Does getting a base tan really prevent sunburn?
Getting a base tan is never a wise idea to prevent sunburn. First, a tan is just a sign of skin damage which over time speeds up the aging process and increases your risk for skin cancer. There is absolutely no safe and acceptable way to tan, unless you are doing it the sunless way.
While having a tan may give you a minimal amount of protection before you start to burn, it is not worth the risk of exposure to damaging rays. Tanning beds are even more dangerous than natural sunlight, since they emit UVA rays which penetrate deeper into the skin than UVB rays, causing significant damage.