lathes, and welders for heavy repairs, plus an optical shop and clockmakers to repair binoculars, sextants, marine chronometers, optical rangefinders, and fire-control system computers. These tenders operated stills and electric generators to supply fresh water and electrical power to destroyers moored alongside for boiler repair. Each increment of size enabled destroyers to carry more of the personnel and equipment previously found on the tender. Destroyers reached the size of cruisers during the Cold War, and with that size acquired a cruiser's capability for independent action. Surviving tenders became functionally indistinguishable from repair ships. Some destroyer tenders were designed and built to attend a flotilla of destroyers, while others were converted from ships built for other purposes. Tabled below is a comparison of ships designed as destroyer tenders: See also List of United States Navy Destroyer Tenders (AD) Submarine tender Notes Sources Ship types Auxiliary depot ship classes