Boat decals

So a friend of mine bought a boat. First season with it and the decal on the sunny side crumbled. I have told him his most likely only option is to get a custom water line cover for it or remove the decals before they hologram on him. He really likes the decals though. His boat is red with black graphics on it. (Both of which are not in his favor in my opinion with what happens to red turning to pink)
So my question is..is there anything out there coating wise that will help him out? I am just a weekend warrior detailing my own vehicles. Just put Gyon on my wife’s SHO and getting ready to do my Mustang and F250 crew cab. So I have some knowledge of. Ceramics but wonder can they go on decals and will they help? I just have not found a definitive answer.
Thanks for any input, David