His victory in Taupo did not flow on to bigger and better things in his two major quests last year, at the 70.3 Worlds and his debut at the Ironman World Championship in Hawaii. He failed to finish in both - illness proved costly at Las Vegas while his nutrition failed him and he ran out of fuel in Hawaii.
"It certainly wasn't the finish to the season I had planned," Docherty said.
"I was in terrific shape but this endurance stuff, particularly Ironman, is new to me. I said when I took it up that I was confident about swim, bike and run but there's a fourth discipline which is nutrition that is new to me.
"I'm learning all the time and I am pleased with my training. I am strong and things are tracking well for me."
He has another incentive with his father Ray also competing in the 30th anniversary event.
American Kessler is chasing her third straight victory in Taupo.
Nine-time iron distance winner Gina Crawford will lead the New Zealand charge.