The duo was level with the race leaders over the first kilometre but couldn't keep pace as the United States streaked to victory. Cook and Crow finished the 2km course in 7min9sec, three seconds behind the winners.

Australia's Ben Houlison claimed the bronze medal in the adaptive men's single scull.

Houlison, who is competing in his first world championship regatta, slightly missed the start but showed his power through the middle of the race to move through the field and claim third on the line over US rower Ron Harvey.

Britain's Tom Aggar defended his world title with another commanding performance, finishing in a time of 4:51.48.

He finished 15 seconds clear of Ukraine's Andrii Kryvchun, while Houlison crossed the line in 5:12.11.

Houlison said he expected the field to get a good jump from the start.

''We had a tail wind so the plan was to pick a speed and stick to it,'' Houlison said.

''I had to come over the New Zealander and USA rowers in the last 250 but that was the plan.

''I'm ecstatic. The plan was to make the A final and to come away with a medal is fantastic.'' The adaptive mixed coxed four of Henry Macphillamy, Peter Siri, Carol Cooke and Alexandra Green, coxed by Lisa Brown, finished sixth in their final.

The race was taken out by Britain in a time of 3:25.33 ahead of Italy and Germany.

And the Australian men's four placed second, with Francis Hegerty (NSW), Cameron McKenzie-McHarg (VIC), James Marburg (VIC) and Matt Ryan (NSW) adding world championship silver to the Olympic silver they won last year.

Britain and Australia took the race out quickly as expected and the two crews had opened a sizeable margin on the rest of the field at the halfway point.

Britain moved out to a boat-length lead by the 1250m mark and despite the best efforts of the Australians they were unable to reel in the Brits, who crossed the line in 5:47.28. Australia was three-quarters-of-a-length back in 5:49.20.

For more, pick up a copy of today's Canberra Times