In the current study a variable speed pump controlled hydrostatic circuit where an underlapped shuttle valve is utilized to compensate the unequal flow rate of a single rod actuator is analyzed. Parameters of the shuttle valve are included in the system analysis, rather than treating it as an ideal switching element as handled in literature. A linearized model of the system is obtained. An inverse kinematic model, which calculates the required pump drive speed for a desired actuator speed and given pilot pressure input, is formed. A numerical stability analysis program is developed, and the stability of all possible shuttle valve spool positons is determined. The theoretical findings are validated by non-linear simulation model responses.

In this study, the initial hydrostatic stability, the hydrostatic stability and the structure realibility of three different barge-shaped vessels is simulated and evaluated in order to see which of the vessels would be the most optimal to use for deployment of wave energy converters, WECs. The vessels differ in their hull type: Bulbous-bow hull vessel, Barge hull vessel and Modified-barge hull vessel. In order to do the evaluation, the hull of each vessel is designed in DELFTship and further design is proceeded in SolidWorks 2014. Structural strength analysis is performed in SolidWorks 2014 and hydrostatic properties are simualted in Ansys Aqwa 16.0. The collected results are pointing at that the Modified-barge hull vessel is slightly superior to the others in terms of hydrostatic stability, while the structure stability is equal. The results of this study will provide a foundation for further evaluation of vessels capable of deploying wave energy converters.