Garmin GT21-TM Transom Mount Transducer, Traditional 600W, 50/200kHz, ClearVü CHIRP 500W, 260 & 455kHz

The Garmin GT21-TM Transom Mount Transducer is purpose-built for serious anglers and boaters who demand dual-technology sonar on the water. This transom-mounted unit combines traditional 50/200kHz sonar with ClearVü CHIRP technology—delivering the coverage and clarity needed for both deep offshore structure and shallow coastal flats. Whether you're targeting stripers in a river system or hunting grouper on the shelf, the GT21-TM gives you the diagnostic power to locate fish and structure with confidence, eliminating guesswork from your fishing decisions.

This transducer operates on dual frequency bands: a traditional 600-watt output at 50/200kHz for broad-range depth sensing and target discrimination, paired with a 500-watt ClearVü CHIRP sonar system at 260 and 455kHz for ultra-high-resolution, forward-looking scanning. The CHIRP (Compressed High-Intensity Radar Pulse) technology transmits a continuous sweep of frequencies rather than a single tone, producing photographic-quality images of bottom composition, suspended structure, and fish holding patterns. The transom-mount design positions the transducer flush against your hull's exterior, minimizing drag while maintaining direct water contact for unobstructed signal transmission—critical for accurate readings at speed or in rough conditions.

The GT21-TM excels on center console boats, bay boats, and offshore fishermen who need both traditional sonar depth and structure mapping alongside advanced CHIRP imaging. Installation requires connection to a compatible Garmin chartplotter or marine display unit; verify transducer cable routing and display compatibility before purchase. At 2.8 pounds with compact dimensions of 6 x 5 x 12 inches, it's designed for clean mounting on transom brackets without added weight penalty. This transducer is ideal for anglers who fish variable depths—from shallow backwater creeks to blue water—where frequency flexibility and dual-technology redundancy translate directly to catch success.