21 rescued from raft off Queensland

File photo / Bay of Plenty Times

More than 20 people have been plucked from a life raft off Queensland after violent weather pushed their vessel onto a reef, causing the boat to capsize.

Police say rough weather caused the charter fishing boat to capsize at Swains Reef, about 200km off Yeppoon, about 5.30am (AEST) on Wednesday.

An emergency beacon was activated, alerting authorities.

Inspector David Peff said a passing fishing vessel plucked all 21 from a life raft before police arrived. It's unclear whether any were thrown from the sinking vessel and had to tread water before climbing into the raft.

Marine Services Queensland is investigating the cause of the accident.

Mr Peff said the fishing vessel used its six-foot dory, a shallow draft boat, to reach the raft and transport the stranded to the ship.

"We do know there was fairly rough seas out there with significant winds," Mr Peff said.

"I heard it got up to 50 knots, that's quite rough."

He said the rescued had minor scratches and bruises.

They are being transported to Yeppoon in a police vessel and are expected to arrive around 8pm (AEST).

A major rescue operation was launched after the Australian Rescue and Safety Authority (AusSAR) detected two signals from emergency beacons.

Authorities immediately mobilised a fixed-wing aircraft, three emergency choppers and three nearby vessels.

"At 7.20am, AusSAR advised all 21 crew and passengers were in a life raft," a police spokeswoman said.

"AusSAR then made arrangements for a local vessel to rescue all 21 passengers."

Bureau of Meteorology forecaster Gavin Holcombe said there was storm activity in the region overnight.

"At that particular time there was a trough in the area," he said.

"We measured wind speeds around 20 to 25 knots in that area. It could have been higher, we just don't know. They were in an area where there's very few observations."

The owner of the capsized boat, Bell Cay Charters, based in Yeppoon, said its 22-metre vessel was hit by huge winds overnight.

"They had big winds - 52 knots of wind - I've been informed by maritime safety," a partner in the business, Wayne Thorpe, told AAP.

"They had a 180-degree wind change about 1am (AEST)."

Swains Reef is a popular spot for offshore fishing and many charter vessels run trips there.

- AAP