Open ocean surfing for increased range and endurance

This paper presents an evaluation of ocean wave surfing to reduce support requirements for unmanned marine vehicles. Small marine vehicles are at a significant cost disadvantage when compared with larger manned vehicles because of their limited range and endurance. Since the total cost of ownership includes deck space and labor, small vehicles with daily refueling cycles are nearly as expensive to operate as larger manned vehicles. This paper presents the minimum criteria for effective ocean surfing in a variety of sea conditions. The essential technologies are a high lift-to-drag hull form, a high efficiency propulsor, a local-sea sensing inertial navigation system, and adaptive surfing control strategies. Range and endurance figures are estimated using an out-and-back mission profile in a variety of standard sea conditions. Preliminary results indicate that ocean-crossing range at five to ten knots is possible with favorable sea conditions, and unrefueled endurance is increased from days to weeks or months.