USS Thresher: The US Navy's Cautionary Tale

this video is brought to you by hellofresh you guys can get 16 free meals and free gifts from hellofresh with the code mega project 16. more about them in a bit [Music] today's mega project is a bit of a cautionary tale on the striving for faster quieter or more deadly equipment which was a hallmark of the cold war between the usa and the soviet union the uss 593 thresher was developed as a direct follow-on and improvement of the skipjack class nuclear fastex submarines that the u.s had developed to help counter the growing fleet of soviet diesel-electric and nuclear ballistic missile submarines were becoming a very real threat to global security the navy realized that their current fast attack subs the skipjack class though innovative in many ways were not up to the task of hunting and detecting the newer submarines that the ussr was producing which could dive deeper and travel faster [Music] the thresher was to be the first real leap forward in many facets of fast attack submarine technology initially she was going to be just an improved version of the skipjack class submarine the skipjacks in their own right represented improvements that changed how submarines were built they were the first to introduce the teardrop shaped hulls which provided a more hydrodynamically efficient shape which resulted in higher underwater speeds and quieter movement through the water however they certainly were without their flaws the first issue was their sail not the big bit of white cloth that you see on old ships the sail on a submarine is that blocky protrusion that sticks out at the top of it and contains the periscope and other stuff like that submarines experience drag and this reduces efficiency and also makes noise which is bad for a whole bunch of reasons the idea of fast attack submarines is to detect their prey without being detected themselves second subs have two types of sonar active which is the one you hear go ping and the passive one which is essentially just very large and sensitive microphones that listen for the slightest sounds allowing them to locate and track their targets it's the latter of those two that are really hampered by the submarine's own noise especially water moving over the aforementioned sail and the noisy forward torpedo room all of which the sub's own passive sonar can detect and it can mask the important noise which is of course the enemy submarine to address these the navy had to reduce the size of the sail they also moved the forward torpedo room to the middle of the sub which allowed for much longer range detection as it reduced the noise pollution that plagued the skipjack class another improvement was mounting all the major machinery and pump installations on rafts suspended from the sides of the pressure hull this eliminated their direct contact with the nullified most vibrations from this equipment that made noise further adding to the boat's stealth capabilities she was also designed with an improved form of hy80 steel which allowed her to dive nearly twice as deep as the skipjack class submarines giving their operational depths of about 400 meters or 1 300 feet over the older skipjack classes 210 meters or 700 feet lastly they introduced what they called seawater piping this was intended to provide superior strength and reduce weight over traditional welding techniques remember this for later it's a bit of foreshadowing all these innovations especially the reduced external drag allowed her to be just as fast as the skipjacks despite having an additional 900 tons of displacement these innovations meant the boat was able to dive deeper than anything the soviets could field at the time the soviets had diesel electric submarines the golf ii class that could dive to 300 meters and the nuclear hotel class which could also dive to 300 meters 90 meters deeper than the skipjack nuclear submarines one of the issues early on in her development was the air pressure system for the ballast tanks the tanks that controlled the buoyancy of the sub this air system could produce pressure up to 4500 psi but the actual manifolds and piping were just off the shelf from earlier submarine classes and could only withstand 3000 psi so they added pressure reduction gear to address this issue they did this to speed up production and reduce costs over having to develop a brand new system docsi testing found that these reducers would become clogged with foreign matter from construction which could have been removed but by adding some cone-shaped filters just before the reducers this alleviated the problem and the air systems functioned fine with dockside and shallow test diving which is to a maximum 400 feet depth with all of this development she was essentially rushed into production and corners were cut in order to just get this new killer sub out to sea as soon as possible many of her air ballast and seawater layouts used older pumps and designs of the previous skipjack class and had far different layouts than previous classes further adding to crew confusion and simulated emergencies consideration was not taken regarding the new much deeper depths that the submarine would operate at which was going to be a crucial factor in a subsequent loss and there's a little bit more foreshadowing now we'll get back to today's video in just a moment but first quick word from our sponsor hellofresh honestly who's got time to cook a full meal from scratch anymore after a long day of work no one really wants to come home and spend hours prepping their food unfortunately other options can be tricky too eating out still a bit risky gave it and all and delivery lots of fees it's not always super healthy well fortunately hellofresh is the perfect solution that checks every box it's going to help you try something that's fresh and adventurous it's affordable it's convenient it's environmentally conscious and it's all from the comfort of your own home with hello fresh you get a specially 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she was lost on april 10 1963 approximately 220 miles east of cape cod massachusetts in 8 400 feet of water she went down while conducting a deep diving test with the loss of 129 crew and civilian shipyard contractors on board the true details will never be fully known but sound recording evidence along with bits of communication from prior to a loss point to a leak that started in the area of the engine room or reactor room it's believed a failed joint or joints started to leak and tons of seawater came in at extremely high pressure and caused a short which resulted in the reactor to scram which is a fancy way of saying shutting down this removed her primary source of power and propulsion leaving her unable to surface so the first inclination of trouble broadcast to the outside world was a message on the underwater telephone that that had a minor problem and honestly any problem when you're that far underwater is not really a minor problem and though they were passing 456 meters or 1500 feet so she was approximately 6818 kilograms that's 15 000 pounds heavier due to a loss of buoyancy at that depth she made several attempts to do an emergency blow which is pumping high pressure air into the sub's ballast tanks forcing out all of the water and greatly increasing buoyancy a post-trek analysis on one of our sister ships found that among all the other factors of the loss that due to the higher pressure 4500 psi to lower 3000 psi pressure difference it would super cool the compressed air which would condense into ice and essentially freeze and distort those cone-shaped filters preventing the effective flow of compressed air to remove the water from the ballast tanks this combined with the loss of her primary driving force from the reactor and the ever-increasing weight of water flooding her rear section kept forcing the submarine deeper then the thresher at approximately 2250 feet that's 900 feet deeper than her rated test depth she imploded and was shredded to pieces over the ocean floor after a long search for the wreckage and several boards of inquiry with over 1 700 pages of testimony and other documents experts were able to reach the following conclusions a contributing factor in addition to the air system filter floors was the new joints that we talked about earlier even though they'd been ultrasonically tested and deemed safe when the sub was built they were never tested again after she was put to sea for the first time in 1961. post analysis of other subs using this form of joining found that there was a much higher rate of failure than predicted and the layout of seawater exposed piping was much more extensive than previous designs other non-design factors i.e human factors were that she'd been assigned a new captain an executive office who had no prior experience with this class of submarine furthermore a normal complement of 13 officers was reduced to 12 as the chief reactor plant officer had to remain on shore due to medical issues additionally four of the newly assigned junior officers had never been to sea before let alone on a submarine about to conduct deep dive tests and so they had no experience with the new layout of systems which were radically different from previous subs in fact the thresher was so new that no shoreway simulators something that all previous classes had have been developed to address all of the thresh's design changes and improvements the bottom line when it comes to the loss of the thresher was that it was a convergence of many factors relating to the design its rush to production procedural administrative and ultimately everyone involved underestimated the environment in which these subs were intended to operate the loss directly led to the subsafe program which was instituted not only to correct design flaws and introduce strict manufacturing construction quality control but also to address procedural items to prevent this from ever happening again in fact subsafe was recommended to nasa by the caib the columbia accident investigation board as the program that nasa should emulate after that shuttle disaster as for thresh's sister subs they were renamed the permit class after the second sub constructed and once all the design flaws were corrected they eventually numbered 13 additional boats that served from the mid-60s until early 1990 when they were eclipsed by the follow-on sturgeon and los angeles-class faster tank submarines so i really hope you found this video interesting if you did please do hit that thumbs up button below don't forget to subscribe and as always thank you for watching [Music] [Music] you

Channel: Megaprojects

Views: 210,447

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Id: tf1_Yor7RZ4

Length: 11min 20sec (680 seconds)

Published: Fri Feb 18 2022