After the demanding 30 knot winds which swept across Portland Harbour for the opening day of the regatta, Saturday's breeze was much moderated for the 163 contenders at these Championships, with the women's fleet the first to get racing in 15 knots shifty wind conditions.
Alabau maintained her perfect scoreline, with two more firsts from the two races held, to extend her lead to nine points over France's Eugénie Ricard, with Blanca Manchon (ESP) in third making it two places in the top three for the Spanish girls.
Shaw, Britain's Beijing bronze medallist, picked up two second places to pull her into seventh place overall, and help her put a difficult opening day behind her.
"I think I've woken up!" Shaw explained. "I think yesterday I was a little bit asleep, but today I'm back in the game.
"Yesterday was tough - I haven't really sailed in that stuff for a long time, and I wasn't really set up for it.
"So I had trouble trying to clear my head yesterday evening, but I'm trying to treat each day as a new one, sail smart and sail how I know I can and that worked for me today."
The Netherlands' Dorian Van Rijsselberge was the man to beat in the men's fleet on Saturday, with two firsts elevating him from his overnight position of seventh to the overall top spot in the men's standings.
"It was nice conditions and hard work," explained van Rijsselberge, "but I didn't get it for free - I had a little bit of a battle with Nimrod [Mashiah (ISR)] in the first race, and in the second race it was almost the same with Ivan [Pastor (ESP)]."
The Dutchman, who's won three of the six events of this year's ISAF Sailing World Cup series is confident of his form heading into these Championships.
"I'm training with Casper [Casper Bouman (NED)] who is one of the fastest guys out there on flat water. We've done a lot at home, and some training out here as well, so I'm pretty confident to knock some more bullets in out there."
Van Rijsselberge is on equal points at the top of the men's leaderboard with Skandia Team GBR's Nick Dempsey, who scored hard fought fourth and third places respectively from his two races today to maintain a solid scoresheet.
The overnight leader, Przemyslaw Miarczynski of Poland, is in third place tied on 12 points with Brazil's Ricardo Santos and Bouman after four races.
Racing at the 2009 RS:X World Windsurfing Championships continues until Thursday 10 September, with Monday 7 September scheduled as a reserve day.
Results - click here
Click here for our RS:X World Championships page containing all the news, photos, links to live results and more from this year's RS:X Worlds.
The RS:X World Windsurfing Championships is the second of three back-to-back World Class events being run by the RYA, supported by UK Sport, and hosted at WPNSA. The IWA Junior, Youth and Masters Windsurfing Worlds was held from 22-29 August, with the Skandia Sail for Gold Regatta - the final round of the 2009 ISAF Sailing World Cup series - set to welcome the cream of the World's Olympic Classes sailors from 14-19 September.