Mr Elvey said there was no restriction on the size of the boat - ''you just had to be able to get in it''.
It did not matter if the boat sank during the race but the crew and 70% of the cardboard had to make it back to shore to finish the course.
He said the event was designed to encourage creativity and to get families working together as a team, ''because not many of these kids build these boats on their own''.
''It is also a chance for young people to show off, show what they can do, or sink badly.''
The boat race was preceded by the Polar Plunge, where people in fancy dress jumped from the lake jetty.
Both events were supported by Lakeland water sports and the race raised money for Kahu Youth through a gold-coin donation.
kerrie.waterworth@odt.co.nz