Richard Hedley, the RBAI coach was a relieved man after his side qualified for the Danske Bank Schools' Cup final on March 18.
"I'm glad to be through that as Ballyclare put us under a lot of pressure and in consequence we froze on occasions," said Hedley.
"One thing especially pleasing is the fact that we didn't concede a try. When they attacked we managed to scramble our defence back without giving away penalties.
"It is a big disadvantage coming into a game as favourites as I feel the side felt the pressure. We need to improve in a number of aspects of our game so there is a lot of work to be done over the next two weeks."
Yes, Inst were rather flattered by their winning margin as Ballyclare created the more opportunities but basic errors prevented them from scoring any tries.
The Belfast team had a strong centre combination of Nathan Brown and Rory Bell who always made a few metres when in possession but the Ballyclare out-half Jack Irvine had a brilliant game.
His positional play, defensive qualities and accurate kicking kept his team in the tie even when they were behind.
The first scoring opportunity came after eight minutes when Ballyclare flanker Matthew Kerr found a hole in the opposing defence and raced in to within ten metres of the line but a penalty gave Inst relief.
The first try came following a high kick ahead by Fraser Wright which was fielded by Rory Campbell. The ball was then swung across the backs for Bell to break through and link with winger Ian Jones who crossed in the corner.
A fantastic break from Irvine set up another Ballyclare chance and he seemed surprised to be out on his own so had to slow down for cover to arrive which it did in the form of James Beattie but unfortunately the full-back put a foot in touch before going over.
A good clearance kick from Inst scrum-half Connor Young followed but then Ballyclare were awarded a penalty 35 metres out.
Irvine had to wait a couple of minutes for a kicking tee but with none forthcoming he just lifted the ball and calmly and confidently dropped kicked the ball between the posts.
A golden opportunity for Ballyclare followed shortly afterwards when Irvine found another gap and raced to the 22 but the final pass was dropped with the line at the mercy of the winger. Undeterred the Ballyclare forwards with David Lawther, Michael Kirk, Michael Mooney, Jordan McKinstry and Jonny Darling much in evidence kept up the pressure throughout but the team's finish was missing.
When called upon Inst had to defend stoutly and this they did, biding their time waiting for their chance.
Six minutes into the second period and a missed tackle allowed Inst centre Nathan Brown to touch down before Irvine kicked a second penalty. After fourteen minutes Campbell added a penalty from 33 metres to make it 13-6.
Ballyclare looked dangerous on the break and they brought play up the pitch again.
Irvine missed with a penalty from outside the 22 but made amends a minute later from in front of the posts. They were now back within a try again but the issue was put beyond doubt after 28 minutes when Bell weaved through for his team's third try.
Ballyclare coach Daniel Soper said: "I feel they all played pretty well although we had a clear plan but it was not adhered to. We created numerous chances and put away none while our opponents only had a few but capitalised.
"I told the boys at half-time to just hold on to the ball and don't rush things but I think they forced it a bit, thus making errors."
Inst coach Hedley is looking forward to the final, saying "If Methody come through then they will start favourites which will suit us fine and reduced some of the pressure.
"By then we would hope to have second row Cameron Magee and a fully fit Ben Davis who was on the bench today. Our only concern would be flanker Andrew McGrath who suffered ham strin problems and had to be replaced."