The Middle Eastern Organised Crime squad has taken over the investigation, which involves two crime scenes: the luxury yacht Oscar II and a street in Bondi, where a man was found with gunshot wounds to his shoulder.

The man is believed to be 31-year-old Farhad Qaumi. The victim discharged himself from from St Vincent's Hospital on Thursday morning and police are still to interview him.

In 2009, Mr Qaumi was acquitted of murdering boxer Bassam Chami, 26, and his high-school friend Ibrahim Assad, 27, in Blaxcell Street, Granville, on March 29, 2006.

But he was then charged in April 2012 with the murder of Sydney underworld figure Cengiz Sarac, who disappeared in 2005.

Mr Sarac, 24, was last seen driving away from his Auburn home in 2005. It is believed he was killed because of a dispute over drugs and money. Police received a tip-off that Mr Sarac was buried underneath a house at Merrylands in Sydney's west while it was being built. Police then dug up a hand bone believed to belong to Mr Sarac.

The charges against Mr Qaumi did not proceed.

Mr Qaumi is believed to be a member of Brothers 4 Life, which has come under intense police scrutiny after a spate of violent incidents across Sydney in the past year.

Police arrested 10 members of Brothers 4 Life, including de facto leader Mohammed Hamzy, in November last year after vowing to crack down on the gang.

In Wednesday's incident, police believe the injured man was struck by one of at least 18 bullets that hit the Oscar II as it docked about 11.30pm on New Year's Day, shattering its windows and leaving its hull peppered with bullet holes.

The gunman is believed to have fled through the nearby Royal Sydney Golf Club course.

The 105-foot motor yacht, which is available for hire for $2400 an hour in high season or $95,000 a week, pulled away from the wharf following the shooting before it was stopped by police a short time later. It is owned by a company controlled by the Gravanis brothers, who own a string of hotels in Sydney, including Oscar's in Pyrmont.

The brothers had only just bought the Oscar II and it was being crewed and operated by All Occasion Cruises, owned by Joe Elias, brother of former Tigers great Benny Elias.

The Oscar II has been towed to the NSW Police Marine Area Command, where forensic police are examining it.

Sydney's most dangerous suburbs: Explore data on shootings in Sydney since January 2012.

Boating website Charter World said the luxury vessel boasts "top-of-the-range facilities and is stylishly furnished in understated elegance".

It can accommodate eight guests in four "staterooms" and has a saloon, a formal evening dining area, cabins with private en suite facilities and a bar on the deck.

In October, the yacht hosted the Vogue Australia November magazine issue launch party, attended by Erica Packer, who featured on the magazine's cover.

The gangland style shootout has shocked residents of the eastern suburbs.

"An incident at this location, in respect to the shooting at the Rose Bay commuter wharf, is totally out of character for this area and I'd ask anybody that might have been in the vicinity last night who may have information, might have seen something, might have heard something, if they could contact Crime Stoppers," Detective Inspector Damian Henry, from Rose Bay police, said.

He said police from Strike Force Talon, formed to investigate gun crime in Sydney, would be involved in the investigation.

Anyone with information has been asked to phone Crime Stoppers on 1800 333 000 or to use the Crime Stoppers online reporting page.