GARMIN GT15M-IH Transducer Instruction Manual

: June 4, 2024
: Garmin

Table of Contents

Mounting Considerations
Installing the In-Hull Tank and Transducer
Software Update
Updating the Device Software
Documents / Resources

GT15M-IH Transducer Installation Instructions

Mounting Considerations

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.
TIP: You can search the Internet for marine electronics forums and videos that can help you to select the best mounting location.

Tools Needed

1 Phillips screwdriver
220 grit sandpaper
marine grade adhesive
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°.

Testing the Mounting Location
Before you permanently mount the transducer, you should test the transducer feedback at your mounting location with the boat in the water.

Place the transducer inside a thin plastic bag.
Fill the bag with enough water to cover the bottom of the transducer, and secure the bag with a zip tie.
Wet the surface of the hull.
Place the bagged transducer on the mounting location.
Observe the feedback of the transducer on your Chartplotter or fishfinder.
If the transducer does not function as expected, select a new mounting location and repeat steps 3 through 5.

Installing the In-Hull Tank and Transducer

Before you install the in-hull tank and transducer, you must figure out the deadrise angle (Deadrise Angle, page 1), and select the tank that provides the most-level installation of the transducer.

Sand the tested mounting location (Testing the Mounting Location, page 1) with 220-grit sandpaper.
Clean the tested mounting location with alcohol.
Apply marine-grade adhesive À to the bottom of the tank.
Place the tank in the boat hull at the top of the tank level with the water line, and with the arrow Á pointing to the boat keel.
When the adhesive is dry, insert the O-ring Â in the groove of the tank.
Fill the tank with RV/marine antifreeze fluid or mineral oil.
Insert the transducer into the tank, aligning the arrow on the transducer and the notch on the tank Ã
Using the enclosed screws secure the transducer Ä to the tank.
NOTE: Do not overtighten the screws.
Route the cable and connect the transducer to your Chartplotter or fishfinder.

Software Update

You may need to update the device software when you install the device or add an accessory to the device.
Loading the New Software on a Memory Card
You must copy the software update to a memory card using a computer that is running Windows ® software.
NOTE: You can contact Garmin ® customer support to order a preloaded software update card if you do not have a computer with Windows software.

Insert a memory card into the card slot on the computer.
Go to www.garmin.com/support/software/marine.html.
Select Download next to the software bundle that corresponds with your device.
Read and agree to the terms.
Select Download.
If necessary, select Run.
If necessary, select the drive associated with the memory card, and select Next > Finish.

Updating the Device Software

Before you can update the software, you must obtain a software-update memory card or load the latest software onto a memory card.

Turn on the Chartplotter.
After the home screen appears, insert the memory card into the card slot.
NOTE: In order for the software update instructions to appear, the device must be fully booted before the card is inserted.
Follow the on-screen instructions.
Wait several minutes while the software update process completes.
When prompted, leave the memory card in place and restart the Chartplotter manually.
Remove the memory card.
NOTE: If the memory card is removed before the device restarts fully, the software update is not complete. Garmin ® and the Garmin logo are trademarks of Garmin Ltd. or its subsidiaries, registered in the USA and other countries. These trademarks may not be used without the express permission of Garmin.

Garmin and the Garmin logo are trademarks of Garmin Ltd. or its subsidiaries, registered in the USA and other countries. These trademarks may not be used without the express permission of Garmin.

© 2015 Garmin Ltd. or its subsidiaries
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