The Rotorua Association of Triathletes and Multisport and Tau te Mauri athlete admitted being disappointed not to beat last year's 12h 05m but was relieved to finish in difficult conditions.
"I was just glad to finish in the end," he said.
"I threw my arms up in the air because blimey it was hard.
"I knew straight away I was over the time I wanted to clock, but last year's conditions were perfect for racing, this year's certainly wasn't.
"Last year I smiled heaps and was a chatterbox right through because it is such a great natural high but this year I was just zipped and focused."
Rangitutia recorded split times of 1h 33m 14s in the 3.8km swim in the fresh waters of Lake Taupo, 6h 13m 15s over the undulating 180km two lap bike track along natural forest and farmland surrounding the region, and 4h 33m 02s in the final three-lap 42.2km run.
"The water was rough and choppy. The waves would bring a swimmer smacking against you. It was really intimidating. There were a few times I just had to dig deep and carry on otherwise your day is over.
"I tried to make up time on the bike but there was a lot of wind on the bike ride so it made it very hard coming back to Taupo on the road.
"For me the run was the hardest part. I couldn't find that strength, I was trying to dig deep but I was a little flat. Thankfully I finished strong."
Rangitutia said he used last year's half (December) and quarter (November) Ironman Maori events as preparation and was recently training up to 22 hours a week, with at least three early 4am starts.
Waiting for the father-of-five at the finish line was his cheering family, including his mum Te Aroha, 64, attending her first triathlon.
Rangitutia, who has also been trained by Rotorua swim coach Henk Greupink, said he was "overwhelmed" by his support.
"I've had to sacrifice a lot of family time in preparation, I did very early starts so it was out the way before the kids woke up," he said.
"I saw most of my family at the end so this year I took my time going down the red carpet finish just to soak up that time and hug all of them. Last year I just legged it.
"It was especially emotional that my mum was there. She loved the day. She didn't know what to expect and Saturday morning before the swim I wasn't sure if she'd be at the early swim start. I was trying to wake her up, I had to wake her up twice but she was glad. It hasn't inspired her to enter though."
The Red Stag Timber worker now has more time for his other passion - drumming, but was also focused on his eighth Rotorua Marathon in May, aiming to beat his personal best of 3h 39m.
"I'll get some time back now, and we're (Kindred) focused on writing our own music," he said.
"They are very different disciplines but I've found all this training has helped my drumming, especially with stamina. I also feel I was able to be more creative on the drums.
"In the marathon anything under four hours would be good but I could probably beat my record if I trained for it."
And the multi-talented man hasn't ruled out a third Ironman New Zealand next year.
"Immediately after race day was done I thought 'stuff this', but now I'm like I have to do it again - it's unfinished business and that's the Ironman bug right there."