Same exact spots I get on my boat when it sits in my slip, down at LotO. Its electrolysis. Somewhere current is being released into the water. You should see mine after being in the water for straight 6 weeks. I turn my batteries off completely, when I'm done running. It could be coming from another boat, or our dockhouse, I wish I knew. After the Electrocutions in the water at our lake, this year, the condo association had the boathouses tested and they were all fine.

I will be re-polishing the bottom this fall, (All the Sharkhide in the world won't stop that) and buying a lift for the slip real soon. I'll get a pic for you when I get out to the boat, later. So we can compare our boats. Its not a fault of the Premier, because it happenend to my Manitou, as well. Same exact damage. Stripped off the Sharkhide, wetsanded with 600 grit, it smoothens right out. Then polished and re-Sharkhided the Manitou, took me about 3 hours, to fix that one. The Premier won't be as bad, because I just go down to the trailer bunks, on it. But still, its time, off the water when I can be on it.