Abstract: A marine vessel is provided which comprises a platform member, two parallel hulls disposed below the platform and adapted to be below the water surface when the ship is in operation, each of the hulls consists of an after section, a forward section having a smaller cross-sectional area than the after section and a central section having a cross-sectional area substantially smaller than that of the forward section and supported only by the junctions with the forward and after sections. Both forward sections and both after sections are joined to the platform member by strut-like members which are tapered so that their waterplane areas increase rapidly between the waterline and their junctions with the platform member.