gdcutting

Rush's stated reason for using carbon fiber over materials (ti or steel) which are much more accepted in submersible design world was to save money. A question I haven't seen asked elsewhere is, how much money are we talking about saving here? Clearly in retrospect whatever amount of money we're talking about is worth a lot less than five human lives and the recovery costs, but of course Rush didn't think his design would fail or he wouldn't have done it. I would like to see an informed estimate of the cost difference between other hull materials given the Titan's size. Obviously there are a lot of choices of material, and information that isn't publicly available about the design, but I'm sure there are some folks out there who could give a knowledgable comparison which would help us to quantify the decision-making process here.

Sure, titanium or appropriate steel would be more expensive, but it's hard for me to imagine that we're talking about an amount of money that would simply make the project unprofitable, since there are plenty of other submersibles out there built without carbon fiber hulls, and those companies are making money. Even if we were talking about a difference of some hundreds of thousands of dollars (can't imagine it would be more) between the two materials, we're still talking about life-or-death here (and one of those lives was Rush's). And while obviously the overhead costs of operating a submersible business are very high, these customers are paying $250k/dive. It seems like if Rush had said to people, "We went with ti over carbon, which would have saved money, but now we can be much more sure that the material won't fail catastrophically," anyone with that kind of money would have been happy to pay an extra, say, $10k or $20k or $50k/dive to make sure that they didn't die.

My take on the situation is that the money was less important in his calculus than the ego aspect of wanting to be seen as a maverick and showing the rest of the sub engineering community that he was right against their conventional wisdom. Being seen an 'innovator' seems to have been a powerful motivation for Rush. Often the actual amount of money matters much less to people than the 'animal spirits' (to use Keyne's phrase) underlying those decisions. Maybe I'm just trying to give Rush the benefit of the doubt, since putting people's lives at risk just so he could further enrich himself (and it doesn't seem like we're talking here about a guy that could barely afford lunch) is just evil. Maybe he was greedy and cheap (which doesn't necessarily mean that he didn't have a lot of good qualities).

Thoughts? I'd love to see someone run the numbers.

Testing is costly in terms of time and money, particularly with a submersible. It's one thing to test a piece of code, but testing a submersible under realistic conditions means basically arranging a full mission for every test run (which is hugely expensive, requiring a support ship, etc.). There's no such thing as perfect safety, which always has to be balanced with cost. I'm not saying Rush's approach was sound (he apparently eschewed more thorough testing) but testing that submersible a hundred times surely would have been cost-prohibitive.

Also the Titan did successfully complete ~20 deep dives from what I've read, so the design was apparently sufficient to stand up to the pressure more than once, meaning even a non-trivial testing program might not have detected the problem. Unfortunately the problem (as many have stated) seems to be in the choice of carbon fiber, which (particularly when taking into account the interfaces with other materials) will weaken over time even if the initial flaws are very small. All materials experience fatigue but the problem is much worse with carbon particularly under those kind of pressures.