Ocean waste that continues moving in the water has been a problem until now. This has stimulated marine debris cleaning technology to emerge. This research sought to evaluate the effectiveness of waste collection using a monohull and catamaran fitted with a forward conveyor. The Reynolds Average Navier Stokes (RANS)-based numerical simulation research is used to predict flow pattern characteristics, velocity contour, wave pattern, pressure distribution, and ship resistance. The current research focuses on the impact of a round-bilge-type monohull and inner flat-type catamaran hull front shape on waste collection behavior by applying numerical methods. The multiphase solver numerical configuration supplied with OpenFOAM v2112 has been verified and validated using the Delft catamaran 372 with Froude numbers 0.3. The effect of free surface on resistance and flow characteristics was evaluated by comparing these two models. The results show the behavior of marine debris collection due to the flow characteristics of both models. The marine debris flows much more conveniently through the conveyor fitted in front of the catamaran model than in the monohull model. In addition, considering the front-side hull flow, the catamaran model is superior since marine debris is able to approach the ship easily. However, the monohull model is faster at bringing marine debris closer to the conveyor, particularly at the location in front of the conveyor.

Propulsion system is one of ship systems which require more attention, especially on propeller design. The propeller design greatly affects the ship speed. It is expected to be able to have maximum value of thrust coefficient and efficiency. Hence, the optimum design of propeller can be obtained by multi objective optimization process. In this study, a preliminary optimization is applied to B-series propeller with the Non-dominated Sort Genetic Algorithm-II (NSGA-II). The purpose of this study is to find out the optimum performance of B-series propeller. The thrust coefficient and open water efficiency are maximized in the optimization process which are then subjected to constraint function imposed by required thrust. The optimization is carried out to blade number Z=3 and Z=5. The population of design space is obtained after running the optimization program. The final optimum design parameter is considered using crowding distance value in the population. The result obtained by NSGA-II showed that the optimum design for Z=3 are B3-787, B3-314, B3-560, and Z=5 are B5-416, B5-501, B5-476 respectively. In addition, the Computational Fluid Dynamics analysis (CFD) is employed to investigate the characteristic of each propeller model by using Multi Reference Frame (MRF) approach. The CFD results showed that the highest thrust value of the Z=3 is 172.38 kN generated by the B3-787 whereas the highest thrust value of Z=5 is 168.80 kN generated by the B5-501 model.