Dock Ladders Dock ladders are constructed of salt water resistant aluminum pipe and extruded aluminum channels (serrated to produce a nonskid surface with no sharp edges). Each step is heliarc welded on 12 inch centers with the top step located 12 inches below the deck surface. Channel size is 1/8" x 1" x 2-3/16". 21" wide overall. 5 steps long. This item is oversize and does not qualify for free freight.