Sailors battling it out in the Rolex Sydney Hobart Yacht Race performed a special honour to the 15 people killed in the Bondi shooting.
All 129 yachts were set to scatter rose petals off the stern of their boats as they passed Bondi Beach south of Sydney Harbour.
One retired before the race started.
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The tribute was outlined during the Compulsory Race Briefing by Cruising Yacht Club of Australia Commodore, Sam Haynes, organisers said.
"The tribute that we mentioned for the tragic events in Bondi has been very well received by the Jewish community, but also internationally recognised worldwide, and obviously here in Australia," Haynes told the assembled fleet.
He said Mr Roses supplied petals for crews.
"For many competitors, the moment will provide a pause for reflection early in a race more commonly associated with speed, rivalry and endurance," organisers said.
"Just hours after the start, as spinnakers are hoisted and the fleet accelerates south, the scattering of petals will briefly shift attention away from tactics and weather to remembrance and solidarity."
It's the 80th year of the Boxing Day race, which sees crews battle it out over 628 nautical miles from Sydney in NSW to Hobart in Tasmania.
The race started just after 1pm.
Sailors have been placed on high alert, with officials warning of likely injuries during what is predicted to be a treacherous first night at sea.