'We would have all been dead': The disturbing story behind this photo

Five people enjoying a boat trip in WA have had a lucky escape after they were hospitalised when their vessel began to fill with carbon monoxide.

Andrew Dunn was driving his motor boat from the Royal Perth Yacht Club to Fremantle on Friday night with four friends when he noticed something wasn’t right during their 90-minute journey.

While sailing the vessel, the other four were unresponsive to Mr Dunn’s calls as they approached their mooring at Fishing Boat Harbour.

When Mr Dunn went to check on them, he was unable to wake them.

“They were all unconscious,” he revealed on Facebook.

Andrew Dunn and his wife Nancy. Source: Facebook/ Andrew Dunn

Unaware to Mr Dunn at the time, the four in the upper cabin of his eight-metre motor boat were suffering from potentially fatal carbon monoxide poisoning.

His initial fears were that they’d had their drinks spiked while visiting a bar earlier in the day and quickly moved to open the windows for fresh air – a decision which may have saved their lives.

As he opened the windows, the group slowly began to regain consciousness after several minutes.

One of the friends, Kara Nguyen, was horrified to discover she could no longer see.

“She continued to shake uncontrollably and looked and acted like a zombie,” Mr Dunn explained.

Mr Dunn inside the chamber. Source: Facebook/ Andrew Dunn

They sought immediate medical treatment at the Fiona Stanley Hospital, and as Ms Nguyen’s sight was slowly returning, their brush with death was confirmed when doctors revealed they had suffered from carbon monoxide poisoning.

They were rushed to the hyperbaric chamber at the hospital where they were given pure oxygen in a pressurised room to flush out the carbon monoxide over several days.

While on the road to recovery, they now face an anxious six-month wait to see if they have any permanent nerve or brain damage.

Sole open window saved their lives

Mr Dunn credits his positioning near an open window as to why he was able to remain conscious, frequently sticking his head outside to keep an eye out for unlit sailing markers.

“Had I not occasionally been standing up from my seat and looking through the only forward open window to get a whiff of fresh air I too would have succumbed and we would have all been dead!” he said.

Andrew Dunn and two others inside the chamber. Source: Facebook/ Andrew Dunn

Mr Dunn was later informed his motor boat had fallen victim to the “station wagon” effect, where carbon monoxide travels from the rear of either a vehicle or vessel and filling the vacant space.

While Mr Dunn said he was aware carbon monoxide poisoning was an issue with the enclosed lower decks of boats, he was shocked to discover the more open upper deck was also at risk.

With Mr Dunn’s motor boat having a high bow angle, and all other windows closed due to his guests feeling cold from the elements, the carbon monoxide levels quickly became deadly as the gas drafted in from the rear.

“The danger is having the back canvases off while an insufficient [amount] of the front windows open, especially if you are going slowly, as we were at night,” he explained.

“If you have a tail wind, so no flow from front to back... the vortex flow brings exhaust fumes in through the back, open area.”

Mr Dunn wants his near death experience to be a warning to others over the innocuous habit of closing the windows on the upper deck of motor boats, which in turn prevents a fresh flow of air.

“Hopefully other boaters don't fall foul of carbon monoxide,” he wrote.

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