Unless you know about boats or you have an eagle eye, it might have escaped you that a lot of ships are painted red on the bottom.
And there’s a reason for that…
Early sailing ships often painted their hulls in copper or copper oxide paint to protect against barnacles and worms that eat wood and this gave the hulls a red tint. It’s best to keep those things off the ship so it doesn’t get weighed down.
Biocides can be combined with any color of paint these days but a lot of people still paint hulls red because they like to keep the tradition.
The red paint also helps people choose the load of the cargo on ships because the ship will be lower in the water and the hull will be more submerged in the water.