Watson, 40, from Wingham, will be tackling the 3.8km swim, 180km bike and 42.2km run for the first time. He's been competing in triathlons for about three years after following his children into the sport.

While fully fit now, Watson said the niggling calf strain has been a nuisance.

"I thought it was right then it reared its ugly head again,'' he said.

To counter this Watson chalked up more kilometres training on his bike.

"I was probably doing about 400km a week when my leg was injured,'' he said.

"I did have a time in mind that I wanted to do, but the injury has thrown that out a bit. I'll just be happy just to finish.''

Watson was mates at school with former ironman triathletes Jared Brauer and Ross McRoberts and says going in the race was something he has always wanted to do.

However, it wasn't until his kids started racing with the Forster Tri Club that he really started chasing his dream.

Rugby league with the Wingham Tigers dominated Watson's earlier sporting life. As such he had no real form as a longer distance runner or swimmer.

"I was in the swimming club when I was at school,'' he explained.

"But I wouldn't have swum any further than 100m.''

After joining the tri club he began training with the likes of Richard Sewell and Rhett Pattison, working particularly on the bike and in the pool.

His CV now includes half ironman races at Port Macquarie and Forster. He completed the Forster course in around 4 hours. Racing in the half at Port Macquarie also gives him some idea of the course he'll tackle this weekend.

Watson's worked closely with Sewell in his preparation for the ironman. He's confident that he's ready for whatever Sunday throws at him.

"I think the last 15 to 20km of the run will be the hardest,'' he said.

Watson will race in the competitive 40-45 age division.

"I told my wife that going in this is my 40th birthday present to myself,'' he laughed.

The race is a qualifier for the world ironman to be raced at Kona, Hawaii, later this year. However, Watson has no delusions about earning a start in that race, regarded as the toughest ironman triathlon on the planet.

"Not this time anyway,'' he said.

And he admits that he doesn't know when and if he'll line up in an ironman race again.

"It'll depend on how I pull up after this week,'' he said.

"I'll access it then. But training does take up a lot of time away from the family. The timing of the race fits in perfectly because it's on before my three kids really get stuck into winter sport.''

He'll have some support on Sunday with his wife and children going to watch.

"They'll be at the finish line. That'll be good,'' he said.