x, the Swimmer can remain operational subsea for up to three months at a time, without maintenance. This is achieved through careful hardware selection, and the implementation of multiple redundancies, fail-safe, and degraded mode layers throughout the system, such as redundant navigation sensors, communications, energy and electronics, fail-safe propulsion configurations, or redundant IMR tooling. Further extending its operating endurance to six months will result from two combined processes. Feedback from operating the first Swimmer systems on remote fields will help develop operating methods to minimizing failures. Collaboration with SPS manufacturers will help increase operating reliability, through careful design of the interfaces between the SPS and the Swimmer ROV. Secondly, iterative engineering analysis will lead to the selection of upgraded hardware, and the implementation of additional layers of redundancy and degraded functionalities.TO SURFACE CONDITIONSconditions, such as currents, waves and ice make deployment and recovery of an ROV uncertain, and risk harm to personnel and equipment, along with operating delays. Because the Swimmer is autonomous and hence untethered, launch and recovery may be done through a sequence of events decoupling the AUV from the ship. Launch may use a deployment ramp at the aft of the ship. The vehicle slides on the ramp and into the water, while the support vessel is cruising forward, preventing collision between the two. Alternately, the AUV may be deployed by the MSV to the seafloor while attached to its deck cradle - essentially a light version of a standard docking station - then the AUV can release from the cradle and navigate to the production field. The deck cradle is recovered by the MSV. Recovery of the Swimmer is initiated while it is on its docking station at the seabed. The surface vessel lowers the recovery apparatus attached to a crane or A-frame to the seafloor near the docking station. The Swimmer ROV captures the recovery apparatus, secures it to the AUV pad eyes on its top, and returns into the AUV. The AUV releases from the docking station and is hoisted to the surface as is done for standard ROVs. This eliminates most of the inherent risks of connecting a small marine vehicle to a larger one of a different dynamic behavior at sea. Furthermore, AUV recovery is not time critical, and may be postponed if necessary. In arctic areas, ocean surface formation of ice over subsea production fields can preclude operations, ultimately leading to IMR being interrupted or even worse, production facilities being shut down, until the ice recedes. Ice breakers may enable work, but with a significant price tag. Swimmer may be deployed by a surface vessel away from the area of ??ice formation, move autonomously to its docking station near the subsea facilities, and then operate regardless of surface conditions. The onboard inertial navigation system will guide the AUV towards the target docking station, assisted with acoustic positioning relative to the docking station when within a few kilometers range. When aintenance of the vehicle is needed, the vehicle will return autonomously to an icefree area for recovery., The Swimmer system can operate despite drifting icebergs. Apart from launch and recovery, all Swimmer operations are at 2 to 30 m (6.5 to 98 ft) above the seabed, and are remotely controlled by operators through a fast data link. The Swimmer AUV can navigate...
