Garmin GT12M-THF Bronze Thru-Hull Transducer, 350W, Mid-Band CHIRP 85-165 kHz, 8-Pin, Depth/Temp

Overview

The Garmin GT12M is a bronze thru-hull transducer built for mid-band CHIRP sonar at 350 W, with an operating range of 85 to 165 kHz. It is meant to be installed flush to the hull to keep drag down while still giving clean bottom definition and clear target separation on a compatible display.

This transducer family is offered in tilt options so the beam can point closer to straight down on hulls with different deadrise. Maximum depth performance is rated up to 800 ft in saltwater and 1,200 ft in freshwater, depending on conditions and installation.

Key features

• 350 W mid-band CHIRP sonar (85 to 165 kHz) for a wide coverage area and clear returns
• Flush thru-hull housing in bronze for a clean exterior profile
• Tilt versions available to match common hull deadrise angles (0°, 12°, 20°)
• Beamwidth rated 16° to 24°
• 50 ft cable with an 8-pin connection for compatible Garmin sounders and chartplotters
• Reports depth and water temperature
• Auto-identification support with compatible Garmin systems for quicker setup

Variants

This transducer is offered in multiple configurations based on built-in tilt angle.

The tilt angle changes how the transducer element is set in the housing, helping keep the sonar beam aimed closer to vertical once the unit is installed through the hull.

• 010-02867-00: Tilt 0°. Typically used where the mounting area is close to flat and the hull deadrise is low (about 0° to 7°).
• 010-02867-01: Tilt 12°. Suited to moderate deadrise installations (about 8° to 15°) to help keep the beam aimed down.
• 010-02867-02: Tilt 20°. Intended for higher deadrise mounting locations (about 16° to 24°) without relying on a fairing block for angle correction.

Compatibility and fit

This is a thru-hull style transducer, so hull access and interior clearance matter as much as exterior placement. It connects via an 8-pin plug and is meant for compatible Garmin sonar systems that support CHIRP operation.

For best readings, mount it in solid water flow, forward of strakes and through-hull fittings when possible, and away from spots that aerate at speed. The tilt option should match the deadrise at the exact mounting location, not the boat’s advertised deadrise at the transom.

Installation and setup

Thru-hull installs are permanent and benefit from careful planning: choose a location you can reach to tighten the hardware and route the 50 ft cable without tight bends. A flush exterior profile helps reduce turbulence around the face of the transducer.

On compatible Garmin units, auto-identification can simplify initial configuration. After installation, verify the transducer is reading depth and temperature correctly at idle before relying on it at speed.

Materials and corrosion notes

The housing is bronze, a common choice for thru-hull hardware in saltwater. On metal hulls, follow standard isolation practices and bonding guidance for your vessel to manage galvanic interaction between dissimilar metals.

What’s included

• GT12M-THF transducer
• Jam nut
• Washer
• Documentation

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