On 30 April 2025, the self-propelled, self-elevating offshore wind turbine installation platform “Zhengli 3500”, independently built by Shanghai Zhenhua Heavy Industry Co., Ltd. (ZPMC), was successfully launched in Nantong, Jiangsu using Evergreen marine airbags. The platform, with a lightship weight of 30,500 tons, has now set a new world record for the heaviest vessel ever launched using the marine-airbag method.
“Zhengli 3500” measures 143.8 m in length, 56.6 m in breadth, and 13 m in depth. It is equipped with a 3,500-ton twin-main-hook revolving crane, featuring a main hook lifting height of 160 m and an auxiliary hook height of 180 m—performance parameters that place it among the most advanced in its class. After launch, the vessel achieved a forward and aft draft of 5.0 m.
Full Technical Involvement from Design Stage to Final Launch
As a global leader in marine airbag manufacturing and vessel-launch engineering,
QINGDAO EVERGREEN MARITIME played a critical role throughout the entire process:
Signing a technical consultancy contract for the airbag launch
Supplying 82 ultra-high-strength, high-pressure marine airbags
Providing complete engineering services for the final launch operation
EVERGREEN’s engineering team collaborated closely with ZPMC to ensure a safe, smooth, and precisely controlled launch under challenging conditions.
Key Technical Challenges of This Launch
1. Conversion of the Existing Slipway
The original slipway was designed for skid-based launching:
200 m in length, 80 m in width, and a slope ratio of 20.5:1, featuring four skids (1.2 m wide, 0.8 m high).
To adapt it for marine-airbag launching, EVERGREEN engineered a full modification:
Filling gaps between the skids with concrete blocks and crushed stones
Leveling and compacting the surface with sand
Converting the slipway into a smooth inclined plane suitable for airbag deployment
2. Complex Hull Structure
As a jack-up installation platform, the vessel features four spud cans extending 50 cm below the hull bottom, along with a slender bow section.
Both characteristics significantly increased the difficulty of airbag positioning, force distribution, and launch stability.
3. Insufficient Water Depth at Launch
Limited water depth demanded precise control of vessel trim, airbag release sequence, and launch velocity, leaving minimal margin for error.
Despite these challenges, EVERGREEN’s engineering team conducted detailed modeling, load analysis, and risk evaluations, optimizing every aspect of the launch conditions. The super high-pressure marine airbags supplied by EVERGREEN featured a safety factor exceeding 8, substantially enhancing overall safety and redundancy for this heavy-lift operation.
A Breakthrough for the Global Marine-Airbag Industry
The successful launch of the 30,500-ton “Zhengli 3500” marks a major milestone in the evolution of marine-airbag technology and sets a new benchmark for the global shipbuilding industry.
The rapid development of this technology is driven not only by China’s booming shipbuilding industry, but also by decades of dedication from generations of marine-airbag specialists. China pioneered the development of marine airbags and the airbag-launching method, and continues to promote their application worldwide—offering an innovative and efficient solution for modern shipbuilding and offshore engineering.
QINGDAO EVERGREEN MARITIME remains committed to advancing marine-airbag technology and delivering safe, reliable, and cost-effective engineering solutions to clients around the world.