In the aftermath of the sudden sinking of the £30 million Bayesian superyacht, experts say there is still a slim hope for the six missing passengers.
The ship sunk suddenly just before 5am on Monday morning after being struck by a freak waterspout while it was anchored off the coast of Porticello in Sicily.
While 15 passengers have been rescued, those still missing include the British tech tycoon Mike Lynch, his 18-year-old daughter Hannah and a boss at Morgan Stanley.
Despite having disappeared 50 metres beneath the waves almost three days ago, experts say there is a chance that the missing passengers could be alive.
Speaking to MailOnline, scientists explained that their best hope of survival would be within air pockets on the sunken ship – but rescuing them could prove tricky.
The superyacht Bayesian sank suddenly in the early hours of Monday morning. But experts say some of the missing six passengers could still be alive within an air pocket
As the search for the missing passengers goes into its third day, rescue divers are continuing their efforts to reach the cabins in the hope of finding a survivor.
Yesterday, divers used specially made jacks to smash through a 3cm-thick porthole to gain access to the hull of the vessel.
Their hope is that at least some of the passengers may be trapped in their cabins but still alive within pockets of air.
Nick Sloane, an engineer who worked on the Costa Concordia salvage operation a decade ago, told Sky News that search teams had ‘a very small window of time to try to find people stuck inside with hopefully an air pocket.’
Air pockets are formed in sinking ships as water fills up the hull and pushes air up towards the surface.
Just like placing an upturned glass into a bowl of water, if that air is pushed into an enclosed spac,e it can form a bubble which persists at almost any depth.
Mr Sloane added: ‘If the yacht is on its side, it might have more air pockets than if it’s upright.
‘She’s got quite a large keel, and that will deflect and put her on her side, I’m sure.’
Provided that the air pocket is large enough, a trapped passenger might be able to float or stand in their cabin with enough air to breathe for several days.
The superyacht owned by British tech tycoon Mike Lynch sank after being struck by a powerful water spout which may have flooded the ship through an open window or hatch
Giving search and rescue teams hope is the fact that there have been cases in which people have survived and been rescued from air pockets.
In 2013, a tugboat sunk 30m to the seabed about 20 miles (32km) off the coast of Nigeria, killing 11 out of the 12 crewmembers.
However, the ship’s chef, Harrison Okene, 29, managed to find his way into an area with an air pocket where he survived for three days until divers found him in the wreckage.
Mr Okene not only survived the ordeal, but did so with very limited health complications and went on to become a commercial diver.
If any of the Bayesian’s passengers are trapped in similar air pockets, this case presents the best possible argument that their rescue is still possible.
In 2013, a Nigerian chef was rescued by divers after having been trapped inside an air pocket 30m below the surface for three days
Dr Doug Watts, dive and hyperbaric medicine expert and medical director of DDRC Healthcare, told MailOnline: ‘The question is whether someone could survive for three or more days in an air pocket at a depth of 50m.
‘And the answer, as demonstrated by the case of this Nigerian chef, is yes.’
However, there are several critical factors which will determine whether anyone trapped in an air bubble can survive.
The first potential issue is the temperature of the water in which the passengers are trapped.
At a depth of 50m, the water will be significantly colder than at the surface which could be fatal after three days of exposure.
The next major factor is whether the air pocket is large enough to allow the passengers to breathe for three days.
Dr Watts says: ‘The air mix is probably compatible with life just about, but there needs to be enough that you don’t get CO2 poisoning.’
Contrary to popular belief, it is not the reduction in oxygen levels but the build-up of C02 from the survivor’s breath that will be the biggest danger.
As the passenger breathes, they slowly add more and more CO2 to the air.
At about a 10 per cent concentration of CO2, the air will become toxic leading to convulsions, loss of consciousness, and death.
That means someone needs to be trapped in a large air pocket where the CO2 concentration won’t reach dangerous levels.
Finally, any rescue attempt will need to consider the effects of spending up to three days at a depth of 50m.
As the air pocket forms in the ship, that air will be compressed by the surrounding water to a pressure greater than 70 lbs per square inch.
That pressure will force nitrogen in the air to dissolve in the survivor’s bloodstream, which could cause dangerous complications during a rescue mission.
Dr Watts compares the conditions of the passenger’s body to a bottle of Coke.
Harrison Odjegba Okene (second left) poses inside a decompression chamber with members of the DCN Diving team who saved his life. Due to the saturation of nitrogen in his blood, Mr Okene needed to decompress for three days after his rescue
Rescue workers look at the plans of the Bayesian as they organise a search operation for six people who are still missing after the superyacht sank. If any are trapped within air pockets there is a chance they could be rescued
The liquid in the bottle is saturated with dissolved gas, but since it is pressurised you can’t see any bubbles.
‘But if you release that pressure, you can see those bubbles coming out of solution. It’s the exact same thing that happens with a diver,’ Dr Watts says.
Since any survivor’s blood will now be entirely saturated with nitrogen, they will need to be brought to the surface very slowly in order to avoid bubbles forming in their blood, in a condition known as the bends.
In the case of the Nigerian chef, rescue crews brought the survivor to a diving bell typically used by commercial divers to live for days at a time at extreme depths.
The pressure was then slowly lowered over a period of days to avoid the onset of decompression sickness.
If the rescue team does find a survivor aboard the Bayesian, Dr Watts says their blood will have long since been saturated with nitrogen so a similar process will be necessary.
A life raft possibly from the Bayesian is seen docked at the harbour near the port where the emergency and rescue workers are launching their search operation
This would be a very risky operation requiring expert divers and specialised equipment usually only operated in areas like the North Sea.
But as the case of Mr Okene shows, it is still possible.
The rescue will also be made more challenging due to the extreme depth and likelihood that the cabins are blocked by fallen furniture.
If there are survivors, rescuing them from the ship would require taking a non-diver in a potentially critical state through a technically challenging dive.
Given the depth, rescue divers can only remain aboard the ship for ten minutes at a time without risking their own lives.
Divers return from another dive to the wreckage of the Bayesian. Any rescue attempt will be fraught with danger for the rescuer and survivor and will require specialist equipment
All of this means that rescuing a survivor will be risky for everyone involved but could be attempted if the conditions are right.
Currently, search and rescue teams are operating on the assumption that the missing six are somewhere on the vessel – but hopes are not high.
Vincenzo Zagarola of the Italian Coast Guard said: ‘We think they are still inside the boat, that is our very hard idea.’
‘Our search and rescue activity by sea and air has gone on for around 36 hours. Of course, we do not exclude that they are not inside the boat, but we know the boat sank quickly.’
Asked about the likelihood of them being alive, he replied: ‘Never say never, but reasonably the answer should be not.’
Rescue services (pictured) are working on the assumption that the missing passengers are on the boat. While it is unlikely that any are still alive this is not impossible
Likewise, Dr Watts notes that it would be ‘miraculous’ if an appropriate air pocket had formed where a survivor could get to it.
Matthew Schanck, chairman of the UK’s Maritime Search and Rescue Council, told Business Insider: ‘They’ll assess the structure of the vessel.
‘Are there any air pockets, you know?
‘Is there any noise or any signs of life, and that will factor into their decision-making.
‘But if all the information is pointing towards the fact actually there’s no evidence of air pockets … then it’d be very difficult for them justify divers entering the vessel to go and recover casualties.’
However, at least one of the passengers surviving the sinking of the Bayesian still remains a possibility.
