Australian sailor missing off Chile

An Australian sailor missing off the coast of earthquake-ravaged Chile was on board a yacht whose captain has previously sailed without a radio and reported false information to authorities.

The family of Mitchell Westlake last heard from the 23-year-old Gold Coast man on January 16.

Chilean authorities have launched a search for the 13-metre yacht SS Columbia, crewed by Mr Westlake and four others - Polish-born French captain Boguslaw (Bob) Norwid, his partner 49-year-old Canadian Jade Chabot and another woman from British Columbia.

Mr Westlake's grandfather Ernie Westlake told AAP he had last heard from the former Australian navy midshipman on January 16 when he was having difficulty accessing money.

"He needed some money to pay the balance of the fee (for the open-water sailing course)," he said.

Mr Westlake's last Facebook posting on January 16 read: "I hate you Commbank."

He left Salinas, Ecuador on board the British-flagged vessel on the same day.

"No one has heard from him since," his grandfather said.

The yacht was expected to dock at the Chilean city of Coquimbo between February 24 and 27, the day the earthquake struck.

His grandfather said he understood Mr Westlake and the two Canadians decided they should head to Robinson Crusoe Island, about 130km off the Chilean coast.

"If he was at sea the tsunami would not have affected them, but if they were anchored he could be in trouble," he said.

The Canadian Coast Guard told the Montreal Gazette newspaper the captain had informed Ecuadorian authorities on January 17 he was sailing straight to Coquimbo.

But the vessel's call number appeared fake and did not appear in any database, the Coast Guard said.

The newspaper reported that in 2002 the same yacht under the same captain disappeared for 13 days on its way from Vancouver to Mexico before it finally arrived in Manzanillo.

On its return, the captain explained that they had had to sit out a storm and wait in the middle of the Pacific Ocean for favourable winds.

A message was posted on the Columbia's website at the time: "Such can be the cruiser's life, but without SSB (marine radio), Sailmail (email service for yachts) or Satphone, it can be tough on families of `novice' crew when there is no communication - worry sets in quickly based on the pure unknown!"

Mr Westlake's grandfather said he understood the skipper was experienced and the yacht was "very good".

His grandson had spent 20 months in the Australian navy before quitting to work in a gold mine at Cobar in NSW before heading overseas.

"He left in August last year and he's been wandering around South America," Mr Westlake said.

He said Canadian and Australian governments had been "most helpful" and pressured the Chilean authorities to keep searching.

"The more people we can get looking the better," he said.

A Department of Foreign Affairs and Trade spokeswoman said it was providing consular assistance to Mr Westlake's family and liaising with local Chilean authorities.