 The principal work of the Society's expert technical staff is to undertake surveys to ensure that the rules which it has developed, are applied to both newly built and existing ships in order to ensure the safety of these vessels.The rules cover not only hull structures, but also safety equipment, cargo handling gear, engines, machinery, and electrical and electronic systems among others.By the end of December 2007, the Society had 6793 ships totaling 152.22 million gross tons under class.