Installing the Fishfinder 400C

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.

PVC pipe or a can

Strip caulk or RTV sealer

Hull surface

Weight the transducer

to hold it in place.

Fill a pipe or can with

water or a light mineral oil.

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.

Testing the Location

To permanently install the transducer:

1.Lightly sand the surface of the hull and face of the transducer with 400 grit wet or dry sandpaper.

2.Build a dam using strip caulk about 1/4" (6 mm) tall. Pour about 1/8" (3 mm) of two-part, slow-cure epoxy into the dam.

3.Place the transducer in the epoxy, turning the transducer to work out any air bubbles.

4.Weight the transducer in place, and allow it to cure for 24 hours.

Fishfinder 400C Owner’s Manual