Research, in order to breakdown the resistance components of multihull (catamaran and trimaran) form, has been carried out worldwide. Almost all of the work is focused on the resistance investigation in deep sea condition. The current work is concentrated on the investigation of the effect of water depth, namely deep, medium and shallow waters, into the total resistance of catamaran and trimaran configurations. Experimental investigation using ITS model were carried out in a towing tank (of 50m length, 3m breadth and 1.8 m water depth) at various hull separations (S/L= 0.2, 0.3, and 0.4) and various speeds or Froude Numbers. Special considerations were given to medium and shallow water depth because the Froude Numbers are based on water depth and not based on ship length such as in deep water condition. Computational Fluid Dynamics (CFD) investigation using a CFD code called Tdyn was also carried out to validate the results of the experimental investigation. The experimental test results compare well with CFD analysis and comparative studies with other published data strengthen the findings.