SEN0301 ME007ULA WATERPROOF ULTRASONIC SENSOR

I have bought a set of those sensors to monitor distance to the water from the deck level of a moving ship. The sensors should obviously be well above the water to function properly, but what would happen if they occasionally get splashed with salt water? Would they resume operations after some time on their own, should they be professionally cleaned after every single water splash or would they simply die on the spot? In which sense are they "waterproof" - IP62, IP64 or IP65?