Geosim experimental results of high-speed catamaran: co-operative investigation on resistance model tests methodology and on ship-model correation

The paper summarizes the results of a high speed catamaran model test program jointly performed at INSEAN (Rome Towing Tank) and at Naples University facilities. Systematic calm water tests were carried out on three geosims (model scale λ = 7,13 and 26) of s hard chine symmetric catamaran operting in the Naples Gulf, whose dimensions at designed load condition are: length L = 35.867 m, breadth B = 11.334 m (demihull B = 3.30 m); draught T = 1.58 m, displacement Δ = 137 t, separation length ratio s/L = 0.224. The greatest model of 5.12 meters was tested in the Rome Towing Tank (453 m x 13.5 m x 6.5 m), the other two models were tested in Naples Towing Tank (140 m x 9 m x 4.20 m). The experimental research carried out on the catamaran and on its demihull was undertaken with the goal to obtain indications of the effect of towing line position, on the resistance components scale effects, on the resistance interference phenomena, on the most suitable ship-model correlation and on the methodology for the evaluation of additional resistance due to appendices. The results obtained, analysed and discussed, can be considered a contribution to the solution of the above mentioned problems.