Grade 4 teacher Naomie O'Loughlin said pupils had been taking part in the challenge for four years in a row as part of their STEM program, and would later go on to race their creations in the Soggy Bottom Cardboard Box Boat Regatta.

"It's the best way to start off the school year," she said.

She said the practical project got pupils to both use their imagination and their analytical skills to measure, fold, and think about water buoyancy to create the perfect boat.

"They all made predictions about what was going to happen to their boat, they all wrote them down in their STEM book. We video it so now they can go back on Monday and watch those videos and work out what went wrong," she said.

Boat testers Samantha Strong and James van der Aa said their boat faired OK but did end up sinking.

Samantha said the biggest lessons she learned while making the boats were teamwork and communication. James said it he learned how important it was to build things with a good structure.

"I can't wait for the real race," Samantha said.

"It's so much fun and I think every school should do this."

The Soggy Bottom Cardboard Box Boat Regatta is run by the Rotary Club of Youngtown with the Rotaract Club of Tamar Valley.

The regatta will take place on March 1 at Waverley Lake.

For more information, visit soggybottomregatta.org.