Shoot-Thru-Hull Installation

To avoid drilling a hole to mount a thru-hull transducer, a transducer can be secured with epoxy inside a boat (shoot-thru- hull installation). This type of installation can provide better noise reduction and allow you to use a higher Gain setting. For a transducer to be mounted inside the hull (shoot-thru, not thru- hull), the boat must be fiberglass, with no core. Contact your boat manufacturer if you are unsure. Professional installation might be necessary. Be sure to always wear a dust mask and safety goggles.

Some transducers are specifically designed to be mounted inside a fiberglass hull. The standard plastic transom mount transducer can also be mounted using this method. If using a temperature sensing transducer, the temperature shown reflects the hull temperature.

Installing the Fishfinder 340C > Mounting the Transducer

NOTE: Many modern hulls have a dedicated pocket for shoot-thru-hull transducer installation. If you are unsure if your hull is equipped with a pre-located pocket, contact your hull manufacturer.

To test the location:

1.Fabricate a test device from a section of PVC pipe or a can, as shown in the following illustration.

2.Temporarily seal the test device to the hull with caulking or RTV sealer, and fill with water or light mineral oil.

3.Place the transducer in the water, pointed directly at the bottom and weight it down. Set the unit for optimum performance. If the sonar performance is significantly degraded, another location must be tested.

Selecting a Location for a Shoot-Thru-Hull Installation When installing a transducer, the installation location must be the following:

•Solid fiberglass, without any air bubbles, laminates, fillers, or dead air space.

•In an area of clean (non-turbulent) water at all speeds.

•The location must not be over any strakes or behind any obstruction on the hull that would create turbulence at speed.

Strip caulk or RTV sealer

Hull surface

PVC pipe

or a can

Weight the transducer to hold it in place.

Fill a pipe or can with water

or a light mineral oil.

Testing the Location

Fishfinder 340C Owner’s Manual

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