Mark Stribling, 35, and Robert Stilwell, 33, tried to get the 16 adults and two children across the English Channel from France in a rigid inflatable Boat on the evening of May 28.
The boat broke down, losing all power, and everyone on board needed to be rescued by the Coastguard and the crew of HMC Valiant.
Each of the migrants had paid £6,000 for the crossing - and Stribling and Stilwell were expecting to pocket £2,000 each from the deal.
They were sentenced at Maidstone Crown Court and will both serve at least four years each behind bars.
The court heard that the two men, who both had criminal records, had been wearing all-weather clothing and life jackets on board.
The vessel lost power shortly after setting off from France and was drifting for almost three hours, taking in water.
A video from the search and rescue helicopter played to the court showed a migrant using a small container to try to bail out the boat.
Stribling could be seen remonstrating with other migrants.
The woman migrant was "showing signs of hypothermia" when lifeboat crews arrived, prosecutor Nina Ellin said.
It took four return trips to the HMC Valiant, a Border Force cutter ship, to remove all the migrants and the defendants, the court was told.
Ms Ellin said rescuers overheard one of the defendants - the only English speakers on board - claim they had been fishing and had rescued the migrants.
Once the pair arrived back at Dover, they appeared in "good spirits" and joked about the strength of the tea and coffee.
The husband of the woman migrant told police he had been told by another migrant that there had been threats "the boat would be punctured" with scissors if they alerted authorities.
The woman said she had been told of threats they would be "thrown into the sea".
The pair feared for their lives, and Ms Ellin said: "They believe if they had been 10 more minutes on that boat they would have died."
The Coastguard was only alerted because of phone calls the migrants made to family members.
In a separate case, Stephen Jackson, 51, has been jailed at Lewes Crown Court for four years and nine months after pleading guilty to attempting to smuggle 17 immigrants into Chichester Marina in May.