Traiam Dumitrache, a 50-year-old Romanian from London, was one of four pleasure fisherman in the boat when it collided with another boat about 12.30am.
Police and marine accident investigators have named the boat believed to have collided Mr Dumitrache’s vessel off Shoreham.
Police say the vessel is the scallop dredging boat, Vertrouwen, which left Shoreham around the time of the incident bound for Grimsby.
Police are now in touch with the owners, MacDuff Shellfish Ltd, who are co-operating fully with the investigation.
A Sussex Police spokesman said: “It is now known that the collision occurred around 12.30am and the boat was lost without raising a distress call.
“One man was rescued by commercial fisherman after clinging to a buoy for more than five hours and another man’s body was recovered by an HM Coastguard helicopter on Sunday morning.
“Two other men who were on board the boat are still missing.”