We may be future colonists of Mars but with the way we talk, you would think it's still the 18th century.
Sailing ships were the cutting edge technology of the 18th century, and the shipbuilding boom spawned many phrases that we still use today.
Loose cannon: Today, an unpredictable person. Then, a literal unsecured big iron tube that was going to hit something and cause a lot of pain.
Batten down the hatches: Today, get ready for trouble. Then, literally get an iron bar to cover the door of a ship for terrible weather.
All hands on deck: Today, There's a problem and we need everyone here now. Then — same, except an actual ship's deck.
Show one's true colors: Today, a dishonest person who reveals who they really are. Then, a ship flying a fake flag to confuse enemies. Pretty much the same.
Learn the ropes: Today, learn the rules and skills of a job. Then, literally learn how to tie and use ropes. This was important to keep a tight ship — which currently means a strictly managed organization, but back then might mean the difference between a ship that had been properly sealed for leaks and sinking in the ocean.
