Hydrodynamics of Semi-Submersible Vehicle Hulls with Variable Height-Width Ratio in Deep and Shallow Water

Semi-submersible vehicles keep most of their hulls underwater while maintaining a small platform above the water surface. These craft can find use for both naval operations and civil transportation due to special properties, including the low above-water hull profile, reduced wave drag in some speed regimes, and potentially better seaworthiness. However, hydrodynamics of these marine craft is not well studied. In this work, computational modeling is undertaken to explore steady hydrodynamic characteristics of several semi-submersible hull variations in a range of speeds in deep-water and finite-depth conditions. The validation and verification study is conducted using experimental data obtained with a Suboff model in a near-surface regime. Parametric simulations are performed for this hull and two others generated by modifying the original Suboff geometry to produce narrow and wide hull shapes with similar volumes. The computational results indicate that the narrow hull excels in deep water, having lower drag and experiencing lower downward suction force and smaller longitudinal moment. However, in shallow-water operations, the narrow hull exhibits noticeably larger resistance than other hulls with the same displacement due to smaller gap between the hull and sea floor. Main hydrodynamic characteristics of the studied hulls and illustrations of wave patterns are presented in the paper. These findings can be useful for designers of semi-submersible vehicles.