SAN ANTONIO - SeaWorld Entertainment Inc. announced plans Monday to build an $18 million roller coaster at its San Antonio park as the company attempts to chart a new course following years of public backlash over its treatment of killer whales. The Orlando, Fla.-based theme park chain is trying to repair its public image - damaged by the 2013 documentary film "Blackfish" that criticized the company's treatment of killer whales - by plugging capital investment dollars into its parks to create new rides and attractions, retooling its mammal shows with a more educational bent, and emphasizing its animal rescue efforts.