Garmin Airmar 509LHW Thru-Hull Transducer, 3 kW, CHIRP Low 28-60 kHz, CHIRP High Wide 150-250 kHz, Temperature Sensor, Bare Wire

Overview

The Garmin 010-12187-20 is a 3 kW thru-hull CHIRP transducer (Airmar 509 LHW) that covers 28 to 60 kHz on the low band and 150 to 250 kHz on the high wide band, with depth and water temperature sensing. The low band is rated for depths up to 3,048 m (10,000 ft) and the high wide band is rated up to 152 m (500 ft), so you can keep a deep-water channel available while still getting a wide view in shallower water. It comes with a 15 m (49 ft) cable that terminates in bare wires, which is typical on high-power installs where wiring is routed directly to a sonar module or a dedicated harness.

This is the kind of transducer people put in larger sportfishers and commercial-style builds where clean bottom readings matter at speed and in rough water. The wide high-frequency beam helps keep fish and bait in view without having to run a tight, narrow cone, and the low-frequency side is there for canyon depth and deep structure work.

Key features

• Low/High Wide CHIRP coverage: 28 to 60 kHz low band plus 150 to 250 kHz high wide band.
• Depth performance: low band rated up to 3,048 m (10,000 ft); high wide band rated up to 152 m (500 ft).
• High wide beam stays at 25 degrees across the band for broad coverage in the upper water column.
• Low band beam narrows as frequency increases, from 23 degrees to 9 degrees port to starboard and from 11 degrees to 5 degrees fore to aft.
• Depth and fast-response water temperature sensing built in.
• Thru-hull external-mount style with urethane housing and fairing to keep the element in clean water flow.
• Supports hull deadrise angles up to 22 degrees.
• 15 m (49 ft) cable with bare-wire end for wiring into compatible sonar systems.

Installation and setup

This is a thru-hull installation, so plan for haul-out time and interior access to the mounting location. A 3 kW transducer also puts more load on the hull than smaller models, so professional installation is strongly recommended for correct hole prep, bedding, and alignment.

The fairing needs to be aligned so the transducer sits level in the water flow. On most boats that means placing it away from steps, strakes, and intakes that can introduce aerated water, and forward of prop wash so the sonar stays clean when you are on plane.

Compatibility and fit

Your sonar system must be able to drive a transducer rated up to 3 kW on the low band, and it must support Low/High Wide CHIRP operation across the stated frequency ranges. The cable terminates in bare wires, so confirm the correct wiring interface or adapter harness for your specific Garmin sonar module or chartplotter setup.

This model is commonly installed with Garmin sounder modules such as the GSD 25 or GSD 26 when a separate black box is used, especially in builds where longer cable runs and dedicated sonar power are part of the plan.

Use cases on board

For offshore runs, the 28 to 60 kHz low band is there for deep bottom tracking and marking structure, while the 150 to 250 kHz high wide band keeps coverage wide in water depths up to 152 m (500 ft). It is a good match for owners and captains who fish a mix of deep drops and shallower ledges and want one thru-hull to cover both without swapping transducers.

Maintenance and care

Keep the transducer face and fairing clean of growth to maintain consistent returns, especially if the boat lives in the water. During haul-outs, inspect the bedding and fasteners, and check the fairing for impact damage or movement.

Avoid aggressive scraping tools on the acoustic window, and do not aim a high-pressure washer directly at seals or cable exits.

What's included

• Thru-hull transducer with attached 15 m (49 ft) bare-wire cable
• Installation instructions

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