Catamaranot. Two hulls or not two hulls?
Savoia Marchetti S.63 The Savoia Marchetti S.63 was an attempt to reduce the catamaran-configured S.55 to a central monohull seaplane, because the h igh command of the Italian Regia Aeronautica, initially, did not like the twin hull arrangement proposed by SIAI. S.55 (for comparison) The new seaplane maintained the engines and the wing of its twin hull predecessor , minus the central section and the twin boom tail arrangement. The mono-hull prototype of the S.63, that was designed for a military purpose, featured a gunner-observer bow hatch with a machine gun. The pilots sat side by side just forward of the leading edge, where the fuselage presented a marked step down, that is visible in the top photograph. In view of the success that the S.55 was beginning to enjoy, after the military evaluatio...