I have to get floating docks for my 1994 Hunter 19 waterballast. The slip is concrete pier on one side(steel posts)and ropes to an outer post on the other side(1 far outer post). The slip is 12' x 30'. Presently the boat is tied off in 4 directions but I worry whether the docking lines would break, as there is plenty of wind and current there. Does anyone have any designs showing or telling me how many float drums and what sizes I need? Also, does anyone know where I can buy some used? I am very much appreciative of any suggestions.