South Korean shipyards have been grabbing orders by virtue of low prices since last year. In this context, Chinese peers have been losing their long-time price advantage, dragged by the weight of their empty vessels.

Generally speaking, the difference in lightweight between the two countries ranges from 5 percent to 10 percent. If the total lightweight reduces by 5 percent, Chinese shipyards can cut back on the costs of materials and processing by as high as CNY5 billion annually, according to an analysis. It is worth noting that they recorded less than CNY5 billion in operating profit last year.

Why Chinese shipyards cannot reduce the lightship weight? To answer this question, we need to see the practices of their South Korean counterparts first. The latters constantly optimize a ship's structure, which has become a routine of their designers. For example, Daewoo Shipbuilding & Marine Engineering, one of Korea's top three yards, set a goal in 2004 of a 10 percent reduction in VLCC's structural weight and a 20 percent decrease in the number of structural parts. What's more, at the end of 2016, the shipbuilding giant made a further improvement, and a VLCC's lightweight dropped by a further 2 percent.

The two major reasons of the failure of Chinese shipyards to realize a better lightweight are as follows. Firstly, the design capability is basically in the hands of design institutes which lacks the full knowledge of shipbuilders' production characteristics. Secondly, shipyards have not enough experience in structural optimization. Therefore, it is advisable for them to collaborate with their overseas peers to improve the capabilities amid climbing prices of raw materials.