''If tourists continue to be treated like this, it's bad for Thailand's reputation,'' said Anusorn Sale, the former president of the Bang Tao Jet-Ski Association. ''Phuket's Marine Office 5 and other authorities should do their jobs properly for a change.''
Khun Anusorn escorted one of the ripped-off Chinese tourists to Cherng Talay Police Station on the weekend to lodge a report about the extortion scam.
Scams involving jet-ski operators continue on Phuket but only a small number are ever made public so local authorities acquiesce and are able to pretend there is no problem.
The weekend incident began when six Chinese tourists hired four jet-skis at Bang Tao beach - further south, Patong beach has more jet-skis and more scams.
''Within five minutes, two of the jet-skis had crashed,'' Khun Anusorn said. ''The jet-ski operators immediately demanded 200,000 baht in compensation.
''By my reckoning, the damage to the fibreglass hulls would have cost 20,000 baht to repair. Insurance would cover that.''
Khun Anusorn said that jet-ski operators these days are obliged to have contracts in English, Chinese and Russian but the Chinese were made to sign a contract in the Thai language.
''The Chinese were told 'If you don't pay in cash immediately, we won't let you leave the beach.''' Khun Anusorn said.
''They then allowed one man to go to an ATM while intimidating the other five to stay on the beach.''
The man returned with 99,800 baht, which the jet-ski operators accepted as a down-payment, telling the Chinese they could go and pay the rest of the money later, Khun Anusorn said.
''I reckon damage to the fibreglass bodies of the jet-skis would take 20,000 baht to fix,'' he said.
It's not clear whether the operators also claimed on insurance, which covers each machine to a maximum of 50,000 baht.
Jet-ski operators often extort a ''time out of the water'' sum of 16,000 baht or 17,000 baht, calculated at 3000 baht for up to five days the machine might need repairs.
Often, having paid this sum, victims see the jet-ski back in the water the following day.
Khun Anusorn took one of the tourists to Cherng Talay Police Station yesterday but there was a problem with his Chinese being understood.
''When Phuket Marine 5 Office, which oversees Phuket's jet-skis, was contacted about this incident, an officer said: 'This case hasn't reached the embassy yet. Let the embassy complain, then we will check it out.'''
Khun Anusorn said he believed Marine Office 5 failed to properly oversee the jet-ski operators on Phuket.
Chinese authorities have previously warned that official action will be taken to warn their tourists about jet-skis and other dangerous rip-offs unless authorities on Phuket prevent scams and uphold the safety of tourists.
All of Phuket's jet-skis were supposed to be phased out over a period of seven years but compromises by a succession of governors leaves hundreds of them still operating today at most of Phuket's best swimming beaches.
The scammed Chinese tourists were due to fly out today, Khun Anusorn said.