Boater Gary Hedges died after falling into the Kennet and Avon Canal in Devizes, an inquest heard.
Wiltshire Coroner David Ridley said he did not know why Mr Hedges fell in, but ruled that he suffered an adverse reaction to being in the water, causing a cardiac arrest which led to his death.
The inquest at Salisbury on Friday heard Mr Hedges, 53, lived on a narrowboat called Gold Crest after he left his wife in August 2012. At the time of his death he was looking after a boat called the Spirit of Marmalade.
Another boater, Stephen Povey, knew Mr Hedges and saw him on the day he died, October 9 last year.
In a statement he said he asked Mr Hedges how he was and he replied he was fine. Later on that day, at 2.45pm, he saw the Spirit of Marmalade coming back past his boat to the mooring at Kingsmanor Wharf.
Kingsmanor Wharf resident Louis Rutter saw that the rear of the Spirit of Marmalade was tethered to a mooring but the front end was not. He then saw Mr Hedges’ body floating in the canal.
Police found no suspicious circumstances and a post mortem examination found no evidence of third party involvement.
Mr Hedges’s estranged wife, Deborah who lives in Pewsey, said in a statement that her husband had suffered fits through drinking too much alcohol. She said he worked for Sally Boats as a technician but was dismissed due to alcohol issues.
Mr Hedges had been seen by the Lansdowne Surgery in Devizes a month before his death and had been prescribed medication for alcohol withdrawal symptoms. His alcohol intake was ten cans of lager a day. He also smoked cannabis.
Salisbury District Hospital consultant Dr Susan Burrows said Mr Hedges was not intoxicated at the time of his death and said there were no injuries on his body. His lungs were waterlogged and she said it was possible that when Mr Hedges entered the water he could have suffered a reflex cardiac arrest.
Mr Ridley recorded a verdict of accidental death, saying it happened due to submersion in water rather than drowning.