
Through the 1920s, 1930s, and 1940s Mitsui built B&W-licensed engines for Japanese merchant shipping. The relationship continued through World War II (with restricted operations) and resumed full activity post-war.
1948: Sulzer agreement
In 1948 Mitsui (now Mitsui Engineering & Shipbuilding) entered a technical agreement with Sulzer Brothers of Winterthur, Switzerland for marine diesel engine licensing. This 1948 agreement is among the oldest continuously held Sulzer licensee relationships.
The 1948 agreement gave Mitsui dual-OEM capability: building both B&W and Sulzer engines under license, depending on customer requirements. This dual relationship has continued through all subsequent OEM corporate restructurings (Sulzer → Wartsila NSD → Wartsila Switzerland → WinGD).
Continued operations
Through the post-war decades Mitsui Engineering & Shipbuilding became one of Japan’s major engine builders, producing thousands of marine engines for Japanese-built and international ships.
Diesel United Ltd. (separate company)
A related but distinct entity is Diesel United Ltd., formed as a joint venture between IHI Corporation and Hitachi Zosen for marine diesel engine production. Diesel United is separate from Mitsui’s engine business; the two companies have historically been competitors within the Japanese marine engine market, both holding MAN B&W (and historically Sulzer) licenses. Diesel United was eventually consolidated into Japan Engine Corporation J-ENG in 2017 in a separate corporate reorganisation.
2023 corporate reorganisation
Mitsui E&S DU formation
In April 2023 the marine engine business was reorganised as a separate entity: Mitsui E&S DU Co., Ltd. (“DU” refers to “Diesel United”-style designation though the entity is distinct from the historical Diesel United Ltd.). The reorganisation:
- Separated the engine business from other Mitsui E&S Holdings activities
- Provided cleaner corporate structure for license relationships with both Everllence and WinGD
- Aligned the entity name with current OEM partnerships
Continued license relationships
Mitsui E&S DU continues to hold both license relationships:
- Everllence (MAN-ES, MAN B&W lineage) — direct successor to the 1926 B&W relationship
- WinGD (Sulzer lineage) — direct successor to the 1948 Sulzer relationship
These two relationships are the longest-running marine diesel licensee partnerships globally; they are foundational to Japanese marine engine industry continuity.
Current production
Annual volume
For fiscal year 2023 (FY2023, the Japanese fiscal year typically running April 2023 through March 2024), Mitsui E&S DU produced:
- 155 large marine engines
- 3.16 million HP total (approximately 2.4 million kW)
For FY2024 (April 2024 - March 2025) the production plan was:
- 146 units / 3.04 million HP (approximately 2.3 million kW)
These figures put Mitsui E&S DU at roughly half of Hanwha Engine’s volume and roughly one-fifth of HHI-EMD’s volume. Within Japan, Mitsui E&S DU is the largest engine builder by share.
Cumulative milestones
- November 2024: Cumulative MITSUI-MAN B&W engine production reached 120 million horsepower (approximately 88 million kW)
Cumulative Sulzer/WinGD-licensed engine production figures are not separately disclosed but are also substantial.
Domestic Japanese market share
Mitsui E&S DU achieved approximately 71% domestic Japanese market share in 2024. This dominance reflects:
- Long relationships with Japanese shipbuilders (Imabari, Tsuneishi, Japan Marine United, others)
- Established service network across Japan
- Domestic preference for Japanese-built engines on Japanese-built ships
The remaining ~29% of Japanese market share goes principally to Japan Engine Corporation (J-ENG) (UE engines and licensed designs) and Kawasaki Heavy Industries.
Product range
Mitsui E&S DU builds the full slow-speed two-stroke engine range under license:
MAN B&W (Everllence) variants
- MC, MC-C, ME-B, ME-C (mainstream slow-speed two-stroke)
- ME-GI (LNG dual-fuel)
- ME-LGIM (methanol dual-fuel)
- ME-LGIP (LPG dual-fuel)
Bore range: typically up to 95 cm. Power range: ~3,500 kW to ~80,000 kW.
WinGD variants
- X-series (X35, X40, X52, X62, X72, X82, X92)
- X-DF (LNG dual-fuel, low-pressure Otto-cycle)
- X-DF2.0 with iCER
The dual-OEM capability allows Japanese shipyards to specify either MAN-ES or WinGD designs depending on customer preference, fuel choice, and commercial considerations.
Strategic position
Japanese engine production
Within Japan, marine engine production is split principally between:
- Mitsui E&S DU (~71% market share, MAN B&W + WinGD licenses)
- J-ENG (Japan Engine Corporation) (~25% market share, UE proprietary + MAN B&W + WinGD licenses)
- Kawasaki Heavy Industries (~4% market share, MAN B&W + UE licenses)
Global market position
Globally, Japanese engine production accounts for approximately 18% of slow-speed two-stroke kW. Japan is third behind South Korea (~50%) and China (~30%). Mitsui E&S DU’s share of global production is modest but represents a critical capability for Japanese maritime industry self-sufficiency.
Customer relationships
Principal customers are Japanese shipyards:
- Imabari Shipbuilding (Japan’s largest shipbuilder)
- Tsuneishi Shipbuilding (acquired Mitsui’s former shipyard in 2021)
- Japan Marine United (JMU)
- Namura Shipbuilding
- Various smaller Japanese yards
Limited export to non-Japanese yards. International sales are typically through customer pull (a non-Japanese owner specifying a Japanese-built ship with Japanese-built engine) rather than active export marketing.
License maintenance
Mitsui E&S DU’s two long-standing license relationships are competitive assets:
- Long history provides accumulated engineering knowledge
- Long-term relationships with OEM service organisations
- Established trust enables collaborative development on specific applications
- Continuous license renewal across major OEM corporate transitions (B&W → MAN B&W → MAN-ES → Everllence; Sulzer → Wartsila → WinGD)
Engineering capability
Tamano facility
The Tamano plant has substantial engineering capability:
- Engine assembly halls for engines up to 95 cm bore
- Component machining (some components manufactured on-site, others bought-in)
- Test bed for full-load engine commissioning
- Quality assurance and inspection facilities
- R&D and engineering support staff
Service capability
In addition to new-build engine production, Mitsui E&S DU operates a service network supporting:
- Mitsui-built engines globally
- Other Japanese-built engines (where Mitsui has the closest service capability)
- Component supply for legacy engines
Service operations are an important revenue stream, particularly as Japanese shipping fleet engines come due for major overhauls.
Industry significance
Engineering continuity
The 1926 B&W relationship and 1948 Sulzer relationship represent extraordinary continuity in the marine engine industry. Both relationships have survived:
- World War II disruption
- Multiple OEM corporate restructurings (B&W → MAN B&W → MAN-ES → Everllence; Sulzer → Wartsila → WinGD)
- Multiple Mitsui corporate restructurings
- Significant evolution in engine technology (mechanical → electronic, single-fuel → dual-fuel → alternative-fuel)
This continuity reflects the fundamental stability of license-builder + design-house structure in slow-speed marine engines.
Japanese maritime industry resilience
Mitsui E&S DU’s role in maintaining Japanese marine engine production is strategically important. Japan is one of three major shipbuilding countries (alongside South Korea and China). Domestic engine production is critical to Japan’s maritime industrial policy and resilience.
Alternative-fuel transition
Mitsui E&S DU is producing alternative-fuel engines (methanol ME-LGIM, dual-fuel ME-GI, X-DF) for Japanese-built ships. The company’s continued investment in alternative-fuel production capability is essential for Japanese shipbuilders to compete in the methanol and ammonia ship orderbook.
Future outlook
Production trajectory
Annual production is expected to remain in the 140-160 large engine range, scaled to Japanese shipbuilding demand. Modest growth or contraction will follow Japanese shipyard order book trends.
Alternative-fuel investment
Capital investment in alternative-fuel engine production capability (ammonia, methanol expansion) is ongoing under both Mitsui E&S DU and Mitsui E&S Holdings strategic plans.
License relationships
Both license relationships (Everllence and WinGD) are expected to continue. There is no commercial pressure or strategic reason for the relationships to end; both OEMs benefit from a strong Japanese licensee, and Mitsui E&S DU benefits from access to both major design lines.
Service business
Service operations are likely to grow as the Japanese shipping fleet ages and engines come due for major overhauls. Service revenue typically has higher margins than new-build engine production, so growth in this segment is strategically valuable.
Related Calculators
- Engine Power Per Cylinder Calculator
- Brake Mean Effective Pressure Calculator
- Specific Fuel Oil Consumption Calculator
See also
- HHI-EMD (Hyundai Heavy Industries Engine and Machinery Division)
- Hanwha Engine Corporate History
- MAN B&W ME-C Electronic Control Overview
- WinGD Corporate History
- Burmeister & Wain History
- Sulzer Marine Diesel Engines History
References
- Mitsui E&S Press Release. FY2023 Large Marine Engine Production Volume: https://www.mes.co.jp/english/press/2024/0509_002429.html
- Mitsui E&S Press Release. 120 Million HP MAN B&W Cumulative Milestone (Nov 2024): http://www.mes.co.jp/en/news/2024/1118/
- Mitsui E&S Holdings corporate website
- Pounder, C. C. (Woodyard, D., ed.). (2020). Pounder’s Marine Diesel Engines and Gas Turbines (10th ed.). Butterworth-Heinemann.
- Tsuneishi Shipbuilding press releases on 2021 Mitsui shipyard acquisition