Underwater Docking Stations (DS) offer Au-tonomous Underwater Vehicles (AUVs) a practical solution to extend mission duration and reduce deployment costs. However, existing designs need adaptation to accommodate Intervention-AUVs (I-AUVs). This paper presents the foundational development of a dedicated docking station for the Girona I-AUV. We explore multiple design iterations, including funnel-shaped, hybrid, and vertical models, to arrive at the final configuration. Then; the selected design undergoes comprehensive evaluation in simulations. Our assessment focuses on three critical parameters: structural size, manufacturing cost, and operational feasibility. The results demonstrate that the vertical docking approach optimally balances these requirements.

Traditional 2D optical markers degrade quickly in underwater applications due to sediment accumulation and marine biofouling, becoming undetectable within weeks. This paper presents a Three-Dimensional Binary Marker, a novel passive fiducial marker designed for underwater Long-Term Deployment. The Three-Dimensional Binary Marker addresses the 2D-markers limitation through a 3D design that enhances resilience and maintains contrast for computer vision detection over extended periods. The proposed solution has been validated through simulation, water tank testing, and long-term sea trials for 5 months. In each stage, the marker was compared based on detection per visible frame and the detection distance. In conclusion, the design demonstrated superior performance compared to standard 2D markers. The proposed Three-Dimensional Binary Marker provides compatibility with widely used fiducial markers, such as ArUco and AprilTag, allowing quick adaptation for users. In terms of fabrication, the Three-Dimensional Binary Marker uses additive manufacturing, offering a low-cost and scalable solution for underwater localization tasks. The proposed marker improved the deployment time of fiducial markers from a couple of days to sixty days and with a range up to seven meters, providing robustness and reliability. As the marker survivability and detection range depend on its size, it is still a valuable innovation for Autonomous Underwater Vehicles, as well as for inspection, maintenance, and monitoring tasks in marine robotics and offshore infrastructure applications.