Two things come to my mind.
First if these units would work the big ship industry would already know. These folks spend millions on antifouling, and more for the dry dock
time required. Even if these units just extend the lifetime of antifouling by a small percentage they would deploy such units on a global scale within a very short time frame.
However they don't. your chances of success are pretty much nil.
Second if I understand correctly these are devices inducing strong ultrasonic vibrations into the hull. What does a strong permanent ultrasonic blast do to fibreglass? Could this weaken the internal structure over time? I don't know.