Hydrodynamic Forces On ROVs Near the Air-Sea Interface

The control and operability of remotely operated vehicles (ROVs) are strongly influenced by their hydrodynamic characteristics especially in the near-surface wave-affected zone. This project has considered a 1I4-scale model of a Super Scorpio, representative of current bluff-body workboat ROVs, together with simpler geometrical configurations, to determine the hydrodynamic coefficients in this region and the generality of these results to other vehicles. Proximity to the air/sea interface increases the inertia and drag coefficients, compared to the standard values based on conditions of deep submergence. In addition, for steep waves, the present research proposes the use of two values of inertia coefficient per wave cycle. This may be contrasted against the more usual practice based on one (averaged) value which leads to an underestimation of the peak hydrodynamic forces.