On December 24, 2018, the world’s first 85000m3 very-large ethane and ethylene carrier, which was built by the Offshore Engineering Company of DSIC for JHW Company, came back from a successful sea trial lasting for 5 days. This indicates that DSIC has overcome the technological difficulties in terms of key design and construction for very-large ethane and ethylene gas carrier, and has realized the transformation, which has won high recognition in the industry of liquefied gas carrier building. The ship adopts the dual-fuel and low-speed main engine to directly drive the adjustable-pitch propeller, and has created a number of the world’s “Firsts”, including the world’s first C-Type tank gas carrier with stowage reaching 85000m3; the world’s first C-Type tank with the largest unit volume; and the first dual-fuel (ethane and diesel) and low-speed main engine designed by MAN patent and so on. Since the commencement of the construction, DSIC carried out careful organization to overcome the difficulties, completed production and technology arrangements based on the characteristics of the ship type, and prepared thorough construction processes to prompt the task steadily. During the trial, all the project personnel controlled the progress of the trial dynamically and upgraded the plan timely according to the outline, and successfully completed the task with all the performance indexes reaching the expected goal.