The research was carried out by numerical methods of wave formation and resistance for an extra-capacity displacement catamaran in the range of Froude numbers from 0.181 to 0.3 and the range of relative clearance from 0.3 to 0.55. Symmetrical hulls and hulls with an inner flat side, developed on the basic lines of M. Ya. Alferiev were used. The ship wave heights generated by the hulls of the catamarans and their resistance were compared with the corresponding simulation results for a large mono-hull vessel with a hull width equal to the total width of the catamaran. Numerical simulation was performed in the FineMarineTM software package. It was found that the resistance and wave heights from a mono-hull vessel and a catamaran with a flat inner side exceed the resistance and wave heights of a catamaran with symmetrical hulls.