ExxonMobil continues to use single-hulled oil tankers despite growing condemnation of their use, and despite the fact that their competition have almost all switched to double-hulled vessels.  Double-hulled vessels are deemed safer and more effective in preventing oil spills. 

The Age: "Even after 79 per cent of the world supertanker fleet has been replaced by craft with two hulls, Exxon Mobil remains the biggest Western user of the older designs. It hired more of the tankers last year than the rest of the 10 biggest companies combined.

Exxon, the world's largest oil company, has kept using tankers with one hull even as 151 countries have decided two are better than one for preventing oil spills and pledged to ban single-hull vessels by 2015. The European Union called the design more accident-prone in 2003, when it started a prohibition that takes full effect next year. London-based BP says it won't hire them because of the risk of leaking.

US refining rivals, including Sunoco, Chevron, ConocoPhillips and Koch Industries, and Paris-based Total didn't hire one such vessel last year. Exxon's use of single-hull ships compared with its nine biggest competitors is based on more than 12,500 ship rental deals."