Jeffrey Donald Crowden, 22, disappeared in 1990 after fishing on the West Coast.

He was never found.

An inquest was held in 1991 at Queenstown.

The coroner at the time, Barry Waller, made a finding that Mr Crowden, of Kettering, was dead.

"Unfortunately, the finding was attended by significant error, so much so that on March 23, 1992, the late Justice (William) Zeeman, of the Supreme Court of Tasmania, quashed the finding on the basis there was no evidence (at all) produced to the coroner to support the finding he made that Mr Crowden was dead," modern-day coroner Simon Cooper said in findings from his own re-investigation of Mr Crowden's death, which were released on Friday.

"Given the absence of evidence as to Mr Crowden's death, a fundamental jurisdictional fact to Mr Waller exercising his jurisdiction as coroner did not exist.

"Accordingly, Justice Zeeman, as well as quashing the finding, ordered that another inquest be held.

"Regrettably and inexcusably, the Coronial Court in 1992 failed to comply with that order of the Supreme Court."

Mr Cooper said it had been impossible for him to determine why.

"Mr Crowden's parents were never told that any of this had happened," Mr Cooper said.

"That this was so is a disgrace."

Mr Cooper said the omission only came to light early last year.

"Since then, a number of steps have been taken by a number of people to attempt to bring the coronial investigation into Mr Crowden's death to a proper legal conclusion," he said.

Mr Cooper's findings referred to an affidavit by Mr Crowden's crayfisherman employer and friend, Christopher Graeme Short, sworn in 1990.

In it, Mr Short said they were west of Bird Island when their dinghy was swamped, then lost stability and overturned.

Mr Short said he told Mr Crowden to stay with the dinghy.

He said he believed his chances of getting back to the dinghy were poor, so he swam for a gap between Bird Island and the main shore.

"After I had been swimming for approximately 15 minutes, I caught a glimpse of (Mr) Crowden still with the upturned dinghy," Mr Short said at the time.

"This was the last time that I saw him."

Mr Short made it back to his crayfishing boat and raised the alarm by marine radio.

Search efforts failed to find Mr Crowden.

Mr Cooper said the Tasmania Police Missing Persons Unit made inquiries in 2009 which he was satisfied were extensive.

"If Mr Crowden was still alive, I am satisfied that those inquiries would have identified that fact," Mr Cooper said.

He said Mr Crowden's mother, Stella Crowden, swore an affidavit in 2019 confirming she had had no contact with her son since 1990.

Mr Cooper said the extra evidence and Mr Short's account satisfied him to the required legal standard Mr Crowden was dead.

The men had been fishing on the West Coast and later travelled north, setting crayfish pots from the dinghy near Bird Island.

The dinghy was swamped the next day when they went to collect the pots.