🌊 A "moving giant island" has appeared off the coast of Kyoto, Japan. With four legs extending over 100 meters to the seafloor, it lifts its entire hull above the waves. Built at a cost of approximately $3.3 billion yen (roughly $330 million USD), Shimizu Corporation's "BLUE WIND" is one of the world's largest SEP vessels, poised to transform Japan's offshore wind energy future. Here's an inside look at this engineering marvel and its role in Japan's energy transition.
What is a SEP Vessel: Ships That "Stand" on the Ocean
SEP vessels (Self-Elevating Platforms) are specialized ships unlike any conventional watercraft. They feature four massive legs that extend to the seafloor, using hydraulic jacks to lift the entire hull above sea level.
This unique design provides critical advantages for offshore construction. By eliminating wave-induced motion entirely, SEP vessels enable precision work that would be impossible on standard ships. Installing offshore wind turbines requires millimeter-level accuracy—a feat achievable only when the work platform is rock-solid.
The stable platform also allows these vessels to carry massive cranes. Lifting heavy loads from an unstable ship risks crane tipping. With the hull fixed to the seabed, SEP vessels can safely hoist components weighing thousands of tons.
BLUE WIND: World-Class Specifications
Completed in January 2023, "BLUE WIND" represents Shimizu Corporation's approximately ¥50 billion ($330 million) investment in offshore wind construction capability. Japan Marine United (JMU) built the vessel at its Kure shipyard.
The specifications are remarkable. At 142 meters long and 50 meters wide, the vessel displaces approximately 28,000 gross tons. Its legs extend 90 meters (maximum 109 meters), enabling operations in water depths of 10 to 50 meters.
The main crane boasts a maximum lifting capacity of 2,500 tons—the largest among Japanese SEP vessels. For comparison, Penta-Ocean Construction's "CP-8001" handles 800 tons, Obayashi/TOA's "Hakkaku" manages 1,250 tons, and the Penta-Ocean/Kajima/Yorigami "CP-16001" lifts 1,600 tons. BLUE WIND stands in a class of its own.
Maximum hook height reaches 158.5 meters (at 1,250-ton capacity), accommodating today's largest commercial turbines at 15MW. The design even anticipates GE Vernova's announced 18MW turbines.
Critically, BLUE WIND is "self-propelled." Cruising at 11 knots (approximately 20 km/h), it eliminates the need for tugboats, significantly reducing project timelines.
Proven Track Record: Four Projects Completed
Since becoming operational in 2023, BLUE WIND has steadily built its portfolio across Japan and Asia.
Its maiden project was the Nyuzen Offshore Wind Farm off Toyama Prefecture, installing three 3MW turbines. Completed in September 2023, this facility marked Japan's first privately-funded fixed-bottom offshore wind farm in general sea areas.
Next came the Ishikari Bay New Port Offshore Wind Farm in Hokkaido. BLUE WIND assembled all 14 units of 8MW turbines, creating Japan's largest offshore wind facility at 112MW capacity (approximately 99MW grid connection). Despite typhoons and torrential rain, the crew maintained millimeter-level precision throughout.
Internationally, BLUE WIND has contributed to Taiwan's offshore wind expansion. At the Yunlin Offshore Wind Farm, it installed monopiles for all 80 units of 8MW turbines, completing work in July 2024. The vessel has also been deployed to the Hai Long Offshore Wind Project.
Japan's Offshore Wind Ambitions
In December 2020, Japan's government set ambitious targets: 10GW by 2030 and 30-45GW by 2040. With cumulative installed capacity at approximately 42MW as of 2024, rapid expansion lies ahead.
The 2019 "Act on Promoting Utilization of Sea Areas for Renewable Energy Power Generation" established a framework for general sea area projects. Round 1 selected sites off Akita Prefecture are currently under construction, with operations scheduled for 2026.
Round 2 projects, including areas off Akita's Oga, Katagami, and Akita cities, plan to install 15-18MW class turbines. Shimizu's Vice President Takeshi Sekiguchi notes: "The turbine sizes that match BLUE WIND's capabilities arrived faster than we expected."
Construction in general sea areas is expected to accelerate from fiscal 2027. Penta-Ocean Construction has announced plans for a massive Heavy Lift Vessel with 5,000-ton crane capacity, signaling industry-wide preparation for growth.
Significance of the Kyoto Port Call
In January 2026, BLUE WIND arrived at JMU's Maizuru shipyard in Kyoto Prefecture for maintenance. Having entered port on January 6th, the vessel's towering presence is visible from Maizuru's city center.
Maizuru City's official social media encouraged residents: "Please experience its overwhelming presence!" Regular maintenance in Japan's shipyards ensures the vessel maintains peak performance for demanding offshore operations.
BLUE WIND has designated Muroran Port in Hokkaido as its home base, strategically positioned for ongoing and future offshore wind projects in northern Japan.
Building a Domestic Supply Chain
JMU, a major Japanese shipbuilder, constructed BLUE WIND. Shimizu Corporation insisted on domestic manufacturing, prioritizing the development of Japan's offshore wind supply chain.
Currently, four major SEP vessels operate in Japan: Penta-Ocean's "CP-8001" and "CP-16001," Obayashi/TOA's "Hakkaku," and BLUE WIND. This fleet forms the backbone of Japan's offshore wind construction capacity.
Further expansion is underway. Penta-Ocean Construction and Fuyo General Lease have announced a ¥120 billion ($800 million) investment in a 5,000-ton capacity Heavy Lift Vessel, scheduled for delivery in March 2028.
Challenges Ahead: Costs and Human Capital
Significant challenges remain. Rising material and labor costs have triggered project cancellations and reductions across Europe and the United States. Mitsubishi Corporation recorded ¥52.2 billion in impairment losses on three offshore wind projects off Akita.
Motoshi Igari of the Floating Offshore Wind Technology Research Association points to a critical gap: "Unfortunately, Japan lacks sufficient personnel to support offshore wind development." Installing large turbines requires specialized skills and experience, making human capital development an urgent priority.
Despite these hurdles, offshore wind remains central to Japan's 2050 carbon neutrality goals. Vessels like BLUE WIND represent essential infrastructure for achieving this vision.
Japan is expanding its offshore wind capacity with world-class SEP vessels like BLUE WIND. What technologies or vessels does your country use for offshore wind development? Is offshore wind a significant part of your nation's renewable energy strategy? We'd love to hear your perspective and experiences.
References
- https://trafficnews.jp/post/629081
- https://www.shimz.co.jp/company/about/news-release/2022/2022046.html
- https://www.shimz.co.jp/sep/
- https://www.jmuc.co.jp/news/2023/01/bluewind.php
- https://www.enecho.meti.go.jp/about/special/johoteikyo/yojohuryokuhatuden2025.html
- https://www.penta-ocean.co.jp/news/2025/250127-1.html
Reactions in Japan
I can see it from near my house, and it's so huge I didn't know what it was at first. Can't believe that's a ship. Took my kid to see it and they were super excited.
The importance of maintaining and developing SEP vessel technology domestically. Wind turbine makers were overtaken by foreign competitors, but Japanese firms are holding strong in construction vessels. The ¥50 billion investment in BLUE WIND was a bold decision.
Watched a video of it extending its legs and rising above the sea surface—such a surreal sight. Looks like CGI. Hard to believe such a ship actually exists.
They say ¥50 billion, but I wonder if Japan's offshore wind will really be profitable. With all the withdrawals in Europe and the US, won't it just end up subsidized by taxes?
Impressive that Shimizu can make such bold investments. Building a track record in Taiwan too, growing presence in the Asian market. Seeing the strength of Japanese companies.
With the 2030 target at 10GW and current installed capacity at 42MW, that's about 0.4% achievement. SEP vessels are ready, but the projects themselves are way behind schedule. Time to revise targets?
Shot this in Maizuru! The silhouette against the sunset is incredible. I wish industrial heritage landscapes like this got more attention.
I support offshore wind in principle, but proper coordination with fishing grounds is essential. Impact during construction, coexistence after operation—please listen to local voices.
Looking at this industry for job hunting—SEP vessel operators need serious expertise. They say there's a talent shortage, but I'm curious about compensation and training environments.
Honestly, many wind turbines are Chinese-made, so what's the point of only having domestic transport vessels? Unless we control the upstream supply chain, we'll lose anyway.
Fascinating from a historical perspective that Japan, once a shipbuilding powerhouse, is showing presence in SEP vessels, a new ship category. Worth noting as a form of shipbuilding technology inheritance and development.
When they said Kyoto, I thought city center, but it's Maizuru. Attention on Sea of Japan side ports like this could boost regional development. Could it become a tourist attraction?
Checked Shimizu's stock price—offshore wind contribution seems limited still. But long-term potential exists. Penta-Ocean also announced ¥120 billion investment. The offshore wind competition among general contractors is heating up.
I support renewable expansion, but are environmental assessments for offshore wind being done properly? Marine ecosystem impacts should be considered. Can't just prioritize construction.
A colleague was involved in building BLUE WIND at JMU—said it was technically quite challenging. But the sense of achievement when completed was incredible. It's a crystallization of Japanese shipbuilding technology.
As a Dane, it's great to see Japan seriously entering offshore wind. But with our 25+ years of North Sea experience, I think progress could be more efficient. There's plenty of room for collaboration.
Saw BLUE WIND operate in Taiwan firsthand. The precision and efficiency are real. Japanese construction tech is reliable. Our Yunlin project finished on schedule.
In Scotland, floating offshore wind is becoming mainstream. Japan has lots of deep waters too, so shouldn't they consider investing in floating systems, not just fixed-bottom? SEP vessels alone might not be enough.
Korea is also pushing offshore wind, but honestly surprised by Japan's speed in SEP vessel development. We have a 20GW target by 2030, but construction infrastructure isn't keeping up. Something to learn from.
Glad to hear Dutch SEP design company GustoMSC was involved in Japan's CP-16001. Offshore wind really requires global cooperation. No single country can do it alone.
Offshore wind projects are advancing on the US East Coast, but some developers are withdrawing due to cost overruns. Hope Japan doesn't repeat the same mistakes. Government support mechanisms are crucial.
Vietnam has huge offshore wind potential but no construction vessels. If Japanese SEP vessels expand in Asia, please come to Vietnam too. Southeast Asian market is promising.
In Germany, offshore wind is a key pillar of power supply. With Japan's earthquake risk, I'm curious about seismic design for monopile foundations. That's where Japanese engineering could shine.
France is also a latecomer to offshore wind, but I've never heard of a ¥50 billion investment like BLUE WIND. Impressed by Japanese construction companies' risk-taking ability. Is there government backing?
Honestly, I think offshore wind is overrated. Maintenance costs are high, and capacity factors can be lower than onshore wind. Shouldn't Japan focus on nuclear restarts instead?
Norway is shifting from oil/gas to offshore wind, and that know-how is paying off. Japan has shipbuilding expertise, so they should excel in floating wind too. Looking forward to it.
Victoria state in Australia is also advancing offshore wind plans. Would love Japanese SEP vessels to come here too. Currently we have no choice but to rely on European vessels.
There are offshore wind plans in the Gulf of Mexico too. Japan and Mexico have deep ties in the auto industry, so energy cooperation would be great. SEP vessels are globally scarce.
As a Japanese American, it's proud to see Japanese tech going global. But in the US, the Jones Act (requiring US-flagged vessels) makes direct entry of Japanese ships difficult.
Greece is a shipping powerhouse but owns zero SEP vessels. Japan's ability to build and operate domestically is a strength. Momentum for offshore wind is growing in the Mediterranean too—maybe we'll see them here someday.