Unmanned Surface Vehicles (USVs) have been proposed for use in several mission-critical operations in recent years. Although many autonomous behaviors have been developed by the research community, USV systems are greatly limited in functionality due to imperfect perception information and uncertainties in platform control. This paper presents a practical approach in considering these issues during the creation of autonomous behaviors. The approach allows autonomous behaviors to consider imperfect perception information and uncertainties in control during planning, and has been demonstrated successfully on a 9 meter USV.