The third day of search efforts drew to a close on Thursday with no major updates and failed to locate Mr Higgins, 57, or his vessel.

Air crews had returned to waters off the Murray Mouth in the morning with police officers combing the beach for debris between the Coorong and Goolwa.

The Police Operations Unit also returned to waters around Granite Island while planes and a police helicopter were unable to be used because of bad weather.

The search has covered about 500 square kilometres, from Encounter Bay to Cape Jaffa.

Debris and items belonging to Mr Higgins including his wallet and keys were located yesterday, several kilometres from the Murray Mouth.

The search for Mr Higgins has included the assistance of Sea Rescue volunteers, the police helicopter (PolAir) and planes and a Challenger aircraft provided by AMSA (Australian Maritime Safety Authority) using infrared radar equipment.

Search and rescue efforts began on Tuesday when police received a distress call at about 5am.

Mr Higgins was reportedly knee-deep in water aboard his vessel which had been anchored off Granite Island.

Operations Inspector of Hills Fleurieu Local Service Area Gus Sickerdick said it was unclear whether Mr Higgins had deliberately set sail or been blown from moorings in rough conditions.

"We are still investigating the circumstances and what has gone wrong," he said.

"Our patrols have searched from the Mouth to the Goolwa Beach Surf Rescue Club and have found pieces of debris which will form part of the investigation."

The search came less than two weeks after Mr Higgins and his crewmate Derek Robinson were rescued after spending more than four days missing at sea, in the state's biggest-ever sea rescue operation which covered more than 104,000 square kilometres.

The pair were found at Salt Creek before being towed to Victor Harbor, where Mr Higgins had remained anchored since.

He and the Margrel were last spotted about 3pm on Monday, anchored off Granite Island, when a weather warning was declared for the region.

Mr Robinson yesterday revealed Mr Higgins had been the victim of ongoing abuse while moored in Victor Harbor.