The red color applied to the bottom of the ship is a layer of anti-rust paint to prevent seawater from corroding the bottom of the ship.
But in fact, there are other reasons and functions for painting red.
The first reason is to prevent all kinds of animal parasitism. There are various marine animals in the sea, and some of them, such as oysters and anemones, like to cling to the bottom surface of the ship and grow and reproduce very quickly. This not only increases the weight of the ship itself, increases the resistance when sailing, but also affects the smoothness of the bottom shell. Therefore, in order to prevent these organisms from parasitizing, some toxic substances are added to the anti-rust paint painted on the bottom of the ship, such as copper oxide, mercury oxide, etc. As these toxins slowly exud, marine organisms no longer grow, allowing the bottom of the boat to remain clean for a long time. Secondly, today's shipbuilders will also deliberately add red pigment to the paint, in order to remind people that this is a toxic substance, do not touch it!
The second reason is that it is easier to see the position of the hull. The red color is very conspicuous in the blue ocean, so that it is easier to see the position of the ship's waterline and the load status, which is convenient for observation and measurement.