"The only person on any vessel who knows the exact cargo safety limit, excluding ballast water, fuel, passengers and others, is the first mate," the official said.
All 15 surviving crew members involved in the ferry's navigation have been arrested, accused of negligence and failing to protect passengers. Prosecutors also detained three employees of the ferry owner who handled cargo, and have raided the offices of the ship owner, the shipping association and the register. Heads of the shipping association and the register offered to resign in the wake of the disaster.
The cause of the sinking remains under investigation, but experts have said that if the ship were severely overloaded, even a small turn could cause it to lose its balance. Tracking data show the ship made a 45-degree turn around the time it began sinking; crew members have reportedly said that something went wrong with the steering as they attempted a much less severe turn.
Some experts say the Seoul never should have been cleared to operate after last year's redesign because the owner would not be able to make money under the register's new cargo limits.
The ferry operator "was trying to make a profit by overloading cargos," said Kim Gil-soo, a professor at Korea Maritime and Ocean University in Busan, "and public agencies that should have monitored did not monitor that."
According to South Korean law, the association may report violations to either the coast guard or the state-run port operator, but both entities said they were never told of excessive cargo on the Sewol. The shipping association has refused to say how often it has reported violations.
A coast guard official said the shipping association should have reported any excessive cargo to the operator of Incheon port, where the Sewol last departed. An official with the port operator says it is the coast guard that should have been alerted. The coast guard official spoke on condition of anonymity, saying he was not authorized to speak about matters under investigation; the port official refused to provide his name.
South Korea, unlike many other countries, relies on a private industry-affiliated body to determine whether a ship is safe to sail. The shipping association, whose members are shipping companies and ship operators, took on that responsibility in 1973, following a 1970 sinking in which about 320 people died.
