Dame Ellen MacArthur and her record- breaking trimaran B&Q were beaten into third in their category in Saturday's Round the Island Isle of Wight race.
The 28-year-old took seven hours, 27 minutes and 53 seconds to complete the 50-mile course - 17.06 mins behind Open 60 class winner Emma Richards.
Richards clocked 07:44.59 in Pindar Alphagraphics, with fellow Briton Mike Golding and Ecover second in 07:53.08.
MacArthur said: "We couldn't keep up but we loved every minute of it."
The fastest round-the-world solo sailor was competing in the Island challenge for the third time - but it was the first occasion for her 75ft boat.
She was one of almost 1700 competitors taking part in the event, which started and finished off Cowes and went anti-clockwise around the island.
Now MacArthur will turn her attention to her attempt on the solo trans-Atlantic record, which is planned for September.
Last June, she missed out on setting a new mark by just 75 minutes.
The record - set by France's Laurent Bourgnon on the 60ft trimaran Primagaz in 1994 - stands at seven days, two hours, 34 minutes, 42 seconds.
And the Briton believes this quest could be her toughest yet.
"A lot of people say 'Oh you've been around the world, what's the point of doing the trans-Atlantic?'", she said.
"But that's not reality. The reality is you have to work that much harder to break the trans-Atlantic record, albeit just for seven days.
"If you lose time, you haven't got much time to catch up.
"It's the difference between a marathon and a sprint."
She is also heavily involved with the Ellen MacArthur Trust, a charity set up to help children suffering from leukaemia or cancer by introducing them to the joys of sailing.
"It's a big priority," she added.