Presented by Professor Heinz Wolff
Fourth Heat: The Long Tide On Brancaster Sands in Norfolk the teams have only a few hours to build a wave-powered machine to hoist a flag.
The incentive to work fast is the incoming tide which will soon surround the teams, sets and all.
When the starting gun fires, they are already at sea as they carry out frantic last-minute changes to their stranded contraptions. Guest judge
Professor Ian Fells Director ALEX LAIRD
Producer CHARLES HUFF