Semi-submersible Trimaran Hull Form Improvement to Reduce Ship Fuel Consumption

Indonesia has many tourist areas; therefore, it requires facilities to support the development of these regions. One of them is a semi-submersible trimaran ship that can explore the underwater scenery. Previous trimarans faced difficulties during operation due to the occurrence of forward flow in the area around the bridge, caused by water hitting the bridge area. This issue led to increased fuel consumption due to increased resistance. Therefore, optimization of the trimaran's hull is necessary to reduce the ship’s resistance and, in turn, reduce fuel consumption. The optimization is carried out by modifying the bridge distance (the distance between the main hull and the demi hull) and by changing the length of the demi hull. The slender body method is chosen to calculate the trimaran’s resistance because of the slender shape of the trimaran’s hull. This slender body method is then validated through towing tests to obtain the trimaran’s resistance value. The results show that for various bridge extensions, the lowest resistance value is obtained at a speed of 11 knots with a resistance of 31.6 kN. The resistance value for various reductions in the length of the demi hull at a speed of 10 knots is 36.5 kN. This indicates a reduction in the ship’s resistance, which can reduce fuel consumption.