Edward Tron, 51, from Gateshead, and Mark Quilliam, 55, from Liverpool, used their positions to smuggle cocaine into Hull from Rotterdam, their trial heard.
Tron, a steward, and Quilliam, a chef, made up to Â£60,000 a trip over a six-year-period, Hull Crown Court was told.
Tron's wife, Susan, 54, was imprisoned for nine months, after being convicted of money laundering.
The two men, who were both found guilty of conspiracy to import cocaine, were caught after the National Crime Agency (NCA) mounted an undercover operation with Dutch police.
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The Trons were found to have deposited more than Â£138,000 in their own bank accounts but could not explain where the money came from.
The smuggling enterprise was discovered after a crewmate was arrested with a large amount of cash and was later jailed for money laundering.
An NCA officer was placed on the ferry and recorded conversations in which the prosecution said Tron admitted importing drugs.
In a police interview, Tron claimed he had suspicions about the undercover police officer "within a few days", but played along by making up stories.
Two P&O ferry workers who conspired to smuggle cocaine into the UK have been jailed for 16 years each.