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Garmin

010-02930-02

GT17M-THF 20° Through-Hull CHIRP Mid-Frequency Sonde

The Garmin GT17M-THF 20-degree through-hull transducer is a robust stainless-steel solution, optimized for hulls with a deadrise angle of 17 to 24 degrees. It delivers stable and reliable CHIRP sonar performance, integrating galvanic isolation components for secure installation on metal hulls. This model is supplied with its galvanic isolation components.

Angle: 20 degrees

0 degree 12 degrees 20 degrees

Retail priceBenefit from the professional rate

£850.83 GBP

£850.83 GBP ~~£1,031.31 GBP~~

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In stock

Free pickup point from €150 in France
Pickup at Skysat possible

Custom installation

Trust Skysat to install the equipment on board

Request a quote

Installers near you

thanks to our network of approved installers

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Support service

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Technical specifications

Supported sonar technologies	CHIRP mid-band
Operating voltage	12
Fishfinder frequencies	CHIRP 150-240 kHz, CHIRP 40-75 kHz, 200 kHz, 50 kHz
Transducer material	Stainless steel
Compatible displays	Garmin chartplotters and fishfinders compatible
Wireless connectivity	None
Mounting type	Through the hull
CHIRP high frequency	150-240
CHIRP low frequency	40-75
Integrated speed sensor	No
Release year	2024.0
User level	Advanced

Detailed description

The Garmin GT17M-THF 20° through-hull transducer is designed to provide reliable and stable CHIRP sonar performance, specifically suited for vessels with a deadrise angle between 17 and 24 degrees. Made of stainless steel, this transducer ensures enhanced durability and broad compatibility with various hull materials, including fiberglass, wood, composites, aluminum, and steel.

Hull Material Installation and Compatibility

Installing the GT17M-THF transducer requires careful attention to the hull material. For aluminum or steel hulls, the use of the included galvanic isolation components is mandatory to prevent galvanic corrosion and water intrusion around the transducer. This requirement highlights Garmin's thoughtful design for secure and durable integration, unlike simpler transducers that may lack this essential protection on metal hulls. Installation is recommended by a qualified marine professional to ensure optimal performance and avoid damage.

Performance Optimization and Positioning

The GT17M-THF 20° model distinguishes itself from the 0° or 12° versions by its ability to precisely compensate for the specific deadrise angle, ensuring the transducer element is correctly oriented toward the bottom for maximum detection. For fiberglass hulls, a 98 mm hole is required, while metal hulls require a 101 mm hole. The transducer must be installed in a clean water area, free from turbulence created by propellers, keels, water intakes, or other equipment. Optimal positioning is critical: ahead of the engine for outboards, away from the propeller for inboards, or between engines for twin-engine setups. A software update for the Garmin chartplotter is required after installation to ensure compatibility and maximum performance. Regular maintenance with water-based antifouling paint and cleaning with non-aggressive solvents will extend the transducer's lifespan.

Documentation

Type	Nom
	Installation instructions - GT17M-THF transducer (20 degrees)

Expert opinion

Pol CONIN

Digital Manager

« Technical analysis of the Garmin GT17M-THF 20° through-hull transducer »

The Garmin GT17M-THF 20-degree transducer is a high-quality through-hull transducer solution for demanding marine applications. Its stainless steel construction provides superior robustness, essential for reliability in marine environments, particularly when compared to less impact- and wear-resistant plastic models. The inclusion of galvanic isolation components for metal hulls (aluminum, steel) is a major technical advantage, ensuring effective protection against corrosion and durable waterproofing—a critical feature often overlooked in less specialized equipment.

This model is specifically calibrated for deadrise angles of 17 to 24 degrees, making it a precise choice for hulls with this geometry. Installation must comply with Garmin guidelines, including the use of marine sealant and correct orientation (arrow pointing toward the keel). While installation requires hull drilling (98 mm for fiberglass, 101 mm for metal) and some expertise, the benefit in terms of undisturbed CHIRP sonar signal is significant compared to transom-mount transducers. Signal quality, crucial for identifying structures and fish, is directly linked to installation in a laminar flow area. The requirement for chartplotter software updates highlights the system integration of this transducer, ensuring compatibility and optimal performance within the Garmin ecosystem.

Compatibility: NMEA 2000, compatible with Garmin chartplotters (e.g., GPSMAP, ECHOMAP, echoMAP, and other Garmin Marine systems).

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GT17M-THF 20° Through-Hull CHIRP Mid-Frequency Sonde

£850.83 GBP

£850.83 GBP ~~£1,031.31 GBP~~

Frequently Asked Questions

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What is the Garmin GT17M-THF 20-degree through-hull transducer and what is it used for?

The Garmin GT17M-THF 20-degree through-hull transducer is a transducer designed to deliver reliable and stable CHIRP sonar performance. It is specifically suited for vessels with a deadrise angle between 17 and 24 degrees. Made of stainless steel, it ensures enhanced durability and is compatible with various hull materials.

With which hull materials is the Garmin GT17M-THF 20° transducer compatible?

The GT17M-THF 20° transducer is compatible with fiberglass, wood, composite, aluminum, and steel hulls. For aluminum or steel hulls, it is mandatory to use the included galvanic isolation components to prevent galvanic corrosion and water ingress around the transducer.

What is the ideal deadrise angle for installing the GT17M-THF transducer at 20 degrees?

For optimal performance, the GT17M-THF 20-degree transducer is designed for vessels with a deadrise angle between 17 and 24 degrees at the installation point. It is critical to precisely measure the deadrise angle at the chosen location before drilling holes in the hull.

Does the GT17M-THF 20-degree transducer require professional installation?

Yes, installation of the GT17M-THF 20-degree transducer by a qualified marine installer is strongly recommended to ensure optimal performance and avoid any risk of injury, damage to the device, or damage to the vessel. Incorrect installation can result in damage or injury.

What tools are required to install the Garmin GT17M-THF 20° transducer?

The main tools required for installation include:

A drill with a 3 mm (1/8 in) bitA hole saw of 98 mm (3 7/8 in) for fiberglass hulls or 101 mm (4 in) for metal hullsA 4.5 mm (3/16 in) Allen keyAn adjustable wrench suitable for nuts up to 108 mm (4 1/4 in)Marine sealant (flexible fast-curing type, for below the waterline)Sandpaper and masking tapeAdditional elements may be required depending on the hull type.

How to choose the best mounting location for the GT17M-THF 20-degree transducer on my boat?

For optimal performance, the transducer must be mounted in an area of clean, non-turbulent water. Consider the following:

On outboard and stern-drive boats, mount it forward and close to the engine(s).On inboard boats, mount it forward and away from the propeller and propeller shaft.Avoid mounting it behind frames, stiffeners, fittings, water intakes or discharges, or anything that could create air bubbles or turbulence.The transducer must be parallel to the fore-aft axis of your vessel.

Are special precautions required when installing the GT17M-THF 20° depth sounder on a metal hull?

Yes, when installing the GT17M-THF 20° depth sounder on an aluminum or steel hull, it is essential to use the included galvanic isolation components. Failure to install them could lead to galvanic corrosion and potential water ingress around the transducer. Ensure that the housing isolator is flush with the inner hull surface.

Do I need to update the software on my Garmin chartplotter after installing this sounder?

Yes, you must update the software on your Garmin chartplotter when installing the GT17M-THF 20-degree transducer. For update instructions, refer to your chartplotter’s user manual.