Great Britain's Ben Ainslie became the most successful sailor in Olympic history after securing a fourth successive gold medal.
The 35-year-old replaced Denmark's legendary Paul Elvstrom as the Games' most decorated sailor after triumphing on home waters in front of thousands of supporters in Weymouth.
Ainslie faced fierce resistance throughout the week from Elvstrom's countryman Jonas Hogh-Christensen, although he managed to finish ahead of the Dane in the medal race to increase his Olympic haul to four golds and a silver.
The Brit was in control heading to the third mark and remained ahead of Hogh-Christensen, who attempted a breakaway on the last upwind leg.
The tactic did not work as Ainslie stayed ahead around the fifth mark, but the Briton was ninth and Postma had moved into second - positions that would have seen the Dutch sailor win gold.
However, attention from New Zealand's Dan Slater put Postma off towards the sixth mark and he eventually finished fifth, while Ainslie came in ninth ahead of Hogh-Christensen to win gold in a medal race won by Lobert, who took bronze ahead of Postma.
Earlier, British hearts were broken as Sweden denied Iain Percy and Andrew Simpson gold in the Star class.
The defending Olympic champions sailed exceptionally throughout the week and came into the medal race with an eight-point lead over Brazil's Robert Scheidt and Bruno Prada.
However, it was Sweden, not Brazil, that proved Percy and Simpson's undoing as the Brits lost their crown to Fredrik Loof and Max Salminen, who won the race. Britain entered the final leg of the race in sixth but slipped away in the last 100 metres to finish eighth, handing Loof and Salminen gold on the Nothe Course.