The drowning deaths of two fishermen have prompted the Deputy Coroner to recommend crew aboard commercial fishing boats wear life jackets which can inflate automatically.

Adam Nicolai and Justin Hellyer died when a fishing boat sank off Stansbury on Yorke Peninsula in September 2008.

The men had been fishing with their friend and skipper of the boat, Andrew Pisani, when two big waves swamped the vessel during a squall.

The court was told the men were not wearing life jackets and all three tried to swim to safety but only Mr Pisani survived.

Deputy Coroner Anthony Schapel said the boat was unregistered and would not have been regarded as seaworthy for the conditions.

He recommended the Transport Minister make it a legal requirement for self-inflating flotation devices to be worn at all times by crews on commercial boats.

Mr Pisani's company previously was fined in the Industrial Court.