A study is conducted to test the dynamics of the 33ft Wave-Adaptive Modular Vessel (WAM-V) when outfitted with different suspension systems.  Instrumented with an array of sensors, the vessel is tested with two different suspension arrangements to characterize how they affect WAM-V dynamics, and to ultimately select a suspension that is most suitable for the 33ft WAM-V and other vessels that are planned for the future. Optimizing the suspension can reduce the magnitude of accelerations at the payload tray, benefiting both the operator and the payload.  Reduced accelerations can significantly improve comfort and risk of injury to the operator, while also lessening the likelihood of any damage to any sensitive cargo onboard.  The stock suspension components are characterized through in-house tests conducted at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech (VT).  Based on the stock characterizations, new suspension components are chosen to better fit the needs of the 33ft WAM-V. Sea trials are conducted with both suspension systems at the Combatant Craft Division (CCD), a division of the Naval Surface Warfare Center, Carderock Division (NSWCCD), in Norfolk, VA to quantitatively and qualitatively determine the differences between the two suspensions.  The 33ft WAM-V is instrumented with a series of accelerometers and potentiometers for measuring accelerations and displacements.  The data is analyzed for the sea trials conducted at CCD and the results of the analysis indicate that the suspension selection can significantly affect the transmission of shock and vibrations from the pontoons to the operator or payload tray.  Both suspensions are able to mitigate a significant amount of the shocks seen at the pontoons, however, the results do not definitively show which suspension is the better of the two.  This is due to the fact that each suspension is not subjected to the exact same wave conditions, and  therefore the resulting suspension dynamics vary.  For instance, during a 2-foot wave event, the new suspension attenuates more shock than the stock suspension, 76% versus 71%.  However, during a 4-foot wave event, the stock suspension attenuates more shock than the new suspension, 66% versus 60%. Additionally, the suspension selection can significantly influence the ride height.  The stock suspension provides a 70/30 ratio between extension and compression stroke, while the new suspension provides a 50/50 ratio.  The more balanced split between the extension and compression strokes allow for better utilizing the total available stroke for the suspension in both directions.  This significantly reduces the resulting high-g impacts since the suspension does not frequently bottom out when the vessel is subjected to a large wave. It is recommended that the results of this study be extended through laboratory dynamic testing that allows for more repeatable dynamic events than sea trials in order to better establish the influence of each suspension parameter on the vessel dynamics.  Such tests will also allow for a better understanding of the dynamics of the vessel in response to various inputs at the pontoons, both subjectively (visually) and objectively (through measurements). / Master of Science

Wind propulsion is a traditional way to propel ships over the oceans. In the recent development towards more sustainable shipping, sailing is considered in the industry again with high momentum. For a modern merchant ship, the aerodynamic forces generated on the particular rigging are unusual. Tailored research and experiments are required to understand their influence on the ship’s sailing behaviour. This work concerns the aerodynamic interactions on a model-sized car carrier with four 360° rotatable, symmetric, rigid wings aligned along the centreline on deck. Differential pressures on the wings are measured to capture the generated normal forces. In a comprehensive post-processing, data recorded in systematic experiments at two apparent wind angles were evaluated. A comparison for the different wing positions on board the model shows stronger interactions in upwind sailing conditions than when reaching. The two-dimensional data prove a significant influence of the hull in the normal force profiles over the wing span. The results of this work indicate that the aerodynamic conditions while sailing have to be attentively considered for efficient wing trimming. / Under en lång tid användes främst vindkraft för framdrivningen av fartyg. Det är först på senare år att seglingskonceptet har fått ett nytt uppsving inom marinindustrin med tanke på dess hållbarhet. För fraktfartyg är de aerodynamiska krafterna vid segling ovanliga. Därför behövs särskild forskning och experimentella metoder för att förstå hur de påverkar fartygens seglingsbeteende. I detta arbete undersöks aerodynamiska interaktioner på en modell av ett biltransportfartyg med fyra symmetriska, 360° roterbara vingsegel på däck längs midskeppslinjen. I systematiska experiment på två kurser mot vinden mättes differenstryck över vingprofilen för att undersöka de genererade normalkrafterna. En jämförelse av data från de fyra olika vingpositionerna och båda kurserna mot vinden visar att de aerodynamiska interaktionerna är starkare på kryss än vid halvvind. De upmätta profilerna av tvådimensionella normalkraftkoefficienter över vingspannet visar på betydande aerodynamiska interaktioner med fartygets skrov. Resultaten av detta arbete visar hur viktigt det är med en grundlig undersökning av strömningsförhållandena för en effektiv segeltrim.