The three men were arrested last Thursday a few kilometres (miles) from the coast near the village of Wimereux in northern France after a tip-off from
British authorities, local newspaper la Voix du Nord reported.
The retired naval captain, Ronald Scott, was sentenced to 30 months and given a 10-year ban from French territory on Monday, while the other two were
given sentences of one and two years respectively, the local prosecutors' office in Boulogne-sur-Mer told AFP.
Each migrant had paid 9,000 euros ($10,500) for the short trip from the French coast to Britain, the prosecutor said.
France's northern coast remains a magnet for migrants looking to cross the Channel, with police and the coast guard fighting a constant battle against people smugglers.
It's not the first time British people smugglers have bee jailed in France for attempting to ferry migrants across the Channel.
In July 2017 a French court jailed two Britons for over two years for having smuggled migrants to England in a light aircraft in what prosecutors said was a first.