Thomas Hodgson, aged 42, was last seen rowing a small dingy towards his yacht based in Brixham on September 9.
Detectives from Devon and Cornwall Police today said they had informed Mr Hodgson's family.
A search started following his disappearance including around Brixham Harbour after concerns he had fallen into the water.
A member of the public out fishing alerted police to a body in the water off nearby Breakwater Beach this morning.
A force spokesman said: "As this was in the area the last sighting had taken place there was concern that it was Mr Thomas Hodgson.
"Detectives were called to the scene after the RNLI had lifted the male from the water.
"Enquiries took place throughout the day in order to establish the males identity. Unfortunately it is now believed the male is in fact Mr Thomas Hodgson.
"His family have been informed."
Detectives are appealing for people to come forward with information over Mr Hodgson's whereabouts before he went missing.