Subsea Towed Docking Cone for Launch and Recovery of Autonomous Underwater Vehicles

The increasing demand for efficient, cost-effective, and safe underwater operations has driven the development of advanced Launch and Recovery Systems (LARS) for Autonomous Underwater Vehicles (AUVs). This study presents the concept and functional design of a subsea towed docking mechanism, the Launch and Recovery Device (LARD), which addresses critical challenges in AUV recovery by establishing a secure physical connection underwater. The LARD features a funnel-shaped entrance and a frame with articulated struts equipped with adjustable clamps, allowing it to securely grip AUVs of varying sizes using frictional forces. The functional sequences for launch and recovery are outlined, detailing the system's ability to securely position, lock, and release the AUV while ensuring resilience under diverse environmental conditions. Conducting the docking procedure sufficiently deep below the free surface significantly mitigates the impact of wave-induced motion on the AUV and LARD as wave-induced particle motion diminishes with depth. This study analyses the influence of waves at different water depths using examples in the North and Baltic Sea sourced from the German Federal Maritime and Hydrographic Agency. The particle velocities were derived using Airy and Laplace wave theory, confirming that nonlinear term were negligible for the present study at the examined conditions. Relevant wave behavior is analyzed based on the distinctions between deep, transitional, and shallow waters.