Olympic gold medal-winning Star sailors Iain Percy and Andrew Simpson (GBR) took an early lead in the Star class, with Skandia Team GBR's Ed Wright - already assured of overall World Cup series victory - also starting strongly in the Finn class.
Percy and Simpson made the best of the tricky north-easterly wind conditions - unusual for the venue at this time of year - and posted a first and a second from their two races of the day.
"We sailed pretty well and stuck to our game plan which is just to keep fighting whenever you can," Percy explained.
"It's going to be a long hard week with this wind direction but it's actually fun racing, in hindsight - at the time it's a bit scary and frustrating but you just need to keep battling and fight for every place all round."
The Skandia Sail for Gold Regatta is the first competitive event in Britain for the Star class since the 1988 Olympic trials, and with 17 overseas crews in additional to Percy and Simpson and fellow British hopes John Gimson and Ed Greig making the trip to the 2012 Olympic sailing venue.
"It's a pretty high quality field - it's not missing many. A lot of people realise it's the first real chance to sail here," Percy continued.
"We always want to do well, but realistically this event's about learning for us and there are always areas to improve on.
"For us it's about being here for Skandia, and about learning and logging what we learn and putting it in the memory bank ready for 2012."
Behind Percy and Simpson, 2008 World Champions Mateusz Kusznierewicz and Dominik Zycki (POL) won the day's second race to sit second overall, just ahead of the Swedish team of Fredrik Loof and Johan Tillander.
Ed Wright (GBR), the European bronze medallist, had a consistent opening day with two second places to set him on top of the Finn class leaderboard.
In spite of having already secured the overall World Cup series victory in the heavyweight dinghy class, Wright will hope to seal the series in style on his home waters.
Olympic gold medallist Malcolm Page and his new helm Mat Belcher (AUS) made a perfect start in the men's 470 fleet with two bullets in shifty 12-16 knot conditions putting them top of the leaderboard. Skandia Team GBR's 470 pairing of Nic Asher and Elliot Willis are in second overall with 3, 2 for their opening day's efforts. In the women's fleet, the New Zealand team of Jo Aleh and Olivia Powrie matched the Aussies' double bullet start to lead the way from this year's Junior World Champions Tara Pacheco and Berta Betanzos (ESP).
Skandia Team GBR boasts five boats currently in the top ten of the 49er class, but it's reigning World Champions Nathan Outteridge and Iain Jensen of Australia who hold the top spot after a 3, 1, 3 start. Allan Norregaard and Peter Lang (DEN) lie second whilst Welshman Dave Evans and his double Olympic medal-winning crew Simon Hiscocks lead the British charge in third.
Nick Thompson (GBR) has the overall World Cup series victory in his sights in the Laser class, needing only at top 15 finish at the Skandia Sail for Gold Regatta to claim series honours. The 23-year-old picked up 2, 5 today to sit him in joint third overall. Two-time Laser World Champion Tom Slingsby of Australia holds the overall lead after winning both opening races while Olympic, World and European Champion Paul Goodison (GBR) is 22nd.
"I only got back from the Worlds about 10 days ago, which was the big event for me for the year, so this is really a good opportunity to learn and take those sort of positives from the event really rather than looking at it as an outcome regatta," Goodison explained.
In contrast, the recently crowned Laser Radial World Champion Sari Multala (FIN) got off to a blazing start with two race wins putting her top of the leaderboard ahead of Evi Van Acker (BEL).
In the Elliot 6m women's match racing event - the new Olympic class replacing the Yngling keelboat for the 2012 Games - Lucy Macgregor, Annie Lush and Ally Martin (GBR) have a 100% record after their opening three matches against the French team skippered by Anne Le Helley, Denmark's Trine Abrahamsen and Britain's Katie Archer. Double World Champion Claire Leroy (FRA), competing in her first World Cup event, is also unbeaten as is Finland's Silja Lehtinen and the third British team skippered by Mary Rook.
Amongst the windsurfers, Greek veteran Nikolas Kaklamanakis and Brazil's Ricardo Santos lead the men's fleet, with World Cup leader João Rodrigues (POR) also starting strongly to place third overall. Meanwhile, Blanca Manchon (ESP) looks set to continue her dominance in the women's RS:X fleet. With the World Cup title already secured, the Spaniard won both opening races to lead from Charline Picon (FRA).
In the Paralympic classes, the US crews are performing strongly. Scott Whitman and Julia Dorsett (USA) lead in the SKUD18, Alphonsus Doerr, Hugh Freund and Maureen Mckinnon-Tucker (USA) lead in the Sonar, whilst Dutch skipper Thierry Schmitter heads the 2.4mR class, with World Cup series leader Megan Pascoe (GBR) is sixth overall.
The Skandia Sail for Gold Regatta at the Weymouth and Portland National Sailing Academy continues until Saturday 19 September.
ISAF Sailing World Cup
The ISAF Sailing World Cup 2008-2009 consists of the following events:
16-21 Dec 2008 - Sail Melbourne The Asia Pacific Regatta, Melbourne, Australia
25-31 Jan 2009 - US SAILING's Rolex Miami OCR, Miami, USA
4-10 April 2009 - Trofeo SAR Princess Sofia MAPFRE, Palma, Spain
18-24 April 2009 - Semaine Olympique Francaise, Hyeres, France
27-31 May 2009 - Delta Lloyd Regatta, Medemblik, Netherlands
20-28 June 2009 - Kieler Woche, Kiel, Germany
14-19 Sept 2009 - Skandia Sail for Gold Regatta, Weymouth, Great Britain
Find out more about the ISAF Sailing World Cup, including the World Cup Standings, more on the seven events, the scoring system and the Notice of Series at www.sailing.org/isafsailingworldcup.