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This is 99% invisible I'm Roman Mars. Oh, what here?

If you look at the outer hull of commercial ships,

down by the waterline,

you might find a painted circle bisected with a long horizontal line.

This simple marking is called the load line, or as I prefer, the plumsole line.

And not to oversell it but this elegant graphic design has saved

thousands of lives. This is one of my favorite examples of design because what I

really like in the world is when you can find a massive problem

that definitely needs solving and with some thought you can solve it with something as simple

as a circle with a line through it. I just find it amazing. That's what I'd like to do with my career.

That's Tristan Cook.

And I'm a human factors engineer, so that means that I look at the way that people interact with their environment

and figure out how that will affect their behavior.

Tristan also curates an outstanding blog called Humans and Design.

So anyway, the massive problem that needed solving in the 19th century that Tristan is referring to was the huge number of

British ships sinking in the ocean because they were overloaded and in disrepair

...