Convoys were made up of whatever ships were available. In general, there was no need to convert ships, as they would be carrying the same, or similar, cargoes as they had prewar. This meant that the typical convoy could be made up of a wide mix of ships, including both pre-war shipping, and new, wartime builds. However, there were a considerable range of standardised designs beyond the Liberty Ships. The oldest were the so-called 'Hog Islanders'. These were the result of a shipbuilding program set up in the USA during WWI, pioneering the use of prefabricated sections in shipbuilding. They were named for the program's main yard, at Hog Island, Pennsylvania. While they were built for WWI, the vast majority were completed after the war, and they were still in use for WWII. From 1939, the British built a number of different standardised designs as 'Empire' ships. 'Empire' ships were given names starting with Empire, and they could be built to a number of designs, depending on role - there were slow and fast freighters, ore freighters, heavy lift freighters, tankers, coasters, and so on. In the run-up to the American entry to the war, the United States Maritime Commission produced a number of standardised designs; four cargo designs, C1-4, and three tanker designs, T1-3. These were effective, but inefficient to produce, and as such, would ultimately be replaced by the Liberty Ships. These were, in turn, based on the 60 'Ocean' ships, produced in the US for British use. Similar ships were produced in Canadian yards; these were given names starting with 'Fort' if they were operated by the British, and 'Park' names if operated by the Canadians. Finally, the Liberty Ship was supplemented by the Victory Ship, a larger, faster design.