A few years ago that dream seemed over for McDowell.
"An achilles heel had been that he'd start but not pursue things to the end," Walker said. That cost him the incremental gains that come from disciplined training year on year.
"The difference this time has been the persistence."
Walker had seen McDowell about, even trained a few times with him years ago when Walker was a star of the Coast To Coast multi-sport race.
McDowell seemed to slip out of the sport about the time Walker - thrice a Halberg coach-of-the-year finalist - joined the staff of Canoe Racing NZ.
Roll on to a few years ago when McDowell was back doing his own thing on Lake Pupuke. "I thought, 'gee, that guy is good," Walker recalls. "Above all, he had natural speed."
McDowell is a water baby. He grew up on the beach at Titahi Bay, Wellington. His first love was surf-lifesaving. Then in swimming he showed the family ability (Olympians Paul and Dean Kent are cousins). That was put aside in his late teens when he was picked in a junior canoe team to go to Europe. "It was, do I keep swimming throughout winter back home or go to Europe kayaking? It was sort of a no-brainer. That was the start of it."
By age 18 he was living in Gisborne under the tutelage of Olympic champion Alan Thompson, one of the legends of the 1984 Olympics.
McDowell made open teams but it was a time of political ructions and cultural change in the sport. He became disillusioned, missed teams, dropped out, began to study marine engineering and went back to paddling a surf ski for fun and fitness.
He reappeared on the canoe scene three years later in 2014, winning a national title. He then linked with Walker and Carrington. His great leap forward came last year. He emphatically beat former world champion and Olympic medallist Ben Fouhy at the nationals in the K1 1000m, an Olympic event. He franked that form on the international stage with two seventh placings in World Cup events, plus a third in the non-Olympic K1 500m. Suddenly, long-abandoned dreams seemed possible.
McDowell puts his progress down to training smarter. "It's taken Gordie a while to get through to me how to train properly. When I was younger I was a bit up and down."
Pain was never his barrier. He can dig as deep into the hurt box as anybody, says Walker, but a spirit like Monty Python's Black Knight is less important than consistency.
"He would go extremely hard in some [training] sessions. The discipline for him is, you don't need to go that hard today but you do need to go nearly that hard every day."
It's helped too, to have an inspirational training buddy.
Is Carrington faster? "No, no, I can still get her but you wouldn't want to take her lightly!" says McDowell. "It's a confidence-booster to know what we are doing is working. It's going to take a bit of time for me but every year it's getting better and better."
Walker: "When he made the team it was a really proud moment also for myself and Lisa, because out of that environment he's achieved something most competitors can only dream about. And he's still got some improvement in him."
The pinch-yourself tone in McDowell's voice says everything about his journey. They leave this weekend for World Cup events in Europe. Then, says McDowell, his focus will turn to making the final at the Olympic Games. "You make that and anything can happen."