One of the victims said he was punched 4-5 times by Rawiri who was the front seat passenger.
The tourists were unable to identify their attackers but one had recalled most of the number plate of the robbers' vehicle. The vehicle was later identified as Bridger's mother's car.
Rawiri, who was jailed for two years in January last year, gave evidence against Bridger at his trial, and told the court Bridger was the instigator of the attack.
Bridger's lawyer Tony Balme told Judge Peter Rollo that his client accepted there had to be an uplift on the end sentence due to his prior convictions, and the fact that he was on parole conditions at the time of the robbery.
But Bridger does not accept the jury's verdict, Mr Balme said.
Judge Rollo said Bridger's sentence had to be longer than his cousin's because it was a serious aggravating factor that he still subject to parole conditions for 2009 conviction for wounding with intent to cause grievous bodily harm.
The judge told Bridger that while it was his right to maintain his innocence, as the trial judge he was entirely satisfied the jury had reached the correct verdict.
Bridger has been ordered to pay $1500 reparation to his victims on his release from prison.