The chief engineer got 30 years, and 13 other crew members were sentenced to up to 20 years in prison, Yonhap news agency and other South Korean media reported, citing the Gwangju District Court in southern South Korea.
Captain Lee Joon-seok and three other key crew members were earlier indicted by prosecutors on homicide and other charges. Eleven others faced less serious charges.
The widely vilified Lee could have received a death sentence for the homicide charges. South Korea hasn't executed anyone since late 1997, though its courts occasionally issue the punishment.
Prosecutors and the crew members have one week to appeal, according to the court.
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Court officials didn't immediately answer calls seeking confirmation.
The 15 crew members tasked with navigating the ferry Sewol have faced scathing public criticism because they escaped the sinking ship while many of their passengers were still trapped inside. A total of 476 people were aboard the ship and only 172 were rescued. Most of the dead were teenage students traveling to a resort island on a school trip.