The next hacker playground: the open seas - and the oil tankers and container vessels that ship 90 percent of the goods moved around the planet. In this internet age, as more devices are hooked up online, so they become more vulnerable to attack. As industries like maritime and energy connect ships, containers and rigs to computer networks, they expose weaknesses that hackers can exploit. Hackers recently shut down a floating oil rig by tilting it, while another rig was so riddled with computer malware that it took 19 days to make it seaworthy again…