Humminbird Piranhamax 4PiranhaMAX 4, most affordable Humminbird sonar for small boats. Humminbird PiranhaMAX 4 The Humminbird PiranhaMAX 4 is Humminbird's most affordable sonar, basic down beam sonar with 4. 3" color display. For small boats, jon boats, kayaks, or anyone who just wants to see fish without spending much. Key Features 4. 3" Color Display Down Beam Sonar Bottom Tracking and Fish ID Standalone Unit Easy Installation Most Affordable Humminbird Sonar Why Choose