If you thought that space travel was the “next frontier” of human discovery, you may not have considered deep-sea exploration. While 12 people in the world have been to the surface of the moon, only three have spent time at the deepest part of our oceans. Much of this has to do with the immense pressure at the bottom of the sea, as well as its frigid temperatures and total darkness.


Still, there are several companies who have braved the unknown including Triton Submarines who have managed to engineer a sub that can reach the deepest spot in the ocean. Then, there is the now infamous OceanGate Expeditions whose ill-fated dive this summer ended in a “catastrophic implosion.” What went wrong with OceanGate? And more importantly, what has to go right to make a submersible that can withstand deep-sea pressure?


The OceanGate Tragedy


A little over a month ago news outlets announced that the Titan, a submersible made by OceanGate inc., was missing en route to explore the Titanic wreckage. At the time, the vessel reportedly only had at most 48 hours of oxygen left. For the next few days, the world watched with horror as the minutes and hours dwindled on macabre countdown clocks all over the internet.

On board the doomed vessel were 5 men: Paul-Henri Nargeolet, a French deep sea explorer and Titanic expert; Hamish Harding, a British businessman and aviator; Shahzada Dawood, a Pakistani-British businessman; his 19 year old son Suleman Dawood; and Stockton Rush, the CEO of OceanGate himself

As soon as authorities reported the sub missing, a massive search operation went underway. The U.S. and Canadian Air Forces and Coast Guards led the search along with aircrafts from both countries’ air forces. Other commercial and research vessels from around the world joined the effort by providing ROV’s (remotely operated vehicles) and other deep sea tech. About a week later the U.S. Coast guard announced that crews had found a debris field near the titanic wreckage. The Titan had suffered a “catastrophic implosion,” with no chance of survival for all 5 passengers.




Are All Submersibles Inherently Dangerous?


In the fog of such a terrifying and tragic event, it almost seemed like the Titan’s demise was a casualty of cutting edge technology braving the unknown. But soon, a twitterstorm resurfaced videos of Stockton Rush touting experimental and frankly alarming DIY features of his vessel including the use of a bluetooth Playstation 3 controller and an “elevator button” to turn on and maneuver the sub. 


And it turns out, the Titan is certainly not the first submersible to carry out such a dive. Around the world there are a few other vessels capable of reaching the depths of the Titanic- some 12,500 feet below the surface.


One submersible, the DSV Limiting Factor, has gone much further. The vessel belongs to Florida based company, Triton Submarines. Triton’s subs have reached the so-called “Challenger Deep” within the Mariana Trench. The Challenger Deep is the deepest area of any ocean in the world with a staggering depth of 35,768–35,856 ft. 


But not only that, The DSV Limiting factor has completed a mission known as the “Five Deeps Expedition,” where the sub became “the first manned descent to the bottom of each of the world’s five oceans.” So it’s safe to say that the DSV Limiting Factor has lived through a few deep dives.


So, it begs the question: how could passengers on the DSV Limiting Factor go down some 35,000 feet multiple times and return to tell the tale, but the Titan imploded at less than ⅓ of that depth?  




High Pressure in the Depths of the Ocean



One of the biggest challenges to deep sea exploration is the extreme pressure. As you descend into the ocean, water pushes down on you. The further down you travel, the greater the amount of water and therefore pressure is placed on your vessel. In fact, every 10 meters (around 33 feet) you travel down, 14.25 lbs of additional pressure is exerted on your vessel at every square inch of its surface. Because the Titanic is 12,400 feet down, the pressure exerted on a vessel would be 5,500 lbs on every square inch of its surface. Pressure in the Mariana Trench can reach 15,500 PSI. Obviously, in order to be able to withstand such pressure, you would need to design a submersible with incredibly strong materials and perfect engineering. 




Triton Submarines: Engineering a Sub that can Withstand Extreme Pressure



In April of 2019, private equity investor, explorer, and former naval officer Victor Vescovo “achieved the deepest dive made by any human in history” in the Challenger Deep. Vescovo made the dive in Triton’s DSV Limiting factor, and reached an incredible depth of 35,843 feet.
Designed in collaboration with Triton Submarines, Vescovo, and a host of engineers and scientists, the Limiting Factor is a feat of submersible engineering. In fact, it is the first and only manned-submersible certified to reach full ocean depth.  
Much of the Limiting Factor’s success is probably due to the shape of its body and the engineering of it’s hull. The sub measures 15 feet long, 9.2 feet wide, and 12.2 feet tall and resembles a high-tech suitcase or trunk.



The Hull



The Limiting Factor can fit a maximum of two people inside its spherical shaped hull. Divers climb through a top hatch to enter the hull which has two comfortable looking leather seats; a joystick and panels of high tech controls; several touchscreens; and 3 viewports to gaze out at the bottom of the sea
Most importantly though, engineers constructed the hull out of 90mm thick titanium. And unlike other titanium hulls, the Limiting Factor’s engineers chose not to use welding to attach the two hemispheres. Instead, the team opted to use a  “combination of bolts and precisely machined contact surfaces.They did this to add another layer of security to the sub because the team worried that welding might cause changes in the metal that could become dangerous under extreme pressure. In Fact, The hull is so perfectly engineered that it is “machined to within 99.933% of true spherical form.” 



Other Safety & Tech




  • Communications– Engineers equipped Triton Submarines Limiting Factor with an Underwater Telephone system (UWT) that uses acoustic transmission to communicate with the team above the water. This way, the Pressure Drop can maintain constant contact with the Limiting Factor. 


  • Complete Visual Awareness- In addition to three viewports, the sub is equipped with low-light cameras that offer a 360 view of the passenger’s surroundings. This greatly aids the pilot who has the vital job of navigating the sub in the darkest depths of the Hadal zone (the deepest zone in our oceans).  


  • Sonar and Ocean floor Mapping– Mounted on the bottom of the hull is the so-called “Kongsberg EM124 multi beam echo sounder,”  a sonar device that uses echoes to completely and accurately map the ocean floor. This not only allows aids in planning future dives, it can also map uncharted areas or fix mistakes of previously mapped areas in the deep sea. This could help us with our deep sea mapping and may potentially “lead to the reclassification of some” recorded depths.


For more on Limiting Factor’s safety features click here.



Why the Titan Failed



Obviously, creating a submersible vessel that has the ability to dive to such depths takes time, money and resources. Was the Titan’s catastrophic implosion just a fluke? Or was it a preventable tragedy? Many experts in the submarine/submersible community seem to think the latter. 


The Titan lost communication with its mothership when the sub was reportedly around 11,500 feet down. While nowhere close to the Mariana Trench, the immense pressure at that depth is akin to the weight of the Eiffel Tower. While the investigation into what caused the Titan to implode is still ongoing, we have seen many experts take some educated guesses.




The Hull



Perhaps the most likely reason the Titan failed was because of its experimental hull. Unlike Triton Submarine’s Limiting Factor and most other submersibles, the Titan’s hull was not made of titanium or steel. Instead, OceanGate opted to use carbon fiber composite, a material that has never been used in deep-sea exploration. This is because “The ability of carbon fibers to withstand repeated cycles of stress, especially compressive stress, under deep-sea pressures is not well understood, making it difficult to design safe hulls based on carbon fibers.”


Essentially, Carbon fiber, unlike titanium or steel, will break down slowly under repeated pressure. I.E. repeated deep-sea dives: Unlike homogenous, isotropic material, such as the titanium… carbon fiber hull suffers with each dive. The fibers can crack, bend, lose adhesion with the epoxy matrix… and other problems that are peculiar to composites.” Given that the Titan had reportedly traveled to the Titanic at least 10 times, it seems likely that the hull had begun to break down over time.  




The Shape of the Vessel



The reason that OceanGate and CEO/Co-founder Stockton Rush probably wanted to use carbon fiber is because of its light-weight, yet strong properties. Rather than being spherical in shape like other submersibles, OceanGate designed their hull to be cylindrical, probably to be able to fit more high-paying customers. However, the shape required more material and became heavier, leaving OceanGate to try to lighten the load- hence the idea to use carbon fiber.


Carbon fiber is used in engineering for many purposes, including on aircrafts. The material is often used in airplane fuselages, like in the Boeing 787 Dreamliner. The main difference between airplanes and subs however, is that airplanes are subject to internal pressure, while submersibles are subject to external pressure. The material is great at resisting expansion, not so great at compression. Additionally, the hull’s cylindrical shape could have contributed to its implosion. According to experts, spherical shapes are much safer than cylindrical when it comes to submersible hulls because water pressure can apply equally to the vessel’s surface.” 




Lack of Certification



But how could such a major design flaw go unnoticed by the submarine industry? The answer is, it wasn’t. Unlike The Limiting Factor, the Titan was not certified by any third party (like the DNV). In fact, “Of roughly 10 submersibles that exist in the world and are capable of diving to the depth of the Titanic – nearly 4,000 meters below the surface – only OceanGate’s Titan was uncertified,”
This means that while other submersible companies (like Triton Submarines) went through rigorous testing and certification through a third party, the Titan only got in-house testing. In fact, even OceanGate’s own employee, David Lochridge, who the company hired to inspect the sub, found major flaws. Among other problems, Lochridge found that the hull had “very visible signs of delamination and porosity” and recommended a full scan of the hull before diving again. Lochridge later alleged he that OceanGate fired for raising these safety concerns.




Repeated Warnings



Perhaps even more shockingly, many industry experts had warned Rush that his vessel could result in a tragedy. In fact, according to Forbes, a group of industry professionals wrote Rush a letter in 2018 expressing their concerns about the Titan. It is unclear whether Rush read or responded to it. Other individuals in the submersible community echoed these concerns.
In a series of emails, deep sea specialist Rob Mccallum warned Rush multiple times that “you are potentially placing yourself and your clients in a dangerous dynamic.” And that “Until a sub is classed, tested and proven it should not be used for commercial deep dive operations.” To which Rush replied, “We have heard the baseless cries of ‘you are going to kill someone’ way too often. I take this as a serious personal insult.” 
Even those who had been on the vessel with Rush voiced their concerns. Karl Stanley, a submarine tourism and submersible expert took a dive in the Titan in 2019. Throughout the dive, Stanley described hearing alarming cracking noises and worried about the structural integrity of the hull. Afterwards he urged Rush to re-evaluate the hull before future dives. After the tragedy Stanley said “He definitely knew it was going to end like this. He literally and figuratively went out with the biggest bang in human history that you can go out with,” 







Sadly, we can only speculate whether Rush knew his vessel was unsafe or if he was blinded by ambition. Poignantly, Titanic movie director, deep-sea explorer, and partial owner of Triton, James Cameron said “I’m struck by the similarity of the Titanic disaster itself, where the captain was repeatedly warned about ice ahead of his ship, and yet, he steamed up full speed into an ice field on a moonless night, and many people died as a result,” per NPR.
Despite the tragedy of the Titan, there are many deep-sea experts and some submersible companies like Triton Submarines who do care about safety. In their safety guide Triton says: “Triton Submarines does not produce experimental vehicles, but series-built submersibles that are compliant and delivered with full certification by a third-party classification society.”  Innovation and hard work from companies like Triton Submarines will allow us to explore unknown depths and discover new deep-sea creatures
Still, it’s safe to say that many will think twice before ever stepping foot in a deep-sea submersible. And even if you did want to take the dive, you will probably have a hard time finding a submersible company that will take you down more than 1,500 feet. And it’s probably for the best. Perhaps for now, we should leave dives in the deep-end to experts and explorers rather than tourists.








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