transversal trawl winch forward of the superstructure. A derrick may be a boom rigged to the foremast to help shoot the cod end from the side. Until the late 1960s, side trawlers were the most common deepsea boat used in North Atlantic fisheries. The 1950s side trawler, Ross Tiger is preserved in Grimsby. These trawlers were used for a longer period than other kinds of trawlers, but are now being replaced by stern trawlers. Some side trawlers still in use have been equipped with net drums. Stern trawlers Stern trawlers have trawls which are deployed and retrieved from the stern. Larger stern trawlers often have a ramp, though pelagic and small stern trawlers are often designed without a ramp. Stern trawlers are designed to operate in most weather conditions. They can work alone when midwater or bottom trawling, or two can work together as pair trawlers. The superstructure is forward with an aft working deck. At the stern are gallows or a gantry for operating otter boards. Any fish processing usually occurs in deck houses or below deck. A wet fish stern trawler stores the fish in ice or sea water which has been refrigerated. A freezer stern trawler stores the fish in frozen boxes or blocks, and a factory stern trawler processes the catch. A pelagic stern trawler may use fish pumps to empty the codend. Freezer trawlers The majority of trawlers operating on the high seas are freezer trawlers. They have facilities for preserving fish by freezing, allowing them to remain at sea for extended periods of time. They are medium- to large-size trawlers, with the same general arrangement as stern or side trawlers. Drawing (FAO) Wet fish trawlers Wet fish trawlers are trawlers where the fish are kept in the hold in a fresh/wet condition, in boxes covered with ice or with ice in the fish hold. They must operate in areas close to their landing place, and the time such a vessel can spend fishing is limited. Trawler/purse seiners Trawler/purse seiners are designed so the deck equipment, including an appropriate combination winch, can be rearranged and used for both methods. Blocks, purse davits, trawl gallows and rollers need to be arranged so they control the pursing lines and warp leads and in such a way as to reduce the time required to convert from one arrangement to the other. These vessels are usually classified as trawlers,