Illawarra rugby's so-called invincibles Shoalhaven have qualified for their third straight grand final after a gritty 10-7 win over Kiama in Saturday's major semifinal at Shoalhaven Rugby Park.

The Shoals are now just one win away from creating history and joining a select group of Illawarra District Rugby Union clubs to win three titles on the trot.

Though the minor premiers were made to work extremely hard for their 38th win on the trot.

Shoals started brightly enough and took a 7-0 lead when Keiran Brandon converted his own try after 23 minutes of the game.

But three minutes before halftime the James Patrick-coached Kiama hit back with a try to Cows No 1 Atu Taufa. Robert Siteine added the two points to see the teams head to the sheds locked at 7-7.

Only three points were scored in a tough and tight second half, and they came from the boot of Jack Watts, who kicked a penalty goal 15 minutes into the second half.

Watts missed another penalty goal later in the half but the one he converted was enough to secure a win for Shoalhaven, much to the pleasure of player-coach Will Miller.

"We kicked one of the penalties, which was good, it was a tough game," he said.

"We see a few niggles and little injuries out of it but hopefully they're all gonna be good by grand final time."

Miller was hopeful his team would improve and play better in the grand final but wasn't surprised how well Kiama played.

'They offered a great game like I thought they were going to," he said.

"They're an excellent team and they're a very tough team and they're gonna work hard for each other.

"You can't be expecting to just blow teams off the park every week, especially in these type of games where it's the teams that finished one and two playing off against each other.

"But from our point of view it was good to see that we could win gritty when we needed to.

"They were throwing a lot at us at the end there too and put us under a lot of pressure and we put ourselves under a lot of pressure as well but it was good to be able to keep defending and keep standing up for each other and work hard for each other and have that grit."

Miller added the win itself was most pleasing because it secured the Shoals a shot at another title.

"We've never been that worried about protecting that undefeated tag," he said.

"I think everyone's goal here is just to focus on the next games we've got, and today was a chance to progress to another grand final.

"Now we got a chance to win a competition, which on its own is an amazing achievement. So we've just got to focus as much as we can on ourselves.

"We'll see who we're up against in the decider soon enough."

Having secured their grand final berth Shoalhaven will have next week off but not so Kiama, who will play the loser of Sunday's minor semifinal at Ocean Park between Campbelltown and Camden.