Rio 2016 Olympics: Serbia capsize as rowers struggle with conditions in Rio

Wind and choppy waters mean that many of the competitors are struggling to find their best for in the rowing at Rio.

Olympic rowing legend Steve Redgrave explained just how it affects the rowers.

The regatta kicked off with a samba band playing on the finishing line pontoon. But as the morning drew on, the winds whipped up the waters, especially in the lagoon's less-sheltered middle section, making for slow times.

It became a real test of the rowers' skill and a lot of crabs were caught.

Australian Kimberly Brennan, favourite for the gold medal in the women's single sculls, almost became an early casualty. She left it until late in her heat to overhaul Korea's Kim Yeji for third spot and a qualifying place, avoiding the repechage.

She tipped a good bucket-load of water out of her boat at the finish. Brennan, hoping to become the first non-European rower to win Olympic gold in the women's single sculls, only managed 14th place in the heat rankings, which were topped by Mexico's Kenia Lechuga Alanis.

"I've been speaking to a lot of rowers in the boat park and there's a lot of discontent," she told reporters. "I was pretty close to sinking out there, which would generally be an indication that the course isn't rowable."

The International Rowing Federation said it was monitoring the conditions closely and was satisfied they were the same for all competitors.

In the men's pairs in which all-conquering New Zealanders Eric Murray and Hamish Bond romped home, the Serbian boat crewed by Milos Vasic and Nenad Bedic sank.

Egyptian sculler Nadia Negm said the conditions were intense.

"Halfway through the course this huge wave just went into my boat. It went all the way up to my face. I mean, I'm lucky I didn't tip over," she said.

"I've never really raced in water like this. This was a new extreme, but it's good experience. In the end I kind of feel like a Viking coming out of it."