GT23M-TH Transom-Mount Stainless Steel CHIRP/ClearVü Sonde

The Garmin GT23M-TH is a stainless steel through-hull transducer. It integrates two advanced sonar technologies:

Traditional CHIRP in mid-band: Operates on a frequency range of 80-160 kHz with 600 W power. CHIRP ClearVü: Operates on frequencies 260/455 kHz with 500 W power. It also enables precise monitoring of depth and water temperature.

The GT23M-TH transducer delivers 600 W for traditional CHIRP sonar in the mid-band (80–160 kHz) and 500 W for CHIRP ClearVü sonar (260/455 kHz).

The Garmin GT23M-TH sounder can reach a maximum depth of 549 meters using traditional CHIRP mode. In CHIRP ClearVü mode, the maximum depth is 305 meters.

The Garmin GT23M-TH transducer uses an 8-pin connector to connect to a compatible Garmin device.

The GT23M-TH transducer is made of stainless steel. This material is selected for its robustness and corrosion resistance, making it particularly suitable for demanding marine environments and ensuring a long service life.

The beam widths for the GT23M-TH transducer are as follows:

For traditional CHIRP sonar: 24°/13°. For CHIRP ClearVü sonar: 2.0°x51° at 260 kHz and 1.4°x29° at 455 kHz.

Yes, the Garmin GT23M-TH transducer can measure and provide water temperature data in addition to depth.

The GT23M-TH transducer is designed for inshore and offshore anglers. Its through-hull mounting is compatible with fiberglass hulls (whether cored or not) and metal hulls.

Yes, it is necessary to update the software on your Garmin chartplotter when installing this depth sounder to ensure optimal compatibility and access to all features and best performance.

The Garmin GT23M-TH transducer is designed for thru-hull installation, meaning it is mounted by drilling through the boat's hull from the outside to the inside.

For the installation of the GT23M-TH transducer, you will need the following tools:

Drill and bits (3 mm, 9 mm, 13 mm)Open-end or adjustable wrenches (13 mm and up to 38 mm)Marine sealant (flexible, fast-curing, for below the waterline)Mild detergent or rubbing alcoholSandpaper and masking tapeWaterproof electrical tapeHole saw (25 mm or 32 mm depending on hull type)For fiberglass hulls with core: marine epoxy resin.If using a fairing block: jigsaw or table saw, rasp.

A fairing block is required if the deadrise angle of your hull at the mounting point exceeds 5°. It positions the transducer parallel to the waterline, which is critical for accurate sonar performance and optimal operation.

The fairing block supplied with the GT23M-TH transducer can compensate for a leeway angle of up to 25°. This ensures optimal sonar beam orientation, even on hulls with a pronounced angle.

For optimal performance, the depth sounder must be installed in an area of clean, non-turbulent water. Here are some general considerations:

Outboard and sterndrive boats: Mount the depth sounder in front of and near the engine(s).Inboard boats: Mount the depth sounder in front of and away from the propeller and propeller shaft.Powerboats with stepped hulls: Mount the depth sounder in front of the first step.General positioning: The depth sounder must be mounted parallel to the boat's fore-aft axis and avoid turbulence zones created by strakes, appendages, water intakes or discharges.

Yes, it is mandatory to install the transducer with one or more anti-rotation bolts (included). Failure to do so may cause the device to rotate when the boat is underway, potentially damaging your vessel.

For a fiberglass hull with core, preparation is critical to prevent water intrusion. After drilling holes for the rod and anti-rotation bolts, the exposed core must be carefully cut away and sealed with high-quality marine epoxy resin. Allow the resin to cure completely before mounting the transducer in the hull.

Yes, it is essential to apply marine sealant. You must apply it around the base of the transducer’s shaft and the anti-rotation bolts. If a fairing block is used, sealant must also be applied to the side of the block in contact with the hull and to the side of the internal reinforcement block.

If you need to print the mounting template, it is crucial to ensure the scale is set to 100% in your printing software settings (for example, select "Actual Size" in Adobe Acrobat). After printing, use a ruler to measure at least one dimension line on the template to verify it is at the correct scale. However, it is recommended to use the template provided in the product box.

When drilling or cutting into the hull, several precautions must be taken:

Always check what is on the other side of the surface to avoid damaging the vessel or its equipment.Apply masking tape to the drilling area to help reduce cracks in the gelcoat.Always wear safety goggles, hearing protection, and a dust mask to prevent injury.

Yes, this equipment should be installed by a qualified marine installer. This ensures correct installation, optimal performance of the transducer, and helps prevent potential damage to the boat or the transducer.