On June 27, the ultimate load test of the stern door for the first vessel of the Wallenius Wilhelmsen series 9300-CEU car carrier, built by China Merchants Jinling Shipyard (Jiangsu), was successfully completed. Under a full-load condition of 530 tons, the test verified the structural integrity of the stern door and achieved full compliance of all performance indicators, marking the successful completion of the load test for the world’s highest-capacity Ro-Ro ship stern door and accelerating the high-quality delivery of subsequent vessels in this series.
The stern door is the core loading and unloading hub of a car carrier, and its structural strength directly determines the vessel’s operational limits and safety baseline. This test innovatively adopted a “main ship + dual barge” linked test architecture, targeting the load characteristics of the oversized stern door, with extreme conditions serving as the design control benchmark throughout the process.
The project team systematically completed the overall scheme planning for barge load-bearing and tooling layout in the early stages, implemented specific structural reinforcement for concentrated hinge stress points, and simultaneously covered strength checks for two extreme conditions: normal wire rope load-bearing and failure. A barge surface load of 500.3 tons was set as the design upper limit. Concurrently, full-process floating state pre-calculations and tooling height adaptability assessments were completed in advance, supported by the deployment of high-precision level monitoring equipment. Risk management was comprehensively front-loaded to the test preparation phase, ensuring the scientific nature and safety of the test plan from the outset.
On-site operations strictly followed the principle of “step-by-step verification, full-process control.” After the main ship and barges were secured with multiple moorings and the support tooling was rigidly fixed, the stern door was smoothly lowered onto the barge at the specified angle. Following joint verification and sign-off by the design center, the owner, and the classification society, the loading procedure was officially initiated.
The loading process was implemented in two orderly stages: after completing the initial 300-ton ballast loading and structural strength recheck, the self-tensioning function was activated for stepwise loading in three batches, ultimately precisely reaching the target test load of 530 tons. Throughout the test, dynamic calculations of the floating states of both the main ship and barges, as well as real-time verification of tooling and hull structure, were carried out simultaneously. Complete data records were retained for each loading stage and confirmed by multiple parties, ensuring the test process was safe and controllable. The test also received strong support from the maritime authorities, with a maritime patrol boat providing full-time tracking and standby, securing the outer perimeter for waterborne operations.
After the full-load static observation period and complete unloading, comprehensive inspection revealed no structural tearing, permanent plastic deformation, or other defects in the stern door body. The overall performance fully met the specifications and design requirements.
The success of this test not only fully validated the reliability and stability of the stern door system for the 9300-CEU series vessels but also established a complete technical system for testing ultra-large load Ro-Ro equipment. This provides a replicable technical template for the construction of subsequent vessels in the same series, further consolidating Jinling Shipyard’s technical competitiveness in the field of large car carrier construction and injecting strong momentum into the upgrade of the enterprise’s high-end shipbuilding capabilities.
