Emergency crews are counting on celestial forces to help free one of the world’s biggest container ships, which has been stuck in the River Elbe since running aground as it approached the port of Hamburg last week. After several failed attempts to budge the 400-meter (1,312 feet) CSCL Indian Ocean, owned by China Shipping Group Co., thirteen tugboats will be deployed to pull the vessel during a spring tide at about 4 a.m. on Tuesday, when the Earth aligns with the Sun and the Moon, boosting the water level by 1.2 meters above the average. It’s the first time a ship of this size has become stranded in the German waterway, which is a major import and export hub for Europe’s largest economy. With a capacity of 19,100 20-foot boxes, or TEU, CSCL Indian Ocean is among the largest container vessels operated on the world’s oceans today. The ship is currently carrying 11,800 standard boxes, mostly holding cargo such as shoes and chemicals from China and Malaysia. About 4,800 of the containers are destined for Hamburg, according to the owner. “The salvage company is very optimistic they will manage to free the vessel,” Henrik Hencke, operations manager at China Shipping’s local unit, said by phone. An electronic failure of the rudder system prompted local navigation services to steer the container ship to safe ground on Feb. 3, he said. CSCL Indian Ocean and its five sister vessels have called at Hamburg port about 60 times since the start of last year, according to Hencke. Emergency crews pumped all the heavy fuel oil out of vessel over the weekend and continue to remove ballast water and dredge the river bed around the vessel’s hull to ease the refloating attempt, Michael Friedrich, spokesman at Central Command for Maritime Emergencies Germany, said by phone.