Calm water towing tank experiments consisting of resistance tests and static and dynamic planar motion mechanism (PMM) tests are performed for a surface combatant with primary focus on the effects of hurricane scale headwinds. The experiments are designed to gain a better understanding of the physics of ship response to wind and to provide a validation dataset for an unsteady Reynolds-averaged Navier Stokes (RANS)-based computational fluid dynamics (CFD) code used for computing both air and water flow around a ship. Hurricane scale wind speeds are chosen to maximize the measurable effect of wind on ship forces and motions for a more definitive analysis and comparison with CFD. The geometry is the 1/48.9 scale fully appended ONR Tumblehome model 5613, which has length L = 3.147 m and is equipped with a superstructure. Tests are performed in a 3.048 × 3.048 × 100 m towing tank with wind generated by a custom built wind carriage towed ahead of the ship model. Air-stream velocity measurements indicate a maximum relative wind speed magnitude of 9.38 m/s with 6 - 7% uniformity and RMS values of approximately 4.5%. The effects of three wind speeds on static and dynamic forces, moment, and motions are analyzed. Results show that wind contributes significantly to surge force (approximately 46% at Fr = 0.2). Resistance data shows agreement with CFD computations with errors averaging approximately 4%. The drag coefficient above water is approximately 0.3 and generally decreases with increasing ship speed. Sway force and yaw moment are largely affected when the ship experiences oblique orientation to the flow. Forces and moment exhibit quadratic scaling with wind speed. Roll is the most sensitive motion to wind and is counteracted by it up to 1.8° for PMM test conditions. In addition, harmonic amplitudes of forces and moment data from dynamic tests are used to determine hydrodynamic derivatives for all three wind conditions following a mathematical model. The effect of wind on hydrodynamic derivatives is significant with changes on the order of 10 - 100%.

Individuals are affected by different biases and heuristics in different ways. This dissertation explores the two of these (underdog bias and self-rated performance) and their relationship with personal risk propensity in the South African investment professional community. To measure risk propensity in investment professionals, a new instrument was developed. This was tested against a risk measurement scale based on the original work in prospect theory. Both risk propensity measures found similar and comparable results in the investment professionals, and similar results when compared to other studies that studied risk propensity in a more general population and risk tolerance in investment professionals in Europe. Similarly, self-rated performance had comparable results to other studies on overconfidence bias and the better than average effect. Investment professionals, on average, think that they are better than their average peer. Underdog bias, or the headwinds/tailwinds asymmetry, had an unexpected result where the investment professionals felt they did not suffer from stronger headwinds and barriers compared to their peers. This was an unexpected result and may show that the South African investment industry feel more grateful than others to be where they are or, the sample may have triggered the boundary condition of underdog bias where individuals feel their personalised benefits more than their shared headwinds. Further testing is required in the same population as well as similar populations to confirm the boundary condition. The three constructs were tested to understand the relationship between them. In each of the three cases, there was no significant relationship between any of the constructs. The results were different to what was expected and, subject to further testing, may have found a blind spot in investment professionals where they believe that what when they are doing something they consider to be right, they do not perceive the increased risks associated with the action. These blind spots have an impact on how risk is managed investment firms and needs to be monitored to protect the overall firm. / Mini Dissertation (MBA)--University of Pretoria, 2018. / Gordon Institute of Business Science (GIBS) / MBA / Unrestricted