The Marine Casualty Investigation Board has found that the Rising Sun lobster boat sank because it was overloaded and unstable.
The boat's 37-year-old skipper Pat Colfer and 46-year-old crewman Jimmy Meyler drowned when the trawler went down off Kilmore Quay in November 2005.
Diver Billy O'Connor, 49, died during an underwater search of the vessel two days later. The report does not deal with his death.
The board said the capsize and sinking of the boat was due to a combination of factors such as overloading due to heavy winch machinery, nets, trawling equipment, a large number of pots, and the catch, which reduced the vessel's freeboard.
It said the vessel had a very poor stability profile at the time and that the crew did not detect water leaking into the machinery space as the bilge alarm had been disconnected.
The report added that alterations had been made and its use changed, which resulted in a potentially hazardous stability condition existing.
In a comment on the report, the Colfer family challenged the statement about the bilge alarm and said it believes that when the boat capsized something fell on the connections and disconnected them.
