checked last night this time saw foot prints going out from the boat launch 150feet or more, a friend and i drilled about four holes 5 feet apart, too dark to take a measurement so i used my middle finger and thumb to try and get an idea and it felt pretty thick , hopefully its black ice it was definately more then 4 inches in the holes..i definatley wont be going out til it freezes longer especially with the weather being so mild.