Tyler Butterfield went to Hawaii with the ambition of achieving a top-five finish at the world’s greatest triathlon.

That did not work out quite so well, but sport’s glorious uncertainties and Butterfield’s selflessness have meant that he can instead leave America’s 50th state singing the praises of a 46-year-old mother who has become a world champion.

Butterfield, who entered the Ironman World Championships as one of the favourites in the elite professional field, was forced out of the race almost two thirds of the way through when an unforeseen back problem made it impossible for him to complete the 112-mile bike segment.

More than five hours later, Karen Smith was crossing the line as the first woman in the 45-49 age group, having passed the long-time leader inside the final mile of the marathon.

“That is amazing,” Butterfield said when informed by The Royal Gazette of Smith’s achievement. “I have goose bumps with you telling me that. She had some health issues last year and to come back and win? That’s made my weekend.

“It’s an amazing feat. In the US, to win your age group is enormous. You’re the best in the world. It’s an honour to be a world champion and Karen’s delivered. This washes away my sorrows.”

Smith, who spent most of this summer perhaps better known as “Tyler Smith’s mum”, such has been the impact that her son has been making in triathlon and cycling, seemed destined for simply a podium finish.

That would have been exemplary in and of itself, given the problems that forced her to miss the 2013 race, but Smith found the extra reserves of energy in the last of the 140.6 miles that make up a punishing test of endurance.

She had wanted to crack 10½ hours for the 2.4-mile swim, 112-mile bike and 26.2-mile run, but cracking American Diana Hassel before crossing the line first out of 81 in her age group in 10hr 36min 37sec proved much more satisfying and rewarding.

“The race was amazing and a dream come true!” Smith said yesterday. “I’m still in shock that I won, as I thought the gap was too big to close.” But Smith’s coach, Paul Regensburg, sensed that Hassel was weakening in front and gave his charge one final instruction to dig deep.

“I was out on the Queen K highway in the lava fields, where I let her know that she was in second and that the World Championship was possible if she was able to increase her pace for the last two miles,” Regensburg said.

“She did not look happy to hear those instructions, but she dug down deep, which is so incredibly hard to do after all of the racing and suffering — she is incredibly tough.”

Smith then turned on the afterburners, in a relative sense, so that her mile pace at the end was the quickest it had been throughout the marathon. She clocked 3:36:13 for the final segment to go with 1:08:44 for the swim and 5:43:19 for the bike.

“It was an incredible race,” Regensburg added. “She caught and passed the leader at the very end of the course after ten hours of racing!

“This is yet another incredible feat Karen has added to her extraordinary athletic career. She is the world champion in her age group at the one of the most iconic sporting events on the planet.”

Smith, who is scheduled to return to a hero’s welcome on Wednesday night, thought she was racing for second after the bike, during which the amateurs needed to be on their guard for a ferocious crosswind.

“The ocean swells were larger than normal and the wind on the bike was the strongest I had experienced in the five times I have raced here,” she said. “There were headwinds from mile 30 to 45, then the crosswinds from 45 to 70 were so strong that I saw a guy blown off his bike and into the ditch.

“It was pretty terrifying but I knew to keep low on the bike, which was from experience having raced here before. We endured more headwind on the way back, too; it was relentless. This is Kona and the winds shift all the time, so you have to be ready for it.”

She began the run in second place, six minutes behind the leader but with the benefit of some cloud cover, which was a godsend after the heat of the bike. But she had made only minimal headway on the American before fortunes changed for the better.

“After nine miles, I gained only 30 seconds on the leader, so I was running to protect my second-place position,” Smith admitted. “As the race progressed, I started to feel stronger. My coach told me I was 2:30 back of the leader at mile 22 of the run. By mile 24, I was 1:10 behind. He told me to run like I had two one-mile repeats to do; like a track workout.

“I mustered all of the strength and determination I had and passed her at mile 25. I didn’t look back, as I was so scared she was on my heels. I ran as hard as I could to the finish line, as I would have regretted missing the championship title by a few seconds and have to live with it.”

As it turned out, Smith had no cause for worry, as Hassel trailed home more than a minute later in 10:37:42, with Iris Tiedeken, of Germany, a distant third in 11:08:29.

Smith was the 63rd woman to finish overall out of 621 and 729th out of the 2,187 who started.

One of those starters who expected much better was Bermuda’s Butterfield, who was seventh at last year’s race, and was hoping to break the tie with his illustrious father Jim by going at least one better.

Such ambitions were scuppered by the first mile of the swim when he fell off the lead pack.

He came out of the water 44th in 54:35 and made up 19 places before having to leave the course in pain with about 90 of the 112 miles completed. He had been racing for a little more than 4½ hours.

The 31-year-old two-times Olympian had built his year towards Ironman but was left second-guessing himself over all manner of details — from the modifications to his bike to how hard he had trained.

“I changed one or two things on my bike that were basically sponsorship changes and I probably shouldn’t have done it until 2015,” he said.

“But all the sponsors want their brand represented. I probably wouldn’t have noticed it if my swim was better and there was no crosswind. But when I went into the wind tunnel I moved my arms narrower, which meant the crosswind was more exaggerated and that put more stress on my back.

“I could have been sitting here if I had a better swim and there was less crosswind with a better position than last year.

“The guy who got second this year was fifteenth last year and the guy who was second last year, I think was fourteenth or fifteenth this year. That’s just the name of the game.

“I knew I wasn’t having a great day. At first I thought a top ten would be salvageable if I had a good day. Into the fourth hour, I was thinking top 15, but at the end of the fourth hour, it wasn’t an issue of the result; it was an issue of, ‘Hold on, something’s not right’. And it got worse and worse and worse.”

As a result of failing to finish, Butterfield has had to react by entering a half-Ironman in Australia in five weeks’ time with a view to making up for the points he missed out on in Hawaii.

“I neglected my swim this year and my gymwork,” he said. “Sometimes it’s not noticeable. It’s hard to be perfect in everything. I tried to work on the back end of my bike and back end of my run. I tried to work on weakensses from last year.

“I was in the lead group [of the swim] last year, but right at the very back. This year I fell off the back and I knew it would be a harder race.The back issue was a bit of a surprise. I didn’t have any injuries coming in. It was a mystery when it started to get worse. What I did in 2013 to get better was a lot of long endurace training.

“The problem with doing the same thing two years in a row is that it probably made the things that were weakenesses last year more obvious. I’m not upset for trying it. The pursuit of perfection had its cost. Two steps forward, one step back.

“I tried to go faster in the race by training longer and harder. Maybe I put too much pressure on my back by overtraining, I dont know. In everything you do to go faster, there is also a small per cent chance that it could go the other way.”

The road to redemption for Butterfield begins with the 70.3 Mandurah in Western Australia on November 9.

“It will be a long road to get here next year,” he said wistfully. In five weeks there will be a race that has a lot of points. I’ve got five weeks to work on a bit of speed, which I think I neglected and get the back issue fixed. Then get the bike position back to one that it suitable.”

The other Bermuda representative in Hawaii was Chris Harris, who was 175th out of 247 in the men’s 45-49 age group in 12:02:26 and 1,343rd overall. Harris’s splits were 1:38:06, 6:49:05 and 3:21:44.