Garmin GT15M-IH Installation Instructions

Mounting Considerations

• The transducer should be mounted over solid fiberglass hulls only, up to 16 mm (
• On single thickness fiberglass hulls, the transducer should be mounted in the bilge area near the keel and
transom.
• The transducer should not be mounted aft of the water pickup and other protrusions.
• The transducer should not be mounted over a strake.
• The transducer should be mounted over solid fiberglass, with no dead air space or coring in the boat hull.
• The transducer should be mounted as flat as possible in the boat hull.
• You can refer to the Transducer Placement Guide at
about transducer placement.

Tools Needed

• #1 Phillips screwdriver
• 220-grit sandpaper
• Marine-grade adhesive suitable for the mounting location material
• RV/marine antifreeze fluid or mineral oil
• Rubbing alcohol

Deadrise Angle

Deadrise is the angle formed between a horizontal line and a boat hull at a single point. You can measure the
deadrise angle with a smartphone application, an angle finder, a protractor, or a digital level. You can also ask
your boat manufacturer for the deadrise angle of the specific point on your boat hull.
NOTE: A boat may have several deadrise angles depending on the shape of the hull. Measure the deadrise angle
only at the location where you plan to install the transducer.

In-Hull Tank Considerations

• On a boat hull with a deadrise angle between 0 and 3 degrees, you must install the tank labeled 0°.
• On a boat hull with a deadrise angle between 4 and 8 degrees, you must install the tank labeled 5°.
• On a boat hull with a deadrise angle between 9 and 16 degrees, you must install the tank labeled 12°.
• On a boat hull with a deadrise angle between 17 and 25 degrees, you must install the tank labeled 20°.
December 2023
GT15M-IH
INSTALLATION INSTRUCTIONS
garmin.com/manuals/gt15mih
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