A fishing boat that capsized resulting in the deaths of two crew members had been modified with amateurish work, an Adelaide coroner has been told.
Transport department naval architect, Howard Peachey, also said the stability of the boat was "less than optimum" after the owner had installed a net reel at the rear of the 6.4-metre vessel.
He was giving evidence on Monday at the inquest into the drowning deaths of Adam Mark Nicolai, 28, and his friend Justin Shane Hellyer, 28, in September 2008, off the coast of Stansbury on Yorke Peninsula.
Mr Nicolai was a passionate fisherman, in contrast to his friend, who was also a poor swimmer and feared sharks.
Counsel assisting the inquest, Amy Cacas, said the men were at best "very casual employees" of fisherman Andrew Pisani, then 34, who owned the vessel.
On the evening of September 28, the three men had been pulling in a net when a swell caused the boat to roll suddenly before a large wave hit and the vessel took water.
After they were flung from the boat, Mr Pisani swam for help, but searchers only found Mr Nicolai's body.
As Mr Hellyer's body was never recovered, it was not known whether he had been wearing a lifejacket. The other two were not wearing lifejackets.
Lifejackets found on the vessel were in poor condition, Ms Cacas said.
The main issues for the coroner were the seaworthiness of the vessel, including the effect of the net reel installed by Mr Pisani, and the condition and presence of lifejackets, she said.
Mr Peachey told the inquest modifications to the vessel had been "poorly done in an amateurish manner".
Household wires were used instead of marine wire, while fibreglass work on the boat "did not look very professional to me"," he added.
Ms Pisani pleaded guilty in the Industrial Court in 2011 to failing to ensure the safety of his employees.
He later paid a total of $20,000 compensation to the dead men's families, as well as $20,000 into a trust fund for Mr Nicolai's two children.
The inquest continues before Deputy State Coroner Arthur Schapel.