entirely possible that the oxygen could have rapidly depleted, or the device could have sprung a leak. He said whatever happened, it’s likely that it was quick and painless.
I think that's wishful thinking. Chap on R4 this morning was saying that Stockton, at least, would know how to conserve oxygen (didn't explain), and that it could last longer than estimated. Also that the current was only 3-4 knots, so not that fast.
It's a sealed unit, so there must be some condensation from breath and sweat that they could drink, and there's always their wee - although I think current thinking is that drinking wee is not helpful if you're dehydrated.
It's harder with bangs though — you can't make a long and short one as easily. Rhythmical will probably be safer and easier to pick up as intentional. And if you're suffering from dehydration, lack of oxygen etc, the simpler the better I would think.
All the "bangs" are the same length when you're tapping. You don't make long bangs - you leave a longer space between them. Radio signalled SOS could do dashes, but they don't have radio, as we know.
I keep coming back to the toileting situation. They haven't eaten or drunk anything much so you'd hope that bodily excretions weren't too bad - but my god, the smell, and the ammonia.
The whole expedition seems so ill thought through, and badly planned - I can't believe they've got away with running these for so long without being pulled up on something - does no-one audit this kind of thing? I wouldn't even allow myself to be locked in a car in front of my house for 8 hours, with no manual override to get myself out, let alone in a sub a couple of miles under the ocean. They should at least give people the opportunity to decide to open the door and end things quickly for themselves, rather than die slowly and horribly from suffocation/dehydration/starvation/claustrophobia/madness/...