Why did the Titanic tour submarine implode?

Thanks for the answer FallGuy. Anyway, I really enjoyed this thread, because I've also learned so much from everyone here.

 

jehardiman, I was actually thinking more of tourist subs or submersibles like these and these.

I would have thought that the construction costs of these shallow depth vessels would be lower and require less expertise if made from composites, or even simple plastics, than if made from steel, because they could be layed and/or molded somewhat like composite and plastic kayaks and canoes, without need for metalworking equipment. Is that not right?

Those are the ways squirt boats (whitewater kayaks which dive to shallow depths) have been made. Though squirt boating is to some extent an extreme sport, which substantial risks, and has had deaths. (BTW, to the best of my knowledge, the makers of those boats have not been sued or held criminally liable. In fact whitewater boat makers in general rarely get sued, because users generally understand whitewater boating is inherently dangerous. The people here who think the builders of the thread's sub should be sued or held liable maybe don't take the same risk-taking behavior of its passengers into account, the way I see it, though by all accounts they were warned.)

Of course most of the tourist subs emphasize also big windows for better tourist viewing - I don't know if they use glass or plastic windows. (I'm not talking about squirt boats there, in which the paddler's head is exposed to water.)

I don't think most of them fit your definition of submarine or submersible - I suspect some are near-shore land based, rather than requiring an expensive mothership.


As far as narco-subs, I was thinking of full immersion boats like some of these.

Some of them are composite, I assume to avoid easy detection. Specifically, they would have a weaker magnetic field than an inexpensive steel sub would, and they might have a softer sonar echo (I'm not sure of that, and perhaps even a steel sub could be covered by sound-absorbing or deflecting materials). And when at the surface, a composite sub would have a much lower radar cross section than a steel sub. Of course, when immersed, if they are shallow depth vessels, they might still be seen fairly easily from the air. But the aircraft or the sun might need to be close to directly overhead, to be easily seen, much like fish at too large an angle can't be seen.

(I'm guessing that the U.S. Coast Guard doesn't have very sophisticated sub hunting technologies, because of money. Thus a narco-sub doesn't have to be as good at hiding, or go to as high depth, as a full on military sub.)

 

Man, you are just throwing stuff at the wall to see what sticks. Most of what is show in those two links is either older metallic shallow-water vessels in need of complete overhaul, wet open system DPV's (which have their own safety issues), and mostly vaporware based on a semi-functioning prototypes. Some of what are shown are not even submersibles, they are semi-subs or PWC (i.e. the Seabreacher's, which again have their own safety issues). Of all deep submergence systems listed, only two seem actually viable: PISCES- VI (from a long line of successful DSVs); and the Triton Submarines 36000/2 (which is more similar to a bathyscaph than a DSV). For continental shelf work, again only two ready to go; Perry Antipodes (again from a manufacturer with plenty of experience); and the SuperAviator (which is more like two ADS's placed tandem in a fairing). Additionally there are several other older metallic DSVs, most pre-1990, which though proven, would need major investment to bring up to modern standards. Finally, there are the non-metallic 1-atmosphere vehicles. Setting aside the vaporware DeepFlights, this leaves the U-Boat Worx NEMO. This vessel is nothing but an updated Deep Ocean Engineering DEEP ROVER, which itself followed on DSV-5 NEMO and DEEP VIEW. However there is a significant issue with acrylic sphere pressure vessels: they have a limited lifespan , regardless of service. This also applies to vehicles with large viewing domes like the Perry Antipodes or the SuperAviator. The way around this is to use borosilicate glass which is very heavy and can crack is not properly installed.

This is the type of thinking that just got people killed. The design of composites for extreme service requires more engineering and fabrication skill than metals. Anyone who has worked with both will tell you this.

You will find very few people willing to discuss the capabilities of detection, localization, and prosecution of sub-sea targets by any method by any organization.

 

Base jumping is an interesting risk taking adrenalin rush type of thing.

Would a base jumper willingly pay a base jumping service to use a rope with a cut on one spot? How about 5 cuts?

Glaring errors not revealed are not risk taking.

 

jehardiman, I specifically asked about shallow water composite and plastic boats, such as those used to explore sunlit reefs, not deep submersibles or military submarines. I'm asking whether those materials work well for them. I know they apparently work well for squirt boats (though I'm not personally brave enough to try squirt boating - as with cave diving, IMO you have to be a little crazy to go into muddy water hydraulic features with neutral or only slightly positive buoyancy), but I think those are only taken a few meters down at most, which is less deep than the draft of many fiberglass boats, which
obviously do work well. Of course, AFAIK, squirt boating isn't done in reefs - you need the hydraulic for squirt play.

The first link mentions 5 boats, none of which are web subs:

5. The U-boat works Nemo submarine. This link says it has gone into volume production, so it is not vaporware. It is rated to 100 m. The construction material is not listed, but it uses an acrylic bubble window.

4. Seabreacher X. I agree this doesn't really qualify as a sub - or what you call a submersible. It's basically a surface boat that can force itself slightly underwater when moving fast - probably less deep than a squirt boat. As such it would be useless for exploration, because at that speed, you couldn't play tourist in the reef. So I'm not thinking of that boat.

3. Sport Sub Mini Submarine. This link advertises the product, offers training. It says it is fiberglass, and can be delivered in 12 weeks. It is rated to 40 m. There is no info on how many have been sold, or what the window is made of.

2. Ego SE 450. OK, definitely not a sub of any type. Just a boat with underwater windows. You might as well (and more cheaply) use a transparent canoe or kayak, which have been produced and sold in great numbers. I'm not sure you could explore a reef much this way. But you could see some fish.

1. Spymaster mini submarine. This looks very cool to me, if a bit pricey for what they are. I'm a bit puzzled how the head can be in cabin air, while the arms are in the water, without leaking. Maybe the 12m maximum depth helps - in that, it's a bit like a diving or snorkling mask. You could explore some shallow reefs with it. Though with exposed arms, it wouldn't even protect you against aggressive sharks, or other predators, not even against cyano bacteria.

(Though perhaps wet immersion craft that require diving or snorkling gear make more sense, because they can be cheaper. Presumably, you wouldn't need much training or any certification for that. I went on a tourist snorkling trip near Hawaii. We had no training - though we were supervised by people who did. Perhaps the biggest danger was the tiger shark that circled us.)

Anyway, 3 of these are true subs, by most lay people's definitions, in that they go completely underwater - though not by your definitions, which I'm guessing are from the modern military world. My question was, at the depths those are rated to, is there any reason that plastics or composites wouldn't work well?

If you think about it, diving masks are usually plastic (sealed with something like silicone), and are frequently used at greater depths than any of these shallow depth tourist subs are rated for. It is perhaps a little different, because they divers use positive pressure inside the mask, but still. I think snorkle gear doesn't even require positive pressure - just a valve - and it is good enough to explore shallow reefs. And there has been a lot of successful experience using it.

I.E., did the Titan simply take good workable shallow depth technologies and pushed them too far, and without good manufacturing and testing?

BTW, I wasn't talking about detecting military subs. I know that stuff is classified. I'm talking about detecting these brightly colored shallow depth tourist subs. I imagine it would be somewhat like the often published aerial pictures of sharks swimming under surfers and ocean swimmers - which obviously are detected in those pictures, despite their dark color. Of course none of them would be well suited for smuggling - nor should a tourist sub be, for obvious reasons = if it gets into trouble, it may need to be rescued.

 

Again, you seem to misunderstand what what the difference is between an at-pressure (i.e. at ambient pressure ... at the pressure of the immediate surroundings) vehicle and a 1-atmosphere submersible. Of the 5 vehicles listed, only U-Boat Worx NEMO is a 1-atmosphere submersible with a non-metallic pressure hull (which I never said was vaporware, unlike the greater than 100m proposed DeepFlight vehicles; perhaps you need to reread my comments for understanding).

The Sport Sub Mini Submarine and Spymaster mini submarine are at pressure wet subs, or could be more accurately described as open system Diver Propulsion Vehicles (DPVs) and of the worst kind. There is no pressure hull for the operator/s. You see these two vehicles are basically a bucket over the operators head where the operator is kept from drowning, and the vehicle afloat, by the constant bleed of air at pressure greater than the present depth. There is nothing in either vehicle that prevents narcosis, CO2 buildup shallow water blackout, sinkout, or barotrauma. The fact that these two vehicles do not require a personal SCUBA certification or exhaust spent breathing gas directly over the side means that they too occupy a regulatory crack that will not be addressed until there is an actionable casualty (55 people died in diving accidents in the US and Canada in 2018, significantly less than the 633 who died in US boating accidents that same year).

Diver propulsion vehicle - Wikipedia https://en.wikipedia.org/wiki/Diver_propulsion_vehicle
Spymaster mini-submarine: Scuba Scooter fun - boats.com https://uk.boats.com/reviews/spymaster-mini-submarine-scuba-scooter-fun/
https://sportsub.com/faq/

 

Oh! Now I get it. I incorrectly assumed that because there was no breathing apparatus attached to the person's face, that the pressure inside the subs shown was the same as at the surface. And I incorrectly assumed a "wet sub" is one in which your face is surrounded by water.

What I guess you are saying is that the pressure inside these subs is the pressure outside. So, the lack of required scuba training just means that they face the same dangers as a scuba diver, without the trained and practiced knowledge of how to safely handle pressure changes.

Which means that if wet subs become common enough, there will be a lot of deaths, just as there have been a fair number of deaths of people who go to a department store, buy a cheap "kayak", and go out by themselves on the water, without proper clothing, gear, knowledge, training, or experienced companions. And wet subs could become common, because of the relatively cheap models that are becoming available, and because there are plans for building your own, on the web - very much like what has happened with kayaks, and was perhaps always true of canoes and rented motorboats. (Whitewater kayaking is a little bit different - it is obvious to almost everyone that there is significant danger involved.) All that has to happen to create the casualties you anticipate is for Costco or Dick's sporting goods to offer a cheap model, as they do for kayaks.

When I went on the tourist snorkling trip, they kept us within 10-15 feet of the surface. So maybe the dangers associated with pressure change weren't all that great - perhaps marginally worse than diving into a swimming pool near the diving board, and swimming to the bottom, and maybe less than cliff diving. And perhaps the seal around the mask compresses a little, so the pressure inside the lungs is slightly greater than 1 atmosphere.

After doing a little reading, I am now glad I gave up on the idea of learning to dive, because the free intro session a local swimming pool offered didn't happen to provide equipment that fit my face well. I sometimes have had trouble equalizing my ear pressure in aircraft, and it simply didn't occur to me that ear pressure equalization would be needed diving - or even snorkling at greater depths than those in that tourist trip. Though now that I know that I have the type of ears that need to be periodically professionally cleaned of wax to stay clear, maybe I could revisit that - with training.

 

Perhaps, perhaps not. There is a reason that these type of "vehicles" are only deployed at very shallow depths. Just like there was a reason that the standard original steel SCUBA tank was 72 cft volume, it physically limits risk. It would be almost impossible to "bend" anyone with what is provided. At 1 bar (i.e. 33 FSW) the minimum time to bend anyone is ~360 minutes. Normal tidal respiratory volume is ~0.5 to ~1.0 cfm (depending or exertion level). Unless modified, these "vehicles" don't have enough air to put anyone on the decompression tables. If you bail out of a Spymaster mini submarine at 33 FSW, you already have TWO (2) full breaths of air in your lungs. which makes it fairly easy to surface IF you don't panic. While I personally don't like these things because of my training, that doesn't mean that they haven't been subjected to a significant amount of psychological and/or physiological engineering.

 

One year on....

Another billionaire wants to ride a submarine to the Titanic wreckage https://www.yahoo.com/news/another-billionaire-wants-ride-submarine-192743622.html

 

@jehardiman you mentioned earlier in this discussion that some organic plastics compress to (from memory) ~20% of sea level size at extreme depths.

I'm left wondering how carbon fibre reinforced epoxy composites fare with this. Any idea?

If significant compression occurs then it would be extremely difficult to maintain the integrity of the seal between the composite tube and the domed metal caps.

 

Depends on the matrix and lay-up. Vacuum bagged cold-moulded epoxy and woven s-glass fairings on the DSV's moved very little (as long as you sealed every cut surface...). Basically, the "plastic" matrix only fills the voids between the fibers, supported fiber on fiber gives compressive dimensional stability. So matrix to fiber ratios become important (e.g. the TITAN winding video).

Depending on the design, bulk compression is one of those things that can work for you or against you. In the TITAN design, the actual caps were separate from the end rings. This puts shear across the bolting face, not the ring to cylinder glue joint which should be longitudinally in compression and radial loading depends on the tube stiffness (i.e. depending on L, D, and t of the carbon fiber tube you could have either radial tension or compression in the glue joint.)

 

Many thanks, the winding video was of concern to everyone I think; and it appeared matrix to fibre ratios were given as little consideration as void control.

 

The joint between the heads and the shell would not be the issue. A simple mechanical anchor would be fine if properly designed. The vessel should have been tested to failure and then a conservative safety factor applied. But then again, what would it matter, if I remember right, it had been down what, 15 - 20 times?

 

Would you think it reasonable to expect the customers for this kind of sightseeing expedition to have much understanding of the process of number of cycles to failure?While it remains (for now) a business outside the forces of regulation and without any need to demonstrate any level of safety other than "it came back last time",that may gradually change in the light of the events under consideration.We have the parallel of civil aviation where the passengers assume a level of regulation and the non-flying public can consider it unlikely that they will be struck by falling debris since inspection is mandated for the structure at stipulated intervals.It increases operating costs a bit but the safety record is exceptionally good.

 

Final USCG Report is released.

https://media.defense.gov/2025/Aug/.../SUBMERSIBLE TITAN MBI REPORT (04AUG2025).PDF