Overview

The Garmin 010-12402-20 is a GT15M-TH thru-hull transducer with an 8-pin connector for mid-band CHIRP traditional sonar (85-165 kHz). It runs at 600 W with a listed beamwidth of 24° to 13°, includes a 20 ft (6.1 m) cable, and reads water temperature.

This is the style of transducer you install through the hull below the waterline so the element sits in clean water and keeps a consistent bottom picture when you are running or dealing with chop. Maximum depth is listed up to 1,900 ft (579 m) in freshwater, with real-world results depending on hull, mounting location, and water conditions.

Key features

• Mid-band CHIRP traditional sonar: 85-165 kHz at 600 W.
• Thru-hull mounting for a stable bottom reading when a transom location gets aerated.
• Bronze thru-hull housing and stem for below-the-waterline installation.
• Listed maximum depth up to 1,900 ft (579 m) in freshwater conditions.
• Beamwidth 24° to 13° for a mix of coverage and target separation.
• Built-in temperature sensing for water temp at the display.
• 8-pin connector with a 20 ft (6.1 m) cable for compatible Garmin sonar ports/adapters.

Installation and setup

Plan for a true thru-hull install: drill the hull, bed the stem with marine sealant, and lock the transducer in place using the included anti-rotation hardware so it cannot spin while underway. If your hull is cored fiberglass, the core around the hole should be sealed so water cannot wick into the laminate.

The supported deadrise range is listed as 0° to 6°. On hulls with more angle, a fairing block is typically required to keep the element aimed correctly and to seat the hardware properly against the hull surface.

Compatibility and fit

This model uses an 8-pin transducer connection and is intended for systems that accept Garmin 8-pin sonar inputs (or the correct adapter where applicable). Confirm connector style and sonar support on your display or black box before drilling the hull.

Installation instructions cover cored fiberglass, non-cored fiberglass, wood, and metal hulls. Placement matters for clean water flow, so it is worth checking inside access for the backing nut and hardware before choosing the final spot.

What’s included

• GT15M-TH transducer
• Thru-hull mount
• Mounting hardware
• Documentation

On-board use

This is a solid match for boats that spend time fishing structure and want CHIRP traditional sonar with a thru-hull install instead of a transom mount. It also makes sense when you want water temperature at the helm without adding a separate temp sensor.