Inside a submarine, only two places use red lights. One is the berth and the other is the control room. Under ordinary conditions, all the white lights are switched on to ease movement, alertness, and awareness of the crew. The same white lights are used when the submarine is present on the surface, at the port, or even when submerged. So, we have two questions. In what conditions are the red lights used, and why are they used? We look into these curious queries!
Airport control towers, planetariums, and movie theatres use red lights to help people’s eyes adapt from light to dark. The idea that red light reduces your ability to see in the dark is a lie. In fact, the presence of red light helps you adjust quicker to darker spaces.
Our eyes are not very sensitive to longer wavelengths. As a shorter wavelength, red light helps submarine crews see their instrument panels in the darkness. Without the red light, their adjustment wouldn’t be so smooth.
Another reason for using red light is to stop light coming out of the submarine’s periscope. Submarines shift to red light when it’s dark outside and crew members need to use the periscope or go on watch duty. Although blackout blinds cover the scope, there is still a chance of light being emitted from the other end of the periscope. This light can be seen from miles away, which, if noticed, would cause havoc!
So, there you have it. Submarines use red light not only for its ability to help sailors adjust their eyes in the dark but also to remain unseen in the deep, dark blue.