Titanium and carbon are meant for each other. Nothing innovative there unless we’re taking about the 1950s

Apparently if you put titanium and carbon fibre next to each other in salt water the titanium begans to corrode at quicker rate.

Can read more here: https://www.corrosionpedia.com/galvanic-corrosion-of-metals-...

> Therefore, there is no significant gap between titanium and carbon-fiber-reinforced composite to create galvanic corrosion. This means that commercially pure titanium and its alloys are completely resistant to galvanic corrosion when they are coupled with carbon composites.

Small things, e.g. insognificanz rebellions, ah, gaps, do add up.

I see a problem in stress loads so. Titanium and carbon fibre composites behave differently under load. And at those depths, they are under a lot of load. These small differences induce additional stress at the critical joint between bulk heads and submarine body. That stress causes, over time, material fatigue.

That's why those components are, in most othee use cases, fatigue tested to their breaking point. Knowing that point, allows you to define a save service life for those components and replace thek way before they fail.

The article you cite says "Therefore, there is no significant gap between titanium and carbon-fiber-reinforced composite to create galvanic corrosion. This means that commercially pure titanium and its alloys are completely resistant to galvanic corrosion when they are coupled with carbon composites." This seems to be the opposite of what you are asserting.

Serotta did too when making this bike: https://www.bigshark.com/articles/serotta-road-bikes-pg318.h...

There is a rather large difference between a road bike and a vessel that needs to withstand the pressures of being 4000 meters underneath the ocean.

Bicycles are not submersibles.

They can be, but it’s a one way trip.

Danny MacAskill begs to differ.

https://youtu.be/K_7k3fnxPq0

James Cameron is extremely critical of the design of the sub, and of Rush's attitude [0]. He says that carbon fiber was a very poor choice and that it had been known for a very long time, and that "deep submerged diving is a mature art".

If you think you're going to reinvent the wheel and bypass regulatory bodies and ignore subject experts, and move fast and break things, you're delusional.

Any baby can break things; any toddler can break rules. What's hard is to discover new rules, make things that don't break.

[0] https://www.youtube.com/watch?v=rThZLhNF_xg

Exactly. What really gets me is that he would subject passengers - one of which is a teenager - to this kind of risk. It really gets me, that kid probably had absolutely no clue about the real level of risk involved.

Carbon is fantastic stuff if used properly, used improperly it will seem to be perfect right up to the point where it fails catastrophically.

A few weeks ago there was a tragic caving accident at a local school here where a boy drowned when the outdoor adventure group entered the caves even as flood waters were rising from a storm.

I told my 10 year old son that one day his life might depend on being able to recognise danger and not follow the herd. I said that might mean you staying out of the cave even if the teacher and all the other students went in, called you names, etc.

He rightly pointed out that would be almost impossible such is the power of peer pressure. Still I hope if that day comes he remembers it.

You are right and your son is also right. As a father of sons I share your concerns and I hope that I'm able to give them the capability to withstand that peer pressure. I've been - and still am - subject to this on account of not drinking alcohol, smoking or using drugs. To the point that it becomes ridiculous ('don't be boring'). This has been a recurring thing since my teenage years and I really don't get why people feel the need to pressure others into joining them in their stupidity. Just like I don't push them to behave like I do.

But it's been tough, on occasion and I can see the point that your son makes, and I hope with you that if that day comes that he will remember it. FWIW you can tell him this internet stranger agrees with his dad and that peer pressure can be overcome.

> A few weeks ago there was a tragic caving accident at a local school here where a boy drowned when the outdoor adventure group entered the caves even as flood waters were rising from a storm.

That's awful, and if there's one thing that I learned from Thai cave rescue a few years ago (https://en.wikipedia.org/wiki/Tham_Luang_cave_rescue) it's that you never want to go swimming in caves when it might start raining.

I write about the propensity of adolescents worldwide to take unreasonable risks in here:

https://albertcory50.substack.com/p/how-about-not-overcoming...

it isn't just Americans or even First Worlders. In some cultures they're not able to do it, but they all want to. And it's -- guess what? -- peer pressure that makes them do it. Brain scans show that they recognize the danger as well as adults do, but they're more susceptible to the peer pressure.

It's ok to be afraid. No one had to go down to 12,500 feet to see the Titanic.

A father at least got it, flat out refusing to send his son on that trip, he survived.

https://i.stuff.co.nz/national/132006337/dad-who-stopped-son...

Yep, a helicopter pilot used to doing real risk assessments.

Resisting peer pressure is a life long skill, eventually it just merges with one’s sense of ethics and duty.

Are you in Whangarei? The incident at the Abbey caves was really so tragic and preventable. I still don't get what went through the teachers heads, it's to rainy to go rock climbing, so we go caving instead?!

Yep, I hope some solid information about their risk assessment process comes out.

The kid's father seems to bear a lot of responsibility in his son's demise.

> In the days before the Titan vessel went into the ocean off the coast of Newfoundland, Canada, the 19-year-old university student accompanying his father on the expedition expressed hesitation about going, his aunt said Thursday in an interview.

> Azmeh Dawood — the older sister of Pakistani businessman Shahzada Dawood — told NBC News that her nephew, Suleman, informed a relative that he "wasn't very up for it" and felt "terrified" about the trip to explore the wreckage of the Titanic.

> But the 19-year-old ended up going aboard OceanGate's 22-foot submersible because the trip fell over Father's Day weekend and he was eager to please his dad, who was passionate about the lore of the Titanic, according to Azmeh.

https://www.nbcnews.com/news/world/titanic-submersible-shahw...

Ugh, that's so sad. Dying to please your old man. He seems to have had the best intuition about the safety risks involved then.

That or he still thought it was safe but was scared regardless.

Even though everyone knows flying commercially is incredibly safe, lots of people are still anxious about it. Its not like this kid, or maybe any of the other customers, knew of any of the safety concerns and just thought it was as safe as flying.

Flying commercial is safe.

Its also good to remember the titanium wings bear the full weight of the plane.

50% of the wings on a 787 are carbon fiber. Which was tested far above loads before failing.

When corners aren't cut building the planes, and Boeing has never cut corn... oh, crud.

Almost the full weight. The fuselage typically contributes in the neighborhood of 10% of the lift.

Sad, maybe. Seems like one of the best ways to go. Respect.

I doubt it felt like a good way to go to someone who was scared to go on the thing in the first place. Maybe it went from no indications of a problem to near instantaneous implosion in a moment, but I kind of doubt it. I’m guessing that carbon fiber was anything but silent as it approached the moment of catastrophic failure. I’d like to think they didn’t know what was about to happen, but it seems unlikely.

This was one of the reasons I always hoped their deaths were as quick as could be. As a parent myself, the idea of looking my child in the eyes for days on end, knowing that I’d condemned them to death with my own hubris… I can’t imagine anything more miserable.

> Carbon is fantastic stuff if used properly, used improperly it will seem to be perfect right up to the point where it fails catastrophically.

It blows my mind that anyone thought it was a good idea to make a deep-sea submersible out of the stuff.

Carbon's tendency to abruptly fail without warning was a source of significant anxiety whenever I'd go riding the more aggressive trails on my ibis mojo hd3. And that wasn't a certain death outcome should the carbon let go...

Also people have been making bikes out of carbon for a while and reputable brands know what they're doing.

And even then. If you buy a carbon bike second hand (which I would advise against) you'll have to do an absolutely minute inspection to ensure there are no cracks, especially the front fork and all the places where there are inserts are excellent spots for hairline cracks to develop.

I suppose it is easier to move fast and break things when all you need to do is post pictures of cats, but diving to 4km depth you only get to break once I’m afraid

How costly was Cameron venture ? it seems so strange to see a crew die in conditions that were already mastered, with near no added benefits.

Cameron says the sub had sensors that would detect if the sub was starting to delaminate. He says the sub was trying to return because they probably had a warning. How terrifying.

I'm curious about this detail, and I have what is surely a very dumb question. Both titanium and carbon fiber are, afaik, known and used for their strength to weight ratio; so aerospace is a natural application. But in deep sea diving is weight a factor at all? Could one just build vehicles with, I don't know, a 30 cm thick steel plate?

> But in deep sea diving is weight a factor at all?

You need to be able to attain both positive and negative buoyancy, which constrains density within a range, right? That limits design choices like “giant block of steel with a tiny passenger cavity”.

It's super easy to add buoyancy by attaching it to the hull outside the pressure vessel. James Cameron's design uses a metal pressure vessel with an advanced foam composite outside of it for buoyancy.

And of course he used McArthur, of all the people, as a reference...

Well, he now will be remembered, just for inevitable Darwin award

>which seems to now have been in a pretty active role in the demise of the Titan.

I know little about the topic but it sounds terribly early to rule what exactly had 'a pretty active role' in the incident. Is it not?