The gory incident took place when the boat, travelling on Kharasrota river, reached mid stream at Ranapur village and the man's elder brother hit him suddenly with a dagger. His nephews too aided their father in attacking him, the police said.
Aniruddha Rana (50), a potter by profession, was travelling to a nearby market along with 15 others, including his elder brother Ananda Chandra (55) and two nephews Amulya Kumar (27) and Ajaya Kumar (13) in the boat.
The villagers kept the three attackers confined near the river bank and handed them over to the police, who arrested them.
Later they were produced before a local court, which sent the father and the elder son to jail custody and the minor son the juvenile reform home at Berhampur.
