Finland-based ship power supplier Wartsila Corp said it would double its production capacity of fixed pitch propellers in the city of Zhengjiang, Jiangsu province, the Yangzi Wanbao reported. The propeller is commonly used in container ships. The Finnish company established a joint venture with the China State Shipbuilding Corporation in 2004, called Wartsila-CME Zhenjiang Propeller Co Ltd, to design and build propellers for gigantic vessels such as oil tankers and cargo containers. Chinese companies have built 425 ships in the first five months of this year, 45% of which have been for overseas orders.