A little bit of East Coast surf proved the perfect recipe for upsets in the second round of the New Zealand surf boat series in Whangamata today.

Reigning national women's champions Mairangi Bay and men's titleholders Piha both suffered shock losses in the final, each beaten into third as a tricky half-metre swell caused havoc.

It was left to the young Orewa women's crew to claim the female spoils, heading home Mount Maunganui, while Titahi Bay's crew of mostly under-23 rowers came through to win the men's final, ahead of Muriwai.

Titahi Bay were helped by the presence of 33-year-old Tim Marsden, a multiple national champion, who helped keep cool heads even as his crew turned fourth around the cans.

"We're a bit of a throw together crew, even though the under-23s have been training together for a while," Marsden said.  "We were missing one of the boys but we wanted to keep racing them so I jumped in, even though it's been a while since I was under-23!  We were behind a little when we turned but we'd saved a little bit in the tank for the row home in case a wave came, and luckily it did."

The Mairangi Bay ladies were left gutted, however, after leading most of the way, only to fall off the back of a small wave and broach in the next one.

That allowed the Mark McCarthy-swept Orewa crew - featuring 21-year-olds Nicole Keinzley and Nikki Jones, 20-year-old Brearna Franich and 19-year-old Nastassia Randell - to come through.

"The girls rowed really well coming home and put a massive effort in and it was great to pull that wave down," McCarthy said.  "Mairangi Bay had a pretty good lead but that's what surf can do - you need that little bit of luck and we were in a position to grab it."

Though the defeat burned, Mairangi Bay second stroke Nina Reid hoped it would eliminate any complacency for the rest of the series.

"Unfortunately the exact same thing happened to us this time last year and we were determined not to let it happen again but sometimes you just don't get the choice," Reid said.

The under-23 men's division needed a countback before the Piha Pirates headed off the Piha Pistols. Piha's under-19 women's crew also triumphed, while the Waihi Beach under-19 men's crew - swept by 73-year-old veteran Dan Harris - won their division from the local Whangamata crew.

Results from the second round of the New Zealand surf boat series in Whangamata today:

Men:

Open: Titahi Bay SLSC (Jono Boyd/Nick Boyd/Tim Marsden/Jordan Te Paa/James Livingston) 1, Muriwai (Kendall Dooley/Dan McCormack/Rick Wells/Tim Wilson/Ben Taparau/Hayden McIntosh/Ricky Butt) 2, Piha (Matt Kirk/Scott Lissington/Chris Morris/Ben Scott/Paul Gerrutrsen/Mark Bournville) 3. Under-23: Piha Pirates (Nicholas Mackenzie/Shamus O'Halloran/Jed Wright/Cahon McCarthy/Shane O'Halloran) 1, Piha Pistols (Cedric Bourneville/Ludovik Bourneville/Benjamin Richards/Oliver Sawbridge/Jean-Paul Smit/Mark Bourneville) 2. Paekakariki  (Samuel Perry/Kurt Walsh/Steve Dickson) 3. Under-19: Waihi Beach (David Grant/Jack Kinsford/Josh Williamson/Dan Harris) 1, Piha SC Chargers (Rhye Jacka/Tom Rasmussen/Charlie Henderson/Hamish Mitchell/Mark Bourneville) 2, Whangamata (Josh Kerridge/Sam Stockley/Anton Wood/Brandon Dromgol/Steve Pipe) 3.

Women:

Open: Orewa (Brearna Franich/Nicole Keinzley/Nastassia Randell/Nikki Jones/Mark McCarthny) 1, Mt Maunganui (Bethany Hopper/Mare Haitsma/Charolotte Jones/Ashlea Stanford/Clayton Kellett) 2, Mairangi Bay (Nina Reid/Carmel Tolhurst/Erin Tholhurst/Sarah Woolley/Rob Jones) 3. Under-21: Piha (Audrey-Lise Bourneville/Claudia Goff/Gracey Monteith/Alice Rasmussen/Vicky Peck/Amelia Brown/Ben Scott) 1, Rarangi (Fleur Lovejoy/Taylor Rogers/Georgia Ryan/Harriet Ryan/Norman-Jean Tyson/Alex Williams/Neil Watts ) 2, Bethells Beach (Ellouise Bray/Madeline Disberry/Nikita Parkin/Olivia Sale/David Oldham) 3. Under-19: Rarangi (Katie Burnett/Anna Hawkins/Danielle Sutherland/Ellen Taylor-Byrne/Taylor Rogers/Neil Watts) 1, Bethells Beach (Lindsay Cleaver/Lauren Van Gent/Hira Edmonds) 2.