GT15M-THF 12° Through-Hull CHIRP Mid-Frequency Sonar

Yes, the Garmin GT15M-THF transducer is made of stainless steel and is compatible with a wide range of hull materials, including fiberglass, wood, composites, aluminum, and steel. It is important to note that for aluminum or steel hulls, the included galvanic isolation components must be installed to prevent corrosion.

The Garmin GT15M-THF transducer is made of stainless steel, providing robustness and versatility for installation on various hull types.

Yes, galvanic isolation components are included and must be installed when the Garmin GT15M-THF transducer is mounted on an aluminum or steel hull. This is essential to prevent galvanic corrosion and maintain hull integrity. Installation without these components on metal hulls could lead to water ingress around the transducer.

The hole diameter depends on your hull material:

For solid fiberglass or laminated fiberglass hulls, a 73 mm (2 7/8 in) hole is required.For metal hulls (aluminum or steel), a 75 mm (3 in) hole is needed.It is important to follow the specific installation instructions for hull preparation based on its material.

Yes, it is mandatory to update the software on your Garmin chartplotter when you install the GT15M-THF transducer. You can find the software update instructions in the owner’s manual of your chartplotter.

Cutting or splicing the transducer cable is generally not recommended. Unless specifically required to connect to a "black box" sonar requiring bare-wire connections, cutting the transducer cable may void your warranty. It is advised not to use the cable to lift or pull the transducer to prevent any damage.

To install the Garmin GT15M-THF transducer, you will need the following tools:

A drillA 3 mm (1/8 in) bitAn adjustable wrench suitable for nuts up to 75 mm (3 in)Marine sealant (flexible, fast-curing type for below the waterline)Mild household detergent or rubbing alcoholSandpaperMasking tapeWaterproof electrical insulating tapeGrommets (optional)Antifouling paint (water-based) (optional)

For fiberglass hulls: a 73 mm (2 7/8 in) hole saw and marine epoxy resin (for laminated fiberglass hulls). For metal hulls: a file and a 75 mm (3 in) hole saw are required.

When preparing a fiberglass sandwich hull, it is critical to seal the core to prevent water intrusion. Follow these steps:

Drill a 3 mm (1/8 in) pilot hole from the outside.Apply masking tape around the hole on the outside to reduce gelcoat cracking.Use a 73 mm (2 7/8 in) hole saw to drill the transducer hole through the hull from the outside.From the inside, use a slightly larger hole saw to cut only the inner fiberglass skin and core, ensuring the outer skin remains intact.Seal the exposed core inside the hull using fiberglass and epoxy resin or casting epoxy resin, following the specific instructions for each method to create a watertight joint and restore the correct hole diameter.

The hole size depends on your hull material:

For a solid or laminated fiberglass hull, you need to drill a 73 mm (2 7/8 in) hole.

For a metal hull (aluminum or steel), you need to drill a 75 mm (3 in) hole.

For optimal performance, the transducer must be mounted in an area of clean, non-turbulent water. Here are some general guidelines:

On outboard and sterndrive powerboats, install the transducer in front of and close to the engine(s). On inboard powerboats, mount it in front of and away from the propeller and propeller shaft. On stepped hulls, install it in front of the first step. Avoid mounting it behind strakes, reinforcements, fittings, water intakes or discharges, or anything that could create air bubbles or turbulence. The transducer must be parallel to the boat's fore-aft axis and must not be mounted where it could be struck during launching, trailering, or storage.

To ensure correct orientation and optimal alignment of the sonar beam with your boat’s deadrise angle, once the transducer is inserted into the mounting hole and before fully tightening the hull nut, you must rotate it. The arrow on top of the transducer must point toward the keel of the boat. This orientation is critical for the transducer’s internal angle to align properly with your vessel’s deadrise angle.

Yes, to achieve the best possible performance and to avoid potential damage to the device or your boat, installation by a qualified marine installer is strongly recommended. Incorrect installation can result in injury, damage, or suboptimal performance of the transducer.

The Garmin GT15M-THF transducer is made of stainless steel, making it compatible with a wide range of hull materials. It can be installed on boats with fiberglass, wood, composite, aluminum, or steel hulls.

It is important to note that when installing on an aluminum or steel hull, you must absolutely install the included galvanic isolation components to prevent corrosion.

Deadrise angle is the measure of the angle between a horizontal line and the outer hull at a given point. For optimal sonar performance, it is crucial that the angle of the transducer you purchase matches as closely as possible the deadrise angle at the installation location.

The Garmin GT15M-THF transducer is a 12-degree model, specifically designed for deadrise angles ranging from 6 to 16 degrees. It is recommended to check the deadrise angle of your hull at the chosen location before drilling.

Yes, the Garmin GT15M-THF transducer can be installed on aluminum or steel hulls. It is made of stainless steel, which is designed for this compatibility.

However, it is imperative to install the included galvanic isolation components when installing on an aluminum or steel hull. Failure to do so would result in galvanic corrosion, which could cause water ingress around the transducer.

The Garmin GT15M-THF transducer is designed for seamless integration with Garmin chartplotter and fishfinder systems. To ensure compatibility and optimal performance, it is necessary to update your Garmin chartplotter software when installing this device. You can find the update instructions in your chartplotter's user manual.

The Garmin GT15M-THF transducer is made of stainless steel. This robust material provides high durability and broad compatibility with various hull types, including metal hulls.

To ensure the longevity and proper operation of your transducer, follow these precautions:

Operation: Always use the transducer when it is submerged in water. Operating it in air can cause heat damage.

Cleaning: Never use solvents such as white spirit, acetone, methyl ethyl ketone (MEK), or similar products, as they can permanently damage the transducer surface. Do not use electric sanders, high-pressure cleaners, or abrasive tools.

Handling: Never lift or pull the transducer by its cable to avoid damaging the cable and the transducer itself.

Additional note: If the transducer is removed from the water for cleaning, ensure it is completely dry before reinstallation.

Unless you are connecting the transducer to a sonar head that requires bare-wire connections, you must not cut or splice the transducer cable. Cutting the transducer cable, outside of what is required for a bare-wire connection to a sonar head, may void your warranty.

The main differences between the GT15M-THF and GT12M-THF models lie in their construction material and compatibility with hull materials:

The GT15M-THF is made of stainless steel and is compatible with fiberglass, wood, composite, aluminum, and steel hulls. It includes galvanic isolation components for metal hulls.The GT12M-THF is made of brass and is only compatible with fiberglass, wood, or composite hulls. It must not be installed on aluminum or steel hulls, as this would cause galvanic corrosion.Both models share a 12-degree angle, suitable for deadrise angles between 6 and 16 degrees.