The self-styled daredevil who destroyed a $300,000 sculpture on Wellington's waterfront suffered a brain injury that came "dangerously close to being fatal" his lawyer says.

Hunter Laurie Browne Macdonald, 28, appeared in the Wellington District Court today for sentencing after he was filmed climbing and snapping the Len Lye Water Whirler last year.

Macdonald - who has offered to pay for a larger sign by the sculpture warning people not to climb on it - was on the waterfront near Frank Kitts Park on October 8 when he began doing "gymnastic-type movements" on the sculpture, according to a police summary of facts.

He climbed the pole until it bent over, suspending him above the water, and then snapped, sending him plunging into the harbour.

Defence lawyer Carrie Parkin said Macdonald has suffered significantly since the offending, including suffering a "substantial brain injury".

Macdonald lost his job as a result of the ensuing publicity and had been the subject of ongoing criticism from the public and of "some fairly malicious bullying over social media".

Parkin described the offending as "a few moments of stupidity which very much could have cost him his life".

In an explanation to police, Macdonald said he was trying to climb out to the end of the pole and intended to climb back again, "believing this would look impressive to the crowd".

Another "motivation" was that he had never seen anyone else climb it, and thought he would be the first.

Macdonald earlier publicly admitted to being the person in the video shared across social media, which showed the sculpture bending as he climbed it, until it snapped at the base and hit him on the head as he fell into the water.

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He was taken to hospital with a gash on his head after the incident.

The court today heard the cost of dismantling the sculpture and sending it to Christchurch for repairs would be completely covered by Wellington City Council's insurance.

The estimates for repairs were at least $42,000 to $51,000.

Macdonald has offered to pay for a larger sign to be put in place warning people not to climb the sculpture.

Judge Jan Kelly said Macdonald had eight previous convictions, mainly related to alcohol and driving matters. He last appeared in court in 2015.

According to a pre sentence report, Macdonald said he had previously felt "invincible" but no longer felt that way after suffering significant injuries, Judge Kelly said.

He apologised for his offending at a restorative justice meeting and it was agreed he would pay for the new signage.

Judge Kelly sentenced Macdonald to 150 hours of community work and ordered him to pay $1000 reparation.

At the time of the incident, Wellington Mayor Justin Lester labelled the behaviour "an act of utter stupidity".

"I encourage people to think twice about doing something this silly.

"I've seen some pretty silly acts in my time ... this was certainly a very negligent act of a public display of bravado which really backfired quite seriously, but he shouldn't have been there in the first place."

The Len Lye sculpture had been undergoing maintenance following damage caused during the Kaikoura earthquake when the sea water got into it and fried the electrics and was due to be back in action this month.