do Cherenkov radiation move ftl in water?

No, Cherenkov radiation does not travel faster than light in any medium, including water. Cherenkov radiation is produced when a charged particle moves through a medium faster than the speed of light in that medium, causing the emission of a characteristic blue light. However, the speed of light in water is still slower than the speed of light in a vacuum, so Cherenkov radiation in water does not travel faster than light.