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Comment by _hyn3 | Hacker News Reader

Not at 1atm. The air was pressurized.

It doesn’t sound to me like the boat actually sank. In the article it mentioned that they heard the rescue helicopter from within. Wouldn’t that imply that the pressure inside would be one atmosphere? Am I thinking about the physics of this wrong?

Sound does carry remarkably well through water - but you're right. The ship capsized, but the hull held enough air that it stayed afloat.

It was floating upside down.

There is a picture towards the end of the story.

Mostly, the weight of the boat pulling down would compress the air bubble a bit, probably not very much though.

The pressure of any trapped gas will be equivalent to the depth of the lowest level containing air - so if the bottom of your air bubble is a meter below sea level, your pressure will be 1.1 atm.

How is that? It was at surface pressure and then rolled over.

If the booyancy of the trapped air was a significant factor in the boat not sinking, then the air would have been at pressures over 1atm.

Put a barometer in an empty, upside-down cup. Force the upside down cup 1/2 way down into the water, trapping the air inside.

The barometer will be at the sea pressure of the bottom of the cup.

Makes sense if the glass is perfectly vertical, air can’t escape and force is applied from the top. But if you capsize a glass by slightly turning it on its side such that most of it sinks and the air escapes by water displacement you would get some compression on the remaining air but its unclear how much.

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