The US Navy requires unmanned Surface Vessels (USVs) and combatants which are affordable, reliable, fuel efficient, and proven hull forms. Procuring commercially available hull designs provide a cost effective means of achieve this. However, commercially available platforms are typically not designed for fuel efficient operations over broad operational speed ranges required for military vessels; i.e., lower transit speed, endurance range speed, and higher sustained sprint speed. The speed time profile for a USV will vary highly between peace time and war time operations, making broad range fuel efficiency more critical. Existing passive Hydrodynamic Hull Appendages (HHA) have demonstrated the ability to reduce hull resistance and vertical accelerations, and thereby, improve fuel efficiency and vessel motions. The benefits of passive HHA are optimized for the operating speed of the vessel and not to provide a consistent benefit across a broad range of Froude numbers (0.15 0.75). A reliable, wide-range HHA is required to enable commercially available hull designs to provide affordable, reliable, fuel-efficient capability. To achieve this the HHA will have to be actively controlled to optimize efficiency across a large speed range. Development of a reliable, wide-range HHA will better enable a modified Commercial Off the Shelf (COTS) hull-form to meet USV and combatant operational requirements, improving the autonomous systems endurance, persistence, and reliability. The development targets hulls 150-400 in length. Innovation is required to develop an advanced HHA that provides fuel savings across a wide range of Froude numbers and provides reliable operation with minimal maintenance. Additionally, the HHA must be readily integrated into an existing hull form, such that it does not require significant modification of existing commercial hull forms. The advanced HHA will target a minimum 5-10% fuel efficiency benefit across a wide operational speed range and shall target a total acquisition and integration cost of less than $750K per unit to provide a Return On Investment (ROI) within 1-2 years. The number of units required is dependent on how broadly the technology can be applied; for planning purposes ~10-20 units would be required over a 10-year period. The advanced HHAs performance will be assessed against the power delivered ratio for a hull form without an HHA as compared to a hull form with an HHA. The HHA shall be designed for (a) a 25-year service life, (b) fail safe operation, (c) 80% reliability, and (d) preventative maintenance requirements of no more than once per year. A reliability assessment shall be completed to assess the whole systems reliability, broken down by subsystems and components, to validate improvements relative to current systems.
