I don't know if the lift had GFCI or how old it was. Lifts have been around for a very long time. That lift may have been new or maybe not; I don't know.Did the boat lift have GFCI protection (like it should have)?
I've seen the service neutral/ground be at an elevated voltage from the waterway. When the mains were shut off, the voltage was still there, lift the incoming service neutral from the meter bus and it was gone. If that condition existed, having GFCI protection would not prevent the grounded boat lift from shocking those 2 boys. Was there an investigation to determine what the cause of the ESD was?
Edit: Since I observed that condition, I've driven 20' of ground rod near the waterway and tied it back to the service neutral for all jobs I work on. The PoCo does not consider this there problem (which I can't understand how it's not their problem).