The Double Eagle Concept uses a modular approach to provide flexible systems for MCM applications (Mine Hunting, Mine Disposal). It is aimed at providing a hydro dynamically stable, highly reliable system with exceptional performance and low life cycle cost.
The design of Double Eagle was from day one targeted on modular design and open architecture with the possibility to replace main system elements. This allows upgrades and reconfiguration, enabling use of new technology and changes in naval tactics/strategy as part of an evolutionary strategy. This has lead to a system where core functionality and core subsystems have been reused in several products and configurations, all to provide system with extreme stability yet still highly manoeuvrable.
The SAROV package gives Double Eagle autonomous capability and still retains all the features of the basic system. It consists of fairing components, a battery pack, modules for communication and navigation and a docking unit. The SAROV package requires factory modification of the ROV.
SAROV package enhances the capabilities of the Double Eagle family of ROVs. It adds autonomous operation and underwater docking to the capabilities of the existing systems. It allows the ROV to be operated both with and without a tether cable. This increases the range and versatility of the Double Eagle ROVs. It extends their capabilities for mine hunting and maritime security operations into difficult areas such as shallow waters and harbours. It also enables the ROVs to be used from remote platforms and multi vehicle operations. Of course the Double Eagle is available in a SAROV configuration direct from the factory when originally delivered.
The SAROV Offshore Hybrid has a similar length to its military counterpart, it is available in two configurations:
single and double hull rated to 3000m water depth. Both are 3m in length and 450mm in height, however, the double hull increases the Offshore Hybrid’s width from 400mm to 900mm and the launch weight from 250kg to 650kg.
The double hull increases the forward speed from 4kts to 5kts and the forward thrust from 30kgf to 100kgf (although the lateral thrust is marginally increased from 25kgf to 30kgf and the vertical thrust remains the same at 50kgf). This thrust may be a bit low for certain applications, but since the control system allows alternate thruster configurations, tool packs can include additional thrusters if needed without having to sacrifice size, weight and endurance for other missions. It also doubles the payload from 40kg to 80kg and increases the battery capacity from 8kWh to 14kWh which manifests as an increase from 2–4 hours to 3–10 hours.
“When in ROV mode, the vehicle is connected to the surface facilities by an umbilical,” said Jan Siesjo, chief engineer at Saab Underwater Systems. “In the military versions, with their characteristic shallower water depths and shorter ranges the umbilical commonly provides both control and power.
“The SAROV Offshore Hybrid, however, contains its own power supply in the form of a bank of batteries located within the vehicle. This means that the umbilical can be reduced to a simple fibre optic line for communication (for control/data) only. This fibre optic tether is so light, that it obviates any clashing problems when looking at risers and mooring systems in FPSOs that might be expected in more traditional vehicles.”
Various autonomous vehicles are commonly used in the offshore sector to carry out pipeline or grid pattern surveys. For these, being able to ‘fly’ at speed is an advantage, and they consequently feature a smooth hydrodynamic morphology with thrusters positioned at the stern.