Abstract: Techniques are disclosed for systems and methods to provide accurate and reliable compact sonar systems for mobile structures. A modular sonar system includes one or more sonar transducer assemblies and at least two transducer modules disposed substantially within the sonar transducer assemblies. Each transducer module includes a transducer element and a module frame. The module frame is configured to support the transducer element, to physically couple to other transducer modules, and/or to physically couple to a sonar transducer assembly to secure the transducer module. The system may additionally include an actuator configured to adjust an orientation of the transducer module. Resulting sonar data and/or imagery may be displayed to a user and/or used to adjust a steering actuator, a propulsion system thrust, and/or other operational systems of the mobile structure.