A dope smoker who was angry his cannabis stash had been stolen used a large machete to threaten two charity workers, stealing their vehicle and performing burnouts in it, in a bizarre bid to “calm himself down”.

The NT Supreme Court Justice Trevor Riley said Gibson Mamarika, 28, who pleaded guilty to having robbed his victim and unlawful use of a motor vehicle as well as causing damage to it, performed the “impulsive” car-jacking at Bikerton Island west of Groote Eylandt on March 24, using a 45cm long blade to intimidate two Aminjarrinja Enterprises workers, who were on the island fixing up houses.

Holding the machete above his head in a threatening manner, Mamarika yelled “get out of the car” at the charity workers, before taking their Toyota Hilux for a joyride around the Bikerton Island community.

Mamarika performed a series of burnouts and donuts in front of community members for around five minutes before crashing the vehicle into a fence and calmly walking away.

When the charity workers located their damaged vehicle later that day, Mamarika approached them and said he was sorry.

He was arrested two days later at Bickerton Island Airport.

The court heard Mamarika, who has never held a driver’s licence, was upset someone had stolen his cannabis and was desperate to obtain more, but when he was unable to do so, thought stealing the vehicle and taking it for a joyride would “settle himself down”.

Mamarika’s lawyer said he was also suffering stress at the time arising from the breakdown of a 10-year relationship, his mother having cancer and his daughter being taken to hospital.

Justice Riley said the explanation Mamarika provided for committing the crimes was “not a rational excuse for your offending”.

“It is not the case that you were under the influence of any drug at the time of the offending, although you do say that you wished to obtain cannabis to calm yourself down before taking the bizarre step of stealing the car,” he said.

“You were upset because someone had stolen your cannabis … you said you were desperate for cannabis to settle yourself down, and you thought you would take a joyride to settle down.

“To steal a car to take a joyride to ‘settle down’ is both immature and self-indulgent conduct.”

The court heard Mamarika had a lengthy criminal history amounting to nearly 30 previous offences, had breached bail on four occasions and had breached the terms of a suspended sentence eight times.

Justice Riley said he would partially suspend Mamarika’s sentence if he agreed to attend the Venndale Rehabilitation Centre in Katherine when he was released from prison and take part in a six-month program to address his cannabis use.

“I have concerns arising from your history of failing to comply with court orders … however, I think it appropriate to give you a final chance, a chance to demonstrate that you can comply with court orders and undertake rehabilitation,” he said.

“It seems to me that that gives you the best opportunity to turn your life around, although it is getting very late for you to do that.”

He sentenced Mamarika to three years and four months in prison, to be suspended after eight months provided he attended the rehabilitation centre when released.