In the dead of night, as his fuel tanker sailed through the narrowest section of one of the world's busiest waterways, Captain Thiwa Saman was wrenched from sleep and pitched into a waking nightmare.
Three men with guns and swords were banging on his cabin door. Other pirates had already stormed the bridge, seized the duty officer and smashed up the radio and GPS equipment.
Over the next 10 hours, mostly in daylight, the pirates held Thiwa and his 13 crew captive while siphoning off 4 million litres of diesel, worth around $2 million on the black market, to another tanker. They even re-painted the name of Thiwa's ship to confuse anyone searching for it.
Then they vanished.
The May 27 attack on the Orapin 4 was one of a spate of well-organised fuel heists that are reviving Southeast Asia's reputation as a global piracy hotspot.
Since April, at least six fuel tankers have been hijacked and drained in the Malacca Strait or nearby waters of the South China Sea, according to the International Maritime Bureau (IMB), which in mid-June warned small tankers to maintain strict anti-piracy measures in the area.
None of the perpetrators has been caught.
The most recent attack was last Friday, when armed pirates boarded a tanker in the South China Sea, took the crew hostage and stole part of the cargo. That incident is being investigated by Malaysia's Maritime Enforcement Agency.
About a quarter of the world's seaborne oil trade passes through the Malacca Strait, a choke point on the route between the Middle East and the energy-hungry economies of East Asia.
The Orapin 4 was boarded just north of the freewheeling Indonesian island of Batam, a pirate lair for centuries with sketchy law enforcement and unrivalled views of passing ships. Singapore's skyscrapers crowd the distant horizon.
In 2013, piracy attacks worldwide declined 11 percent to 264 reported incidents due to stricter law enforcement in the Indian Ocean off Somalia, according to the IMB's Piracy Reporting Centre in Kuala Lumpur.
But attacks rose dramatically in Indonesia, where 106 of those 264 incidents took place - a seven-fold increase in five years.
The Malacca Strait acquired a reputation as a modern piracy hotspot after another spike in ship boardings in the late 1990s. Back then, the attacks were mostly hit-and-run robberies - the latest outbreak appears to be more sophisticated.
A third of the 106 incidents in 2013 were reported in the last quarter of the year, suggesting "a potential for such attacks to escalate into a more organized piracy model unless they are controlled," said a report by German insurer Allianz.
The IMB has called the rise of petro-piracy "alarming".
"WE ONLY WANT YOUR FUEL"
Thiwa, 66, a Thai national and seafarer for 30 years, said he and his crew were so shaken by the attack that nobody felt ready to return to work. The Orapin 4 was carrying diesel between Singapore and Pontianak in Indonesian Borneo.
Tankers are relatively slow and have low freeboards - the distance from the waterline to the upper deck level - which makes them easier to board.
"Off West Africa, tankers have always been an attractive target for pirates," said Sven Gerhard, Allianz's hull and marine liabilities chief. He suggested this "business model" could have prompted copycat attacks by Indonesian pirates.
Thiwa's crew were forced at gunpoint into his cabin. Some were blindfolded, while others had their wrists bound with plastic cable ties.
"The pirates said, 'We won't harm you. We only want your fuel'," said Thiwa.
Around dawn, he felt the thump of another fuel tanker mooring alongside. Two crew members were taken away to help the pirates open the valves.
Fuel oil or diesel was an attractive cargo for resale because it was in high and constant demand, and its original ownership was difficult to identify, said Gerhard. It was also easy for pirates to go undetected, even in daylight.
"Ship-to-ship onloading and offloading of fuel oil is not unusual," he said. "Many vessels are fuelled by special bunker tankers whilst moored."
The pirates who attacked the Orapin 4 wore the same overalls as Thiwa's crew. "There was no way outsiders could know what was happening," said Thiwa.
By simply painting over a number and two letters, the pirates changed the ship's name to Rapi, which means "neat" in Indonesian.
By 9 p.m., the pirates had siphoned off the fuel and looted the cabins of watches, cellphones, money and other valuables. Then they slipped away into the darkness.
Thiwa and his crew freed themselves and, aided by an undamaged radar, sailed to a port near Bangkok.
"Stealing fuel is a recent trend. It never happened in my time," said Aga, 62, the nickname of a Batam shipping agent and former pirate who still counts many pirates among his friends. "Our targets were only money, the safe, or anything valuable on the ship."
In pirate parlance, thieving valuables is "shopping", said Aga. Stealing fuel is known by the Indonesian phrase "kapal kencing," or "ship (is) pissing".
There were three main pirate gangs active in the area, said Aga. They hailed from all over Indonesia, although Batam boatmen were recruited for their knowledge of local reefs and coves.
Petro-piracy is an organised crime, requiring good logistics and networks to steal and re-sell the fuel.
Local police investigated just one piracy incident in 2013 and arrested five men, said Yassin Kosasih, Marine Police director for Riau Islands Province, which includes Batam.
To catch more pirates, said Kosasih, he needed patrol ships with a greater range, better communications technology - and more fuel.
Aga said pirates choose their targets carefully, aided by live updates on websites such as marinetraffic.com, and by informants at shipping companies or among crews.
On April 22, in the Malacca Strait, pirates stole 2,500 tonnes of marine diesel oil from a tanker. They also took three Indonesian crew in what was initially described as a kidnapping. It is now believed the three men conspired with the pirates.
Stolen diesel is sold to dealers serving Batam's dozens of ports and shipyards for use in trucks, boats or generators, or to black marketeers in Singapore where legal fuel is more expensive, Aga said. It fetches between $400 and $650 per tonne on the black market, so the Orapin 4's cargo was worth anything up to $2.2 million.
Pirates fear the naval ships that patrol the Strait, said Aga, but still usually manage to outmanoeuvre them.
"Indonesia is the world's largest archipelago, with thousands of islands," said Jarek Klimczak, a master mariner and senior risk consultant at Allianz. "The proper control and monitoring of all of its waters is nearly impossible, even for an advanced navy. And Indonesia's navy is far from advanced."
On June 14, off Malaysia's eastern coast, pirates boarded a Honduras-registered tanker called Ai Maru carrying 1,520 tonnes of marine gas oil. The Malaysian coastguard and the navies of Malaysia, Indonesia and Singapore dispatched six ships.
They found the Ai Maru less than five hours later - a relatively swift response - but the pirates had already fled along with a third of the fuel.
Two years ago, in Malaysian waters, pirates boarded and robbed another oil tanker captained by Thiwa Saman.
Then, the pirates had carried only knives. Now they had guns, too. "My family don't want me to go back (to sea) because it's too risky," he said.
By Andrew R.C. Marshall