Kiwi submarine closes in on world speed record

A Kiwi-built, human-powered submarine has made a splash in an international race, falling just a knot short of a new world record.

The 3m-long fibreglass Taniwha, the creation of a team of researchers and students from Auckland University's Auckland Bioengineering Institute (ABI), turned heads when it hit the water at the 13th International Submarine Races, held in the US last week.

Just a year after its debut, the sub finished in the top position for a single-person, non-propeller submarine and earned an honourable mention from the judges in the event's innovation category.

And in the spirit of record-breaking motorcyclist Kiwi Burt Munro, the team managed to push the little craft to a top speed of 3.65 knots.

While this equated to only 1.88 metres per second - a brisk walk - a speed just one knot faster would have beaten the world record for a submarine of its quirky kind.

The sub, which weighs just 60kg and painted like a Taniwha with fierce teeth decals, is driven by a pilot who remains completely submerged in water and breathes oxygen through scuba equipment while he pedals it.

The pedals operate fins that propel it through the water for the race, demanding plenty of power from the driver and optimal buoyancy and control from the design.

Last week's race was held in a 6m-deep, 100m stretch of the David Taylor Model Basin, which forms part of the Naval Surface Warfare Center in Carderock, Maryland.

Pitted against it were subs from Europe and the US - and the Taniwha performed well enough that it could give propeller-driven boat crews a run for their money.

"I think we did really well," said Associate Professor Iain Anderson, who built the sub with his biomimetics students.

"The race organisers were all very complimentary about it and they thought it looked really good."

Achieving a good result and completing 10 of 11 runs was made all the more special by the sub being the event's first-ever entry from this side of the world.

"We had a whole hemisphere on our shoulders."

The challenge now, he said, was to get that elusive extra knot ahead of its next race in 2016.

"That's easier said than done, but I think with some intelligence we could find the speed we need."