HOUSTON (May 19, 2005)- A boat crew from Coast Guard Marine Safety Office Houston escorts a tug and barge during a maritime security patrol in the Houston Ship Channel. The Port of Houston is the second largest petrochemical complex in the world. Over 35% of all U.S. gasoline is refined here. 7,600 deep draft vessels arrive each year - 60% oil/chemical and 40% freight. Approximately 700 ships transit the Houston-Galveston Ship Channel each day.