The Allied technical experts found much to praise about her design and construction. "Graph"s auxiliary machinery was on rubber mountings, making her stealthier by reducing sound transmission into the hull. The British and the Americans who examined "Graph" singled out her Zeiss periscope for particular praise. The American officers who carried out her initial inspection in Iceland recommended it be copied as quickly as possible for possible US Navy use. Her underwater acoustic equipment was found to be a sophisticated array of hydrophones that was significantly better than the British equivalents. The main criticism of the boat was poor and cramped crew accommodation, which would degrade crew performance on long patrols.