A Lake Lanier group’s crusade to rid the lake of abandoned docks and vessels has hit some choppy waters as it works to dispose of a sinking houseboat that belonged to a late Flowery Branch man. The craft has sat on the shoreline near Sunrise Cove Marina in West Hall County since Michael Gilmer, 61, of Flowery Branch was found dead near it Sept. 23, said Joanna Cloud, executive director of Gainesville-based Lake Lanier Association. The boat started sinking and today, “the vessel is almost entirely underwater,” she said.