# Design and Study of a New Wave Actuator for a Boat
## 4 Conclusions  
A novel design for a wave actuator for boats is presented in this paper. The wave actuator is installed beneath the boat hull and converts the hydrodynamic forces generated by rising waves on the boat into translational thrusting forces. The compressed water in the tank of the wave actuator is expelled by the exerted wave pressure on the actuator, and the water thrust out of the nozzles propels the boat forward. The dynamics and hydrodynamics of the new wave actuator are presented using the second-order differential equation in this paper. Based on the modeling of the wave actuator, the analyses of the energy conversion capacity of the wave actuator are performed. Computer simulations are performed to evaluate the performance of the new wave actuator for the boat. The simulations are carried out based on specific boat conditions and corresponding sea environments, as the following: the boat has a waterline length of 7.13 m, the waterline width is 2.26 m, the draft is 0.5 m, and the weight of boat displacement is 4397.9 kg. In four cases of simulation for regular waves, the wave frequency ranges are 0.4-0.2 Hz, the wavelength ranges are from 9.758 to 39.033 m, the wavenumber ranges are from 0.644 to 0.161, the wave height is 1.25 m, and the wave amplitude is 0.625 m. Of the four cases, the best result is observed in Case 2, where the wave frequency is 0.3 Hz, the water tank has a damping coefficient of 20, the spring coefficient is 20, and the boat speed is 2.06 m/s. Calculating the intersected area between the boat motion path and wave motion is significant. The 0.3 Hz frequency shows that the intersected area is the most suitable, avoiding the overly intense wave interactions that reduced conversion efficiency in Case 1, while also preventing the smallest area seen in the synchronized boat and wave motion in Case 3. Additionally, Case 4 is rejected because the low initial velocity means that the wave energy is purely converted into propulsion without the need for additional thrust from other engines. The most influential factors are wave frequency and initial velocity, which are clearly observed from the amplitude graph, where wave peaks clearly depict energy conversion capability. In Case 2, the boat achieves a cruise speed of 6.098 m/s with 67.9% wave-to-propulsion efficiency. However, this warrants further analysis, as the design and equations were developed and simulated under idealized conditions. The intersected area suggests that the wave force acting on the boat is perfectly converted with no energy loss. The nozzle  
Figure 16: Amplitude graphs for Cases 3 (**a**) and 4 (**b**). is assumed to achieve maximum efficiency, focusing only on the nozzle radius without describing the water flow path shape. Nonetheless, this high efficiency highlights the actuator's potential for effectively harnessing wave energy for boat propulsion. While this study presents a novel wave actuator system with promising theoretical performance, it is important to acknowledge its limitations. Due to the unique design of the actuator, there are no directly comparable systems or published results available for validation. Experimental data are currently unavailable, and the study relies on numerical simulations to demonstrate the feasibility of the concept. Our current work focuses on regular waves as an initial step to establish a clear theoretical foundation for the actuator's dynamics and energy conversion capabilities. Future work will extend this analysis to more complex conditions and include experimental validation in a controlled environment, such as a wave tank, to confirm the practical applicability of the actuator. In particular, CFD simulations will be conducted to replicate fluid-structure interactions under realistic operating scenarios [28]. These simulations will refer to heave decay tests [29], as demonstrated in recent computational studies of floating sub-platforms, to better characterize hydrodynamic damping effects.