Howlett said his father tried to find the author of the note, which was accompanied by a menu from the MV Wanganella's 1935 voyage from Sydney to Auckland, New Zealand.
He said the bottle was dropped overboard during the voyage and included a Ballarat address for a Mr. and Mrs. Robert Hare as well as the note's author, Billy Hare.
Howlett said the bottle's contents ended up forgotten in a drawer when his father discovered the family no longer lived at the listed address and he was unable to track them down.
Howlett harnessed the power of social media to help find the family and gave an interview to ABC Radio Brisbane that led to his being contacted by Lindy Hare, daughter of William "Billy" Hare.
"We have tracked down the family in the message and I have spoken to Billy's daughter today," Howlett wrote on Facebook. "We are arranging to meet and swap stories soon. It's very cool, and I am so pleased we've been successful in finishing a story that started so long ago."
Lindy Hare said her father died in 2013, but she still has some family photos from the trip to New Zealand where he launched his bottled message.
"It was lovely to have something from beyond the grave from him. He would have been so thrilled," Hare told the Australian Broadcasting Corp.
Hare said the message in a bottle was just the start of her father's remarkable life -- he became Australia's first radiology professor, responsible for bringing the country its first ultrasounds, angiograms and breast screenings.
Howlett said he will let Hare decide what to do with the documents from the bottle when he meets her in person later this month.
"I'll leave it to her whether she wishes to keep them herself or, if not, perhaps it's museum fodder," he said. "It certainly would be unfortunate to see it in the back of a drawer for another 50 years."