SINGAPORE - An underwater ship maintenance firm and its assistant diving supervisor were found guilty on Monday (Feb 3) of offences linked to the death of a diver who was killed after he was sucked into a pipe opening while underwater.

Mr Kwok Khee Khoon, 36, also known as Edmond Kwok, was working for Underwater Contractors when he was killed at the Eastern Working Anchorage in waters near Marina South Pier, on June 4, 2014.

The tragedy occurred after pumps in a sea chest in which divers were working were not completely shut down.

The safest way of carrying out such work underwater is to dive when pumps are shut down.

Earlier news reports noted that a sea chest is meant to suck in seawater to cool the engines and generators on board. If switched off, a ship would not be able to power its systems, lights, air-conditioners and other components that require electricity.

District Judge Jasvender Kaur found Underwater Contractors and assistant diving supervisor David Ng Wei Li, 36, guilty of offences under the Workplace Safety and Health Act.

She convicted the company of failing to take measures necessary to ensure the safety and health of its employees at work. Ng was found guilty of performing a negligent act that endangered the safety of others.

In their submissions to the trial, Ministry of Manpower prosecutors Delvinder Singh and Shanty Priya said the company Sleipner Shipping had engaged Underwater Contractors to carry out survey works on the MV Frisia Kiel.

Mr Kwok was part of a group of six divers working at the vessel's bow thrusters when he was seen being sucked into the pipe opening.

The prosecutors said: "Several attempts by the others divers to pull the deceased away from the pipe orifice failed. The deceased was finally brought on board the first workboat after the starboard sea chest pump was finally shut down."

Mr Kwok was motionless and paramedics pronounced him dead at around 7.40pm that day. He was later found to have died of traumatic asphyxia.

The prosecutors said that there were several measures that Underwater Contractors had failed to take that were "reasonably practicable to avert the risk of a diver being sucked into the pipe orifice".

They added: "It is clear that there is no dispute what the safest manner of performing the diving works was on (that day), which was to completely shut down the pipes in the sea chest that the divers work in ... it is clearly not in dispute that the safest way of performing the diving works ... was not followed."

The court heard that the defence's case rested on the assumption that a member of the vessel's crew had increased the suction of the pumps without notice. The prosecutors said that there was "no credible basis" for this assumption.

They told Judge Kaur: "The fact that the deceased was sucked inside the starboard sea chest was the result of the accused company's failure to identify and mitigate the obvious risks associated with working inside a sea chest when the sea chest pumps were not shut off."

Ng had instructed the divers under his charge to perform underwater survey works even though he was aware that the pumps were in "reduced flow" but not shut off.

He and Underwater Contractors will be sentenced on April 9.

A company that fails to take measures to ensure the safety and health of its employees can be fined up to $500,000.