Experimental investigations into the resistance components of asymmetrical catamarans with variation of hull spacing and stagger

Interference of the resistance components of round-bilge catamaran forms has been investigated experimentally. The model hull forms comprised an asymmetrical catamaran along with laterally separated and longitudinally staggered demihull configurations. To this aim, a series of tests on the models were conducted at the Towing Tank of the Indonesian Hydrodynamic Laboratory (IHL) over a speed range corresponding to Froude number up to 0.65. In this paper, experimental results are presented in tables and graphical form and the resistance characteristics and interference effects are discussed and compared with other published data. The test results show favourable resistance interferences for some hull spacings and unfavourable for others, depending on speed. Favourable reduction in resistance has been observed at Fr> 0.50 for the hull spacing and at Fr> 0.40 for the staggered catamarans. While the staggered catamaran hull form is not immediately practical, it is of great interest to understand the wave field interaction between the demihulls. These results may prove useful for designers at conceptual or preliminary design stages.