Clay and we talking about how a Shadow Caster would do on the side of the boat. All the underwater LEDs are made to go underwater but Im not sure how they would handle the water pressure from the side. The water pressure from the side of the boat is WAY more than is at the transome of the boat. I has seen some large ships with headlight bucket style ports where underwater lights go. This keeps the light out of the flow of the water. Abyss makes a light that's made to run down the side of a boat like sail boats. Install them down the side of the boat would require a bit of forward thinking. You would need to design a way or system that would allow you to replace/repair the light in the event it was broke or dammaged and allow you to have a water proof disconnect at the lights. So there are some large hurdles to over come. That alone with the cost of like let's say 20 $600 lights. And some major install work. I have been thinking about it.
The Shadow Casters are real thin so they would work as far as not messing up the water flow down the side of the boat.
Im tempted to get a Shadow Caster and mount it on it's side and mount in our hot tub pointed at a jet and and run it for a few months and see how it's deals with water blasted at it from the side for some time.
If you mounted them just below the water line they would be out of the water when you were going fast and the water pressure was high so it might work real well