Captain Jasprit Chawla was sentenced to 18 months in prison and fined $14,000, while chief officer Syam Chetan was sentenced to eight months and fined $7,000 on Wednesday.
The 270,000–dwt single-hulled tanker (built 1993), owned by China’s Hosco, was hit by a Samsung Heavy Industries crane barge while at anchor in the Yellow Sea in December 2007, spilling 10,500 tonnes of crude and causing at least $500m in damages to a wide stretch of coastline.
Hosco was fined $21,000.
The South Korean appeal court overturned a lower court ruling which found the operators of the VLCC not guilty and placed the blame almost entirely with Samsung.
The ruling is sure to prompt widespread anger among shipowners and crew unions.
The barge broke free from two tugs in rough seas and smashed into the tanker, which could not avoid it. The court jailed one tug captain for two years and six months, while the other was jailed for eight months.
Hosco said their crew acted with the utmost professionalism to slacken the anchor line and move the massive tanker at short notice to minimise the collision.
But the court said: "The captain could have averted a collision by pulling up the anchor or moving backward at full or half the usual speed."