Describe the performance of Kon-Tiki's central character as wooden and you've hit the nail on the head. Kon-Tiki was a balsa-wood raft Norwegian ethnographer and adventurer Thor Heyerdahl built in 1947 to prove ancient South Americans could have floated to Polynesia, thus challenging accepted theory that continental drift was west to east.
The raft was rudderless, had a skeletal crew of inexperienced seamen and a patchy radio. It became waterlogged and began to rot well before the 101-day voyage, covering 6300km of ocean, came to its reef-challenged conclusion. Clearly co-directors Joachim Roenning and Espen Sandberg know a good story when they grow up with one.
The pair have made films together since they were 10, culminating in the huge domestic success of 2008 Norwegian biographical film Max Manus: Man of War and now Oscar- and Golden Globe-nominated Kon-Tiki. They grew up in a town near Larvik, where Heyerdahl was born.
"He was a great inspiration, not only because of his inspiring expedition, from the fact he went out and did crazy things no matter what people said, but also because he actually made a movie about it," enthuses Sandberg. "The Kon-Tiki documentary was the only Norwegian movie ever to win an Academy Award. To have a guy from the same kind of place as us winning that was a great inspiration."
Roenning and Sandberg even held auditions for the film at the Kon-Tiki Museum in Oslo, where Heyerdahl's raft is housed.
"We got Thor's son, Thor jnr, to tell us about his father. And Thor's grandson, Olav, also came and talked about his expedition because he actually sailed the same route in 2006. And that's the raft we used in the movie.
"So the movie raft has actually made the voyage."
Shot in six locations, Kon-Tiki is beautiful to behold, even if the crew's conditions were cramped and claustrophobic.
"We were over a month on the ocean and that was just magical," recalls Sandberg. "It was, of course, very tricky because you can't really steer that thing.
The actors actually had to learn how to sail it and make everything work.
"Now I've forgotten about the hardships," he concludes. "I mostly remember the wonderful sunrises and sunsets we got to see out there. It was an inspirational experience."
• Kon-Tiki opens in cinemas on May 16.