Mark Gore’s dad, Bernard Gore, was declared missing on January 6 after he failed to meet up with his wife at a shopping centre in Bondi Junction.

The devastated son said he believed his father, who suffers from dementia, was trying to get home.

“Where he thinks home is at the moment, I don’t know, whether he is trying to get to Hobart or to my sisters I’m not sure,” he said.

Mark said it was not the first time his dad had disappeared.

Last year Mr Gore planned to meet his wife at the shops in Hobart and went missing for about seven hours.

“It was the same scenario. Mum was running a little late and he didn’t wait around. He was confused when we found him.”

After spending two weeks searching in NSW, Mark has returned home to Tasmania.

“I was over there for 14 days walking around, looking and in the end I felt a little lost myself.

“Mum is still there over there, she won’t come back until he is found.”

Mr Gore was last seen wearing a grey skivvy underneath a red chequered flannelette shirt, grey trousers, white sneakers and a Panama hat. Police said he may also be wearing a pair of blue pyjama pants.

He is described as being slim and tall, about 180 centimetres, and of caucasian appearance.

“He’s been missing for 17 days now, it’s just a really confusing time for us all, we’re just living on hope at the moment,” Mark said.

“I think I have nearly been through every possible scenario, some aren’t very nice … the only thought we have at the moment is that if he was injured he would have been found. So we still hold pretty strong hope he’s still out there, walking around.”

Mr Gore’s 18-year-old grandson Samuel said he “just hoped he was found soon”.

“I can't imagine what it is like for him being lost in a place surrounded by things that are not familiar to him,” he said.

Anyone with information should contact Crime Stoppers on 1800 333 000.