Rowing 200 kilometres of ocean over the span of seven days is gruelling enough, but when Harriet Walker participated in the George Bass Surf Boat Marathon two years ago, the challenge was particularly tough.

A few short months before the race, Ms Walker lost her father and "number one fan" Greg Walker to gastro-intestinal (GI) cancer.

"I was starting out training for the Bass in 2013 and my father was diagnosed with GI cancer, stomach cancer specifically," she said.

"He passed away four months after diagnosis ... It's one of the cancers that has the lowest survival rates.

"He was always the one who would tell us to go that little bit further so in that respect he's definitely missed but it's nice to be able to keep on going with that."

Ms Walker said the race, which sees teams of rowers travel along the New South Wales South Coast from Batemans Bay to Eden, took an especially hard toll on her.

"It's a tough race as it is, and that other level of grieving on top of that was definitely something that was quite difficult for me," she said.

For this year's marathon Ms Walker has returned to the waves to raise money for research into GI cancer, with the help of her team the Broulee Capitals.

Ahead of the race, she said the team had been preparing well.

"My crew have been training really hard, our coach always pushes the envelope with us, and we've been responding," she said.

"I'm feeling a bit more settled ... It's nice to know that I've done it and to know that I could finish it.

"We're looking forward to hitting the waves, seeing what we can do and what we can achieve."

The race started on Saturday and has seen teams battle through harsh winds and colder than predicted temperatures.

The Broulee Capitals were in second place at the end of Wednesday's leg, and the race is due to finish this Saturday.