PIE RCING THE DRRHNESS

摘要

The history of dedicated seawater ballast tanks (SWBT) revolves around the need for a ship to be able to perform in any given sea state when she is not laden. The development of SWBT is linked to the development of the concept of the double bottom and was driven hy the economic need to replace solid ballast systems used before the 1860s. The John Bowes, built in 1852, was the first screw collier in which temporary appliances for carrying ballast water were adopted, and the comparativ'e success of these led to the building of SS Samuel Lungin 1854. These were iron tanks made to form and fitted to the bottom of the vessel. Immediately following this, SS Rouen was built and fitted with an inner bottom, entering into the structural arrangement of the vessel similar in principle to the double bottoms of modern ships.