R/V Athena Model (5365) Response in Waves

Developing a computational approach to predicting the response of high-speed craft to both global and local impact loads while operating at sea to allow for increased structural optimization.

October 1, 2022

Naval Surface Warfare Center, West Bethesda, Maryland

Current structural design methods for high-speed naval craft rely heavily on empiricism. Though these methods have been employed reliably for a number of years, it is likely that an unknown level of conservatism exists in the prediction of both global and local impact loads to ensure the vessel’s structural design is robust.

A better physical understanding of the dynamic response of high-speed craft in seas would allow for increased structural optimization. To support this understanding, a computational approach to predicting motions and loads was proposed. The publicly releasable hull form Naval Surface Warfare Center Carderock Division (NSWCCD) Model 5365 (R/V Athena) was chosen to facilitate public release of results to various computational teams.

This model test was designed to provide a computational fluid dynamics (CFD) validation data set for semi-planing craft. The CFD predictions were evaluated in their ability to predict calm water performance, as well as motions and loads in regular and irregular waves. The measurements made during testing include:

Resistance, sinkage, and trim measurements for the model in calm water over a range of speeds.
Six degree-of-freedom (DOF) forces and moments acting on the model over a range of speeds and wave conditions.
Model motions and accelerations over a range of speeds and wave conditions.
Impact pressures over a range of locations on the model at different speeds and wave conditions for model validation.

This research focuses on the results from testing in waves.

Measurements of the Athena model operating in calm water, regular, and irregular waves were performed in the Deep Water Basin at NSWCCD using towing Carriage 2. The basin is approximately 1886 feet long, 51 feet wide, and 22 feet deep. Carriage 2 has a maximum towing speed of 20 knots (33.8 ft/s). A pneumatic wavemaker is located at the east end of the basin, with a wave absorbing beach at the west end.

Model 5365 is an 8.25 scale model of the R/V Athena, shown in the accompanying figure. The R/V Athena is a converted PG-84 Asheville-class patrol gunboat, which is operated out of Naval Surface Warfare Center - Panama City Division as a high-speed research vessel. The model, built in 1979, was constructed out of wood and fiberglass. The model has been refurbished over its lifetime. As part of its 2015 refurbishment, the tow-point of the model was moved to align with the center of mass. This translation of the tow-point allows for a more accurate representation of full-scale motions, more comparable measurements to the CFD simulations, and increased model performance in large waves.

This work was performed by Anne Fullerton, Jayson Geiser, Sarah Punzi, Jason Morin, Charles Weil, Don Walker, Evan Lee, Minyee Jiang, Van Lien, and Craig Merrill for the Naval Surface Warfare Center. For more information, download the Technical Support Package (free white paper). NSWC-0005