Effects of Body Geometry and Propulsion Type on Unmanned Underwater Vehicle Interactions with Marine Vegetation

Interactions with marine vegetation can disrupt unmanned underwater vehicle (UUV) mission success. Very little information is publicly available about the mechanisms causing these interactions or the consequences of them. This article compares the interactions between three different style UUVs and two different types of marine vegetation. Similar equipment and procedures were used to allow for the direct comparison between a GhostSwimmer, a REMUS-100, and a BlueROV2. Experimental test runs were conducted at different vegetation densities using either synthetic eelgrass or giant kelp. The resulting interactions depended on the vegetation type, vegetation density, propulsion mechanism of the vehicle, and vehicle geometry. Synthetic giant kelp caused a multitude of interactions including entanglement with the vehicle's body or propeller and blockage of the vehicle depending on the geometry and propulsion mechanism of the UUV. Eelgrass caused propeller entanglement, temporary speed reduction, and even blockage depending on the UUV. The use of an oscillating tail for propulsion coupled with a completely streamlined body appears to successfully mitigate adverse marine vegetation interactions.