 Wartime experience quickly showed MAS usage was heavily affected by sea conditions; the Regia Marina began searching for a more seaworthy alternative.The solution came with the acquisition of six captured Yugoslavian motor torpedo boats, built by Lürssen of Germany in the 1930s after the early Kriegsmarine "Schnellboote" design; the boats were re-designated "MAS 3 D" to "MAS 8 D" and pressed into Navy service.Though these early examples were slower than their Italian counterparts, the S-Boote were able to operate in rough seas, thanks to their rounded hulls.