The 32-year-old returned to the exact same waters where he won RS:X silver at last summer's Olympics and recovered from a poor start to taste more success in Weymouth and Portland.
Dempsey, who also won Olympic bronze at Athens 2004 in addition to his silver at London 2012, traded first and second-place finishes with Carney throughout the RS:X 9.5 series.
That left a winner takes all scenario in the medal race with Dempsey, the first man ever to win two RS:X world titles after victory in Brazil back in March, getting the better of Carney.
Dempsey finished first to Carney's second, proving he is still the man to beat in Britain and admitted that was just what he needed ahead of the European Championships, which begin in France at the end of the month.
"I had a pretty bad day on Monday, and I think other than that it hasn't been so tight, but I certainly put a bit of pressure on myself having such an awful day on Monday and I certainly had a bit of work to do for the rest of the week," said Dempsey.
"But it's turned out pretty good in the end and I'm pretty happy with how the event's gone. It's been perfect preparation for the Europeans in a few weeks' time.
"I was confident. It was quite windy and I'm pretty comfortable in those conditions and I know that if I get a clean start then I should generally just sail away from the fleet.
"But you never know, a lot can go wrong and you just have to be careful and do everything you can to minimise any risks.
"Elliot sailed really well and it's been a really nice mix of conditions and it was quite close all the way to the end so it was nice to finish it off in the medal race."
Sail for Gold acted as the third stage of the inaugural EUROSAF Champions Sailing Cup series with Bryony Shaw, an Olympic bronze medallist from Beijing 2008, taking overall victory in the RS:X 8.5 class.
The Nacra 17 fleet didn't make it off the dock leaving Ben Saxton and Hannah Diamond victorious as part of a British one-two-three ahead of Lucy Macgregor and Tom Phipps and Pippa Wilson and John Gimson.
Meanwhile Mark Andrews claimed his second successive win on the EUROSAF Champions Sailing Cup series with victory in the Finn, fellow Brit Andrew Mills' capsize aiding his cause.
Charlotte Dobson and Nicola Groves held on to gold in the 49erFX with Kate Macgregor and Sophie Ainsworth second while Dylan Fletcher and Alan Sign won the two medal races in the 49er fleet to jump up and take silver.
Nick Thompson held onto bronze with a fourth in the Laser medal race while in the Laser Radial Ireland's Annalise Murphy kept Briton Chloe Martin at bay as she took the final medal.
© Sportsbeat 2013