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It has been reported that a civilian submersible touring the wreckage of the Titanic has gone missing in the North Atlantic, and a search and rescue operation is underway.
Comments sent out 23/06/2023 after reports that debris found in the search site is from the missing Titan sub:
Dr Jasper Graham-Jones, Associate Professor in Mechanical & Marine Engineering at Plymouth University, said
“It is very sad that these crew and adventurers have lost their lives. The US coastguard detailed the wreckage was found 1600ft from Titanic’s bow in five pieces. These include critical forward and rear sections of the subs pressure bulkhead.. Normally , such craft pressures’ bulkhead are round like a ball as it provides strongest shape. To increase passenger numbers the Composite craft was extended. This increase loads in mid sections above normally seen in the rounded end. Imagine an eggshell, that can withstand high loads but is very brittle if bent. Extending the cabin pressure longitudinal bulkhead puts increased fatigue and delamination loads. Fatigue is where you can bend a wire backward and forward and then break under lower load. Delamination is like splitting wood down the grain of a log, easier to do than chopping across the grain. The debris field of multiple small parts show the catastrophic and rapid failure of the sub which has imploded extremely quickly.
“This craft has lasted 25 runs down to Titanic and back to the surface. Each return run would put cracks in the pressure bulkheads. This might be small and undetectable to start but soon become critical and produce rapid and uncontrollable growth. The loading and critical crack size is basic standard engineering taught to all Engineering students.
“Composite structures, like carbon fibre, or glass fibre are very good in reducing these fatigue cracks. It is this reason why most modern airplane wings and helicopter blades are made of composite structures.
“Has there been regular non-destructive testing and evaluations of any surface or subsurface cracks? Was that done by an independent qualified staff?
“Engineering is complex, and not everyone can know everything. We need to check our calculations, assumptions, and implement engineering best practice. Throughout all industries Class association are there to give this very helpful technical information. From Wikipedia “A ship classification society or ship classification organisation is a non-governmental organization that establishes and maintains technical standards for the construction and operation of ships and offshore structures. Classification societies certify that the construction of a vessel comply with relevant standards and carry out regular surveys in service to ensure continuing compliance with the standards.”
“In July 2022, Dr Dawn Wright and Caladan Oceanic completed a scientific expedition to Challenger Deep at southern end of Mariana Trench – the deepest place on Earth, using a crewed deep-submergence vehicle called Limiting Factor. This was commercially certified by Det Norske Veritas Norway (DNV) for dives to full ocean depth, and is operated by a pilot, with facilities for an observer.
“Currently, more than 50 organizations describe their activities as including marine classification. Why did Oceangate submersible not do the same as every other deep-sea craft and use the services of Marine classification to confirm it was safe for paying passengers? In international water, where Titanic sank, there are no rules that require such regulations. If, as an individual, you want to put yourself down in unsuitable craft, that is your risk. However, this should be very different when it comes to paying passengers, and no legal waivers that you might sign can remove legal responsibility and duty of care.”
“I hope the design is fully examined by various Classification organizations so that lessons can be learnt, and freely published. Carbon Composites are excellent materials but have limited life when subject to excessive loads or poor design which leads to stress concentrations. These stress concentrations mean a normal functioning parts failure sooner and under lower loads then previously seen. This could be measured but required experts in non-destructive testing (NDT) of Composites. In the same manner used by Aircraft and helicopter manufacturers.
“Failure investigations start by collecting all available parts. This I have done on many occasions. Critical making sure you try and collect carefully so that no further damage is caused to collected parts. Also, a log of parts and locations from largest to smallest. These locations will spread from surface through the water column to sea floor. From visual and magnified views, components’ crack paths can be recorded. Typically, a map of all these crack paths this can be fixed to a few initial locations. From these initial locations possible failure causes can be suggested.
“This might require scanning electron microscopes and Xray detection, to analyse material compositions and crack growth rates and directions. This is likely to take 6 months+ as there are many interested in the results both personally and for legal redress.”
Prof Roderick A Smith, FREng, Imperial College London, said
“It looks likely that the issue is a failure of the pressure hull. As much debris as possible needs to be brought to the surface for close examination. The site of the rupture needs to be identified
The body consists of a carbon fibre cylinder end capped by titanium hemispheres . Carbon fibre fails by delamination or from internal defects in its construction .The joints between the carbon fibre and the titanium need very careful inspection. It is also possible that the bolted down sealing device which lowed entry has failed. The violence of the implosion means that it may be very difficult to determine the sequence of events. Hence the need for retrieval and painstaking examination if possible”
Dr Jasper Graham-Jones, Associate Professor in Mechanical & Marine Engineering at Plymouth University, said
“Critical are the composite hull. The rear cover and landing frame could separate from the Carbon fibre hull. If the debris include past of the Carbon fibre hull this this is likely to be a implosion failure, that could have been by delamination fatigue failure”
Comment sent out 22/06/2023 discussing the oxygen levels in the submersible:
Prof Hugh Montgomery, Director, UCL Institute Human Health and Performance, University College London (UCL), said:
How will the crew on the Titan be affected as the oxygen runs low? Would breathing exercises or meditation for example extend the air supply time? How would the temperature of the cabin affect the crew?
“In short: humans are obligate aerobes- that is, they must burn fuel with oxygen, and can only support a small amount by non-oxygen burning for short periods.
“The body makes every effort to defend a core body temperature (about 37C), so allowing the chamber to cool won’t reduce oxygen demands: indeed, shivering may increase it.
“The only effective way to limit O2 demand in this circumstance is not to burn excess energy- so stay immobile/ sleep as much as possible. Meditation can slightly reduce demand (less ‘stress hormones’ and less movement/ more relaxed muscles) but a) such effects will be marginal b) they need to be practiced and c) the whole crew would need to have been practiced in this way.”
Comments sent out 21/06/2023 after reports that ‘underwater noises’ were detected:
Dr Jamie Pringle, Reader in Forensic Geosciences, Keele University, said:
“The fact the acoustic noises are 30 mins apart is a great sign, unlikely then to be from another submarine (which typically only go down to 900m), a surface ship propellor which would be continuous etc so most likely manmade. Acoustic (sound) noise travels far in water (a la whale sounds) so that is both good and bad news, you would still need 3 of those static buoys to be able to triangulate the sound source to get a position fix (as they do to calculate earthquake epicenters etc). These sonobuoys used are using either passive or active detection (the BBC have done a great job of explaining this, see – A visual guide to the Titanic sub rescue mission – BBC News).
“This is different from a sonar survey, which uses either a towfish from a surface vessel or Unmanned self-propelled one for deeper waters (this was what was used to find Emiliano Sala’s crashed aircraft in the English channel a few years ago for example) but this was a lot easier to locate as a) the water was so much shallower and b) wasnt lots of Titanic ship parts left in a debris field which would make it hard to spot the sub from the rest. Good science bit behind this is here – Emiliano Sala search: Body seen in plane wreckage – BBC News”
“I should also add a caveat that the sound could, of course, be coming from something other than the sub, let’s not give people false hope here, the lack of oxygen is key now – even if they find it, still need to get to the surface and unbolt it”
Dr Rob Larter, Marine Geophysicist, British Antarctic Survey, said:
What might these bangings might be?
“There are a lot of anthropogeneic and natural sources of noise in the ocean (shipping, small earthquakes, fracturing icebergs etc.). More detailed information would be needed on the frequency range, repeat interval, source location etc. to answer this question.”
How are these bangings detected? Using what equipment?
“Hydrophones or transducers that convert acoustic signals to electronic ones, which can then be analysed using signal processing software.”
Can they know for sure they are coming from the submersible?
“Using an array of hydrophones or transducers the phase of an acoustic signal arriving at the array can be analysed to determine the direction it is coming from. By observing at different surface points the source location can be determined by triangulation. If the source is not right at the sea floor a “ghost” arrival reflected from the sea floor may also be detected that will show how high above it the source is located.”
Comments sent out 21/06/2023:
Professor David Andrews, Professor of Engineering Design (UCL Mechanical Engineering), said:
“The first task is to find the craft, which would be no mean feat. Even on the surface, which would be the best chance of a successful rescue, it will still be difficult to find because the craft is so small and low in the water. If the vessel is on the bottom of the ocean, finding it will be even harder. It took Ballard a very long time to find the relatively enormous Titanic.
“The fact is that people rarely travel to these depths, which are many times deeper than those at which military submarines can operate. There are lots of unknowns. It’s a very novel expedition and we don’t have a lot of information about the craft.”
Professor Alistair Greig, Marine Engineer (UCL Mechanical Engineering), said:
“If the submersible is on the seabed, there are oceanographic research vessels that can go that deep and have manipulator arms that could attach a line to the stricken submersible. Woods Hole Oceanographic research centre have Alvin, for example. But it depends on where these vessels are and how ready they are to deploy. They have to be transported to the site, dive, find the stricken submersible, attach a line or something similar, and bring it to the surface. Each step takes time and the clock is ticking.”
Comment sent out 20/06/2023:
Dr Nicolai Roterman, deep-sea ecologist and lecturer in marine biology at the University of Portsmouth, said:
“The prognosis is not good in my opinion, but the most likely scenario is that there has been a communication or power failure. With a research deep-sea submersible, there would be fail-safe systems to allow the jettisoning of weight even without power or with a research power system, but it’s not clear what fail-safe systems this commercial submersible has. If Titan has successfully jettisoned weight, then it should float to the surface. Typically, the hatch on a deep-sea submersible can be opened from the inside, but it appears this may not be the case for Titan, where the hatch is bolted on from the outside. As a consequence, even if they are floating at the surface, the occupants of the submersible will still have to rely on the oxygen reserves, giving them a total of 3-4 days at the most.
“If the submersible is intact but unable to jettison weight or is snagged on the sea floor, the challenges for rescue become more acute, even if Titan is found. There are no submersibles that I’m aware of capable of rescuing people from a submersible at the depth of the Titanic (3,800 m). However, it could conceivably be possible for a remotely operated vehicle (ROV) to help un-snag the Titan, or to attach a tether of some sort. Whether or not retrieving a submersible from 3,800 m depth is practical is another matter, given the roughly 10-tonne displacement of Titan and the kilometres of heavy cable required, a very powerful winch would be needed. The submersible Pisces III was retrieved from a depth of almost 500 m in 1973, but Titan is also 8-times deeper and I’m unaware of any submersible retrieval from such depths.
“If there was any kind of hull breach, the occupants would succumb to the ocean in a near instant, given the more than 5500 pounds per square inch (PSI) pressure exerted by the ocean at the depth of 3,800 m, which is 380 times the air pressure at the surface. Another equally unpleasant possibility is fire. The air in deep-sea submersibles can be enriched in oxygen, which could increase the risk and intensity of fire. Often petroleum-based makeup and skin creams are prohibited in deep-sea dives owing to the fire risk. Even without oxygen enrichment, any fire would incapacitate the occupants quickly in such a confined space.
“I think it is important to remember that to us humans, the deep sea is a very inhospitable place. Even the most reliable technology can fail, and therefore accidents will happen. With the growth in deep-sea tourism, we must expect more incidents like this.
“Deep-sea tourism is not without impacts on the environment and, rather like the tragedies and human detritus left on Mt. Everest, a conversation is warranted about whether this is a worthwhile human endeavour going forward.”
Comments sent out 19/06/2023:
Prof Alistair Greig, Professor of Marine Engineering, University College London, said:
“I know nothing specific about the vessel in question, but going by pictures in the media, I can make some broader observations based on my experience with submarines.
“Submersibles like this usually have a drop weight, which is a mass they can release in the case of an emergency to bring them up to the surface using buoyancy. If there was a power failure and/or communication failure, this might have happened, and the submersible would then be bobbing about on the surface waiting to be found. Submarines are not designed to be on the surface, so it would be mighty uncomfortable for the occupants.
“Another scenario is the pressure hull was compromised – a leak. Then the prognosis is not good.
“If it has gone down to the seabed and can’t get back up under its own power, options are very limited. While the submersible might still be intact, if it is beyond the continental shelf (depths more than 200m) there are very few vessels that can get that deep, and certainly not divers.
“The vehicles designed for Navy submarine rescue certainly can’t get down to anywhere near the depth of the Titanic, and even if they could, I very much doubt that they could attach to the hatch of the tourist submersible.”
Dr Jamie Pringle, Reader in Forensic Geosciences, Keele University, said:
“Aquatic search is pretty tricky, as the ocean floor is a lot more rugged than on land, and water isn’t homogenous either – there are different stratified levels, currents, etc.
“A typical land search for a missing person or vehicle would move outwards radially from the last known position (as described here). This is how this search is also likely being conducted, albeit in water (see here) and incorporating information on the water-specific variables cited above.
“Techniques vary, but in that water depth, a sonar search system would need to be specialised to a very narrow beam but high enough frequency in order to resolve a small submersible. The search for Emiliano Sala’s plane a few years ago, a similar-sized object, took less than three days, but was in a lot shallower water depths (although it did have similar current and also tide factors to think of).
“The MH370 downed plane, lost in 2014, had a very large search radius and still hasn’t been solved (despite the black box that should have been pinging – see here). This search should be a much smaller search radius, as the submersible was reportedly on a relatively simple down and up dive.”
e.g. https://www.bbc.co.uk/news/world-us-canada-65953872
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