During the early 1970s, climbers Billy Westbay and Bruce Hawkins created the first portaledges by re-appropriating steel and canvas cots stolen from park lodges in Yosemite. These were a vast improvement from single point hammocks with regard to comfort, but they were not collapsible and weighed up to thirty kilograms (almost three times the weight of today's models). During this period climbers also used Submarine Ledges, made from U.S. Navy aluminum tube cots that had been purchased from army surplus stores.