Truly the concern is almost zero with properly installed thru hull underwater lights. When was the last time anybody heard of a boat sinking because of, say, a failed thru hull transducer? I mean really, there are hundreds of not thousands of boats out there with thru hull UW lights and you just don't hear or read of any on going issues with them. If they were a big concern or prone to failure I'm sure the insurance companies would be upping people's premiums who install them. And that is not happening.