The side will be the first from the Flinders Field-based club to play in a Group Seven Rugby League under 18s decider, which is massive achievement considering they couldn't field an under 18s team four years ago.

And split an under 18s side in 2019, due to lack of numbers.

"It's been a long process getting the boys program to where it is today," Towle, who's coached at the club for more than 10 years, said.

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"We've had a strong junior base for years but unfortunately we lost them after their international ages (under 16s) because we couldn't field a team and players went elsewhere in Group Seven.

"However, thanks to the hard work of committee members, led by Scott McLaurin and Matt Poort, the club has been able to develop a clear pathway from the juniors into the under 18s and then into grade, which the Reh brothers have assisted with this season.

"Just playing in a grand final lays the foundations for future years, as it gives everyone confidence we are heading in the right direction.

"Then if we were to go on and win our maiden premiership, it would be absolutely massive for the whole club."

The Rays will head into the decider unbeaten, having won eight and drawn one of their regular season matches - as well as defeating Kiama 24-20 in golden point during the grand final qualifier.

"Considering how frustrating the start of the season was, after starting training and December and having the year impacted by COVID-19, the boys have responded really well," Towle, who's side mostly comes from Hamish McLaurin's victorious under 16-1s side in 2019, said.

"Despite the changes in our training methods, the boys haven't missed a beat and only drew that one game with Milton-Ulladulla [14-all on August 14]."

One of those wins came against cross-town rivals the Shellharbour Sharks [20-14 on August 23] - who the Rays will face in Saturday's decider at the nest.

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"It was a tough game against Shellharbour that day and we expect it to step up a notch with a premiership on the line," Towle, who highlighted the play of Jack Bostock, Trey Barlow, Colby Smith, Will Starling, Nat Marland, Jee Ross, Bodee Towle and Dane Nelson in 2020, said.

"We can't rest on our laurels on Saturday, as a grand final is a clean slate and everything we've done up to this point means nothing.

"It's obviously a massive rivalry and I'm sure there will be plenty of feeling in the contest.

"The keys to us winning is to play to our strengths which are through our dangerous and evasive spine before creating space for our outside backs to score.

"We know the Sharks have got a big pack, so it's up to our nimble forwards to outwork them.

"With plenty of players in our squad who have played at representative levels, I'm confident the big stage won't get the better of them and we can finish off the season on a high."

While the Stingrays have only played one match the past three weeks, their opponents Shellharbour have played three, which co-coach Jay Efaraimo believes works in his side's favour.

"There's no doubt we've done things the hard way but has suited us and helped us appreciate where we are now," Efaraimo, who has been coaching alongside Grant Galway the past two seasons, said.

"Obviously the Rays have been the standout side all season and deserve to be where they are but all of us have thoroughly enjoyed our finals campaign, which has allowed us to work on a couple of things such as marker defence and tightening up our line.

"When we travelled down to Milton-Ulladulla two weeks ago, we probably played at 65 per cent of our capabilities, which went up closer to 75 per cent against Kiama - which was probably our best performance this season.

"We are starting to click on all cylinders but know we need to raise our performance to at least 85 per cent this Saturday and I'm confident we can."

The 2020 season has represented one of significant turnaround for the Ron Costello Oval-based side, after winning just six games last season.

"Last season was understandably tough on the group, with most of them being younger," Efaraimo, who's worked alongside Abed Atallah and the Sharks first grade set-up in the past, said.

"However, with a core nine players remaining, it helped set us up for this season, which, at some points earlier in the year, might not have happened because of COVID.

"Once we did kick-off, it looked like the season was going to be a sprint and whoever was the fittest and avoided injuries the most was going to come out on top.

"It's turned into a grind, with our boys embracing every challenge that's come their way.

"The amount of growth the boys have done not just this season but also last has been incredible and a testament to all their hard work - this grand final spot is a reward for all of that and all the boys know they deserve to be here."

However, the young Sharks know the job isn't done and their final task of the season comes in the shape of cross-town rivals Stingrays.

"The way it's worked out with an all-Shellharbour final is great for the players, families and the group as a whole," Efaraimo said.

"Most of these boys have played footy, Oztag and touch with and against each other for a number of years - not to mention socialising off the field.

"It obviously adds spice to the grand final, with bragging rights also on the line."

If they are to win their first under 18s premiership since 2014, Efaraimo knows where his team need dominate.

"The Rays, who will go in as favourites, have got a stack of dangerous outside backs, which make it super important for ours to aim up," Efaraimo, who's club also won four Illawarra under 18s crowns from 2009 to 2013, said.

"However, the keys for us winning will be in the middle of the park with our forwards.

"With players such as Noah Galway, Drever Burdis, Clive Brett, Ethan O'Connell, Aiden Moule, Jayden Dolenc, Kyron Ebbs and Darcy Phillips at our disposal, our pack is as strong as any in the competition and if they can dominate the ruck and it will give us a huge boost on Saturday.

"If we do that, Grant and I know the boys could get over the line, which would be a fantastic achievement for the club and one we'd all be proud of."

The under 18s grand final kicks off at 11.30am on Saturday at Centenary Field.