"Fish finder" and "sounder" are used interchangeably in Australia, but choosing the right unit comes down to four things: screen size, sonar technology, transducer and charts. Here's what actually matters.
Sonar technology
- Traditional CHIRP sonar — reliable depth, bottom structure and fish arches. Every sounder has it; the quality varies with power and frequency.
- DownScan / ClearVü / DownVision — photo-like detail directly under the boat. Brilliant for structure and bait schools.
- SideScan / SideVü / SideScan — coverage to both sides of the boat. The single biggest upgrade for finding fish fast in estuaries and dams.
- Live sonar (LiveScope / ActiveTarget) — real-time video-like view of fish reacting to your lure. A game changer for tournament anglers.
Screen size and mounting
A 7" unit is the sweet spot for most tinnies and kayaks; 9" is ideal for split-screen chart + sonar on bigger boats; 12"+ suits offshore consoles where you run sonar, chart and radar together.
Transducers
The transducer is half the system. Through-hull and transom mounts suit different hulls, and the scanning modes you want must be supported by both the head unit and the transducer — check compatibility before buying a combo.
Charts
Garmin units ship with Garmin Navionics+ mapping, Lowrance and Simrad include C-MAP, Humminbird uses Lakemaster or CoastMaster. If you fish new areas constantly, chart quality is worth prioritising.
Still unsure? Send us your boat and budget in the chat — we'll spec the exact unit and transducer for your hull.
