text:  The building of the Ship Channel also followed the Spindletop Oil Discovery about 80 miles east of Houston, paving the way for the city to become an energy capital. Today, roughly 70% of what is imported and exported through the Ship Channel is petroleum products. Upstairs, Ashley Williams introduces me to the two captains of the Sam Houston, Genaro Ambriz and Greg Penton. Penton, who is steering, uses the radio to talk with an approaching barge.