Basics of Garmin Transducer Installation

Electromagnetic interference (EMI) may distort sonar information and images. Placing a transducer or routing the transducer cable near a source of EMI may degrade sonar information. Sources include but are not limited to: 

• Bilge pumps

• Magnets 

• AC/DC power cables 

• Batteries

• Trolling motors

• Electrically charged devices and equipment

Transom mounted transducers are attached to the back of the transom of a vessel. Trailered vessels typically use this mounting style. A transom-mounted installation usually gives good readings up to 25-30 mph depending on installation. Transom-mounted transducers are not compatible with jet propulsion vessels. The jet exhaust creates a vast amount of water turbulence that may result in degrading the sonar signal so that it cannot effectively move through the water column to get a good sonar return. If the boat is a jet propulsion vessel, utilize the techniques found in the "In Hull" or "Through Hull" installation procedures.

• Choose a location where the water flow is the smoothest, and minimum turbulence and bubbles will exist, especially at high speed

• The transducer requires continuous contact in water, and the sounder beam is unobstructed by the keel or propeller shaft

• Make sure that there is adequate headroom and there is a minimum deadrise angle

• Look for features on the hull like lifting strakes or keels. These structures will cause cavitation and will negatively affect performance. A disadvantage of a transom mount is that air bubbles will affect the sonar performance

• The location should be as close to the center of the boat and on the side prop wash. On most engines, this will be on the starboard (right) side

• On boats with outboard or inboard/outboard motors, the location should be at least 15 inches (38 cm) away from the propeller

• The location should not be in the path of the propeller on single-drive boats. The transducer can cause cavitation that degrades the boat's performance and could damage the propeller

• The location should not be downstream of any strakes, struts, fittings, water intake or discharge ports, or anything that creates air bubbles or causes the water to become turbulent

• The location should be between the drives on twin-drive boats, if possible, and only if the propellers swing in a rotation that causes the downswing of the propellers to cause the cavitation to hit the back of the transducer instead of the face

• Avoid locations where physical jarring of the transducer could occur. Consider the position of the transducer when launching, hauling, or storing

• The transducer should be oriented so that it is parallel with the waterline

•  Transom-mounted transducers are not compatible with jet propulsion or drive vessels. The jet exhaust creates a vast amount of water turbulence that may result in degrading the sonar signal so that it cannot effectively move through the water column to get a good sonar return. If the boat is jet propulsion or drive vessel, utilize the techniques found in the "In Hull" or "Through Hull" installation procedures

NOTE: Step Mounting a transducer follows the same steps as the Transom transducers do. The difference is that the transducer will mount on the step instead of the transom.

When installing a transom-mounted transducer, it is crucial to carefully follow the installation instructions provided within each transducer kit. The following are basic guidelines to consider when mounting this type of transducer:

Below is an image of a sample installation and doesn’t apply to every boat.

Speed Sensor

The speed sensor’s installation is not as critical as the depth transducer installation. The guidelines will be like those above, but there are other considerations:

• Take care to avoid mounting it too close to a transom-mounted depth transducer, as it can potentially cause cavitation that will degrade sonar performance

• If there is adequate room, it’s advisable to mount the speed sensor on the port (left) side of the engine propeller

Below is an image of a sample installation and doesn’t apply to every boat.

Closely following the packaged manuals and the tips outlined above will have the best opportunity to have an easy installation and optimal performance from the transducer.

An in-hull transducer installation is bonded to the inside of the hull with epoxy and will typically consist of a container filled with propylene glycol. When installing an in-hull mounted transducer, it is essential to carefully follow the installation instructions provided within each transducer kit. The following are basic guidelines to consider when mounting this type of transducer:

In-Hull Pros and Cons

• No need to drill through the vessel; no drag

• Trailering the boat without causing damage to the transducer

• Can be installed and serviced with the ship in the water

• Excellent high-speed performance if water flow below the sensor is free-flowing (no turbulence)

• Works with any engine type: inboard, outboard, and I/O when installed over solid fiberglass

• Performs well on both power and sailboats

• Not recommended for metal, wood or cored fiberglass hulls

• Loss of signal by transmitting through-hull

Placement of the In-hull transducer

• Close to the centerline

• The signal will pass through up to 0.75” thickness

  • The GT8HW-IH transducer is rated at 250W so the hull thickness cannot be greater than .50" thickness

• Avoid mounting too close to the keel; cone signal shape is approximately 22 degrees. If too close to the keel, it can pick up an echo

• Should be in the aft of the boat

• Do not mount the transducer behind strakes, struts, fittings, water intake or discharge ports, or anything that creates air bubbles or causes the water to become turbulent

• The vessels hull that is directly underneath the transducer must be in constant contact with the water

• The transducer must be in clean, flowing water (non-turbulent) water for optimal performance

• Test the location - use a thin plastic bag filled with water, place the transducer inside the bag, and close with a zip tie.  Use water to wet the desired hull location. Plugin transducer and check the chartplotter’s sonar page for good returns

• Periodically check the tank and fill when needed with propylene glycol. Flashing depth or no depth information indicates that there is not enough fluid or no fluid in the reservoir

Thru-hull transducers are just that; a hole through the hull of the boat with the transducer installed through the hole. Thru-hull transducers come in two versions, tilted element or with a fairing block. Garmin also has SideVu transducers. If the hull has a deadrise of more than 5 degrees, a pair of thru-hulls will be required.

There are specific placement locations based on the type of hull and type of engine on the vessel be sure to read through the manufacturers mounting considerations before drilling a hole.

Below are some general guidelines for placement.  Because of the complexity of thru-hull installations, Garmin does recommend a professional installer for this type of transducer installation.

• Outboard and Sterndrive Vessels: the transducer should be mounted in front of and close to the engine or engines

• Inboard Vessels: the transducer should be mounted in front of and far away from the engine propeller and shaft

• Step-hull Vessels: the transducer should be mounted in front of the first step

• Full-Keel Vessels: the transducer should be mounted at a slight angle that aims at the bow, not parallel to the centerline

• Fin-Keel Vessels: the transducer should be mounted 10 – 30 inches (25 cm – 75cm) in front of the keel and a maximum of 4 inches (10 cm) to the side of the centerline

• Displacement Hulls: the transducer should be mounted approximately 1/3 aft of the waterline length of the vessel from the bow, and 6 – 12 inches (150 – 300 mm) to the side of the centerline

• The transducer mounted parallel to the bow-stern axis of the vessel

• Do not mount the transducer behind strakes, struts, fittings, water intake or discharge ports, or anything that creates air bubbles or causes the water to become turbulent

• The transducer must be in clean, flowing water (non-turbulent) water for optimal performance

• The transducer location should not cause jarring when launching, hauling, or storing

• Single-Drive vessels: the transducer must not be mounted in the path of the propeller. The transducer can cause cavitation that can degrade the performance of the boat and damage the propeller

• Twin-Drive vessels: the transducer should be mounted between the drives, if possible

• The preferred mounting location for the transducer is on the starboard side of the hull, where the propeller blades are moving downward

       Thru-hull no fairing block required                                                                           Thru-hull with fairing block.

SideVü™ Thru-Hull transducers are installed similarly to a single thru-hull with the exception that a second thru-hull is on the opposite side of the vessel.  There is a cable to connects the pair of transducers, and then a single cable is plugged into the chartplotter. A pair of transducers is required if the deadrise is greater or there is no flat spot on the bottom of the boat.

Mounting a transducer on the trolling motor is a second mounting option available for some transom mount transducers.  Typically, the transducer attaches to the bottom of the trolling motor body.

• Pay special attention and care when routing the cable up the shaft of the trolling motor. It is crucial that when stowing the trolling motor, the transducer cable does not get pinched or worn

• Trolling motor power cable should be routed away from the trolling motor transducer

• Trolling motor should be powered by a battery separate from the chartplotter

• Trolling motors throw off a lot of interference. Use ferrite beads on the transducer cable to help minimize this interference.  Install these near the connector head

Trolling motor mounting is also available for select Panoptix™ transducer as well. Mounting a forward-looking Panoptix transducer to the shaft of the trolling motor will provide the user with the ability to rotate the transducer to look at a specific area without having to turn the entire boat. 

             Traditional Transducer                  LiveScope™ Transducer Shaft Mount                   LiveScope™ Transducer Barrel Mount

Trolling Motor Considerations:

GT transducers and some third party transducers may provide 3D structural down and side view imagery. These 3D structural views require the transducer to remain as straight as possible. As the transducer spins, the imagery drawn is based off of which way the transducers side and bottom surface is facing. These views work best when in a heading hold. Traditional 2D is not effected by the rotating transducer.

NOTE: Garmin's Force Trolling Motor uses a brushless motor and should not produce any electromagnetic interference. The built-in transducer on a Force Trolling Motor uses a 12-pin connector and supports Ultra Hi-Definition ClearVü™ sonar & SideVü™ sonar. The transducer will work with some units that only support regular ClearVu and SideVu imagery.

When placing the transducer through the ice, the top of the transducer needs to be under the bottom of the ice layer. Adjusting the beam width might be needed depending on the depth of the ice. In addition, silty or absorbent lakes, rivers, creeks, or sea beds may prevent bottom returns, as the echo is absorbed and not returned. The same is true in shallow water with hard surfaces. These surfaces may ping back so loudly and hard that they may bounce off the surface of the ice. If adjusting frequency, adjusting beam width, and or restoring sonar defaults do not resolve the issue, moving to another location on the ice may be necessary.

NOTE: With the exception of LiveSope™ Transducers being used for ice fishing, GT Ice fishing transducers do not have built-in temperature sensors.

If the depth or temperature of the Garmin transducer is incorrect, refer to the devices owner's manual.