New Zealand sailor Dean Barker has revealed he was battling cancer while training for American Magic's 2021 America's Cup campaign.

The former Team New Zealand skipper appeared on TVNZ's Sunday to share his story of being diagnosed with bowel cancer and receiving chemotherapy over a period of six months, all while keeping his sailing dreams alive.

Barker was 46 at the time of diagnosis and said he felt fit and healthy when he first suspected something was wrong inside his body.

"I started noticing a bit of blood in my stool and didn't really think a lot of it, but it sort of carried on for two or three weeks," Barker said.

Barker then mentioned what was happening to the American Magic team doctor, who told him to get checked, just to be sure.

"So less than a week later I'm in for the colonoscopy thinking it was gonna be all good. You wake up, you're still kind of a bit blurry from the anaesthesia... and he says 'oh look, unfortunately we've found a tumour and you're gonna have to get it removed."

The following week, Barker was in surgery.

"The tumour was removed and, at the same time, they took 23 lymph nodes, just to see whether or not the cancer had spread through the body at all and, unfortunately, when that came back, it was six of the 23 lymph nodes showed signs of cancer and really the only option at that point was to go into chemo.

"There was a fork in the road and it was always the wrong one, all the way through. Colonoscopy, they said 'don't worry, it'll be fine', it wasn't. Then it was 'oh, we'll take the tumour' and they get rid of that and you think that that's the end of it and it wasn't, and then it's the chemo."

Every fortnight on a Monday he'd receive a new round of chemotherapy which involved a day of treatment in a clinic, two days of slow-release treatment at home and two days of recovery. He'd then hope to be well enough to rejoin his teammates in America's Cup training by the weekend.

This routine went on for six months, during which he received 12 rounds of treatment; and all the while American Magic was ramping up towards competition.

"[It was] probably his greatest challenge ever," his wife Mandy said of the ordeal.

"As you can imagine, when you're probably thinking it's not something bad and sinister, and you get that news, it came as a real shock."

Dean Barker with wife Mandy in 2013. Photo / Getty

Barker told barely anyone about his battle at the time, with just close family, American Magic team owners and team skipper Terry Hutchinson aware of his situation. He's only telling his story now to raise awareness about bowel cancer and to encourage people to get checked by medical professionals if they suspect something amiss within their guts.

Three years on from his trial, Barker says he's feeling well, cancer-free, but also far more aware of his own mortality.

"I just got my yearly CT scan result yesterday.., all clear, it's obviously a huge sigh of relief but, in some ways, it's always in the back of your mind."