The Wellington man who climbed a Len Lye sculpture only for it to come crashing down under his weight says boredom and an encouraging crowd were behind the stunt.

But historian Roger Horrocks, who was Lye's personal assistant in the final year of his life, said the artist would have been "deeply hurt by the sheer idiocy" of the person who saw it as just a climbing frame - and not a work of art.

Hunter Macdonald said he was "bored out of my mind" while walking along Wellington's waterfront, when he came across the Water Whirler sculpture – which cost about $300,000 at the time of installation in 2006.

SUPPLIED Hunter Macdonald has been charged with wilful damage after publicly admitting snapping Len Lye' Water Whirler sculpture.

In a video interview supplied to Stuff he said: "I decided to stop and sort of attempt some sort of gymnastic, acrobatic stuff on the sculpture".

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Macdonald said he had no idea that Lye, "who is clearly a big deal" had actually done the work.

SUPPLIED Hunter Macdonald's $1000 reparation will pay for a sign warning others against climbing on the scupture. Pictured: Macdonald during the incident.

"Obviously that is his work, his art, so obviously I apologise for defacing that, that wasn't my intention. To the people of Wellington, it's such a beautiful city and everyone sort of takes pride in the city, so I do apologise to them."

Wellington City Council spokesman Richard MacLean said it was too early to estimate how much the fix would cost, but it looked likely to be covered by insurance.

"We'll have to get structural engineers and other experts to have a close look at the damage to see whether the broken pole can be repaired or whether it has to be replaced."

It was too early to say if the sculpture's motors had been damaged, he said.

A Police spokeswoman said Police have been in touch and would take a statement from him on Tuesday.

Macdonald said after falling from the sculpture he struggled to the nearby rocks.

SUPPLIED Hunter Macdonald was injured when the Len Lye Water Whirler sculpture, worth about $300,000, snapped.

"At that point I'd realised that I'd made a serious mistake."

He said he couldn't really fathom the cost of fixing the sculpture.

"They were throwing big figures at me, 'that's a hundred thousand dollars, that's taxpayer money', figures that I couldn't even fathom. I'm never going to receive a pay cheque of that magnitude."

He said he expected to face repercussions.

Horrocks said the incident showed "complete disregard" for art.

"[Lye] would've been absolutely devastated, not just by the damage to the sculpture, but mostly to the act.

"The face that the person thought it was some kind of game and also for someone to make it about himself."

Horrocks said his own initial reaction was "one of great anger".

"He would be hurt by it ... he spent his entire life making art and respecting art as something intensely beautiful."

The work was unique and as a kinesthetic sculpture, every movement it made was different.

The Water Whirler was installed in Wellington 2006, with installation pushing the final bill up to $1 million. In 2016 it was turned off for repairs.

Horrocks said this month, the sculpture was scheduled to be returned to full operation.

"Now it's going to be months."

The cost to fix would be six figures, he said.

It would require specialist knowledge to fix the wand, which was extremely complex.

Horrocks said the work to fix the sculpture, likely by the Len Lye Foundation, would be time taken away from creating their own art.

It was a New Zealand-wide problem that public art was not respected, he said.

"There's people in the community that have no understanding that sculptures are valuable and need loving care."

Len Lye has been said to be more well known overseas than he was in his home country of New Zealand.

His career as an experimental filmmaker, poet, painter, and kinetic sculptor saw him lauded by his peers, and his work is in some of the most renowned galleries in the world.