Many people have likely noticed that the lower part of ships is painted red, while the upper sections might be green, blue, or gray. It turns out, this common color has an important technical purpose.
The red color of the hull below the waterline is due to the use of anti-fouling paint. This paint contains copper oxide—a biocide that prevents marine organisms like barnacles, worms, and algae from attaching to the vessel. If these organisms were to settle on the hull, the ship would become heavier, slower, and less fuel-efficient, and its propulsion systems would wear out more quickly.
The copper oxide in the paint makes it red and also effectively protects the hull during long sea voyages. In the case of military submarines, black paints containing carbon are used for protection against pressure and wear, but the principle remains the same: a clean and protected hull ensures the ship’s optimal speed and efficiency.
Thus, the familiar red color of ships isn’t just a tradition; it’s a practical solution for protecting the vessel and saving fuel.
