How to Install a Garmin Fishfinder Transducer

Installing a transducer for a fishfinder can be tricky.

Sometimes even the best fisherman needs a little help, and that help can come in the form of a Garmin fishfinder. The easy part of installing a fishfinder comes in mounting the screen where you can see it. The hard part is installing the transducer, which is the part of the product that converts an electrical impulse into a sound wave, which is sent into the water. It is generally installed onto a boat's transom, located at the stern, or rear, of the craft. Some transducers must be installed professionally.

Things You'll Need

• Drill
• 3/8" wrench or socket
• 5/32" (4 mm) and 1/8" (3.2 mm) drill bits
• Masking tape
• Number 2 Phillips screwdriver
• Marine sealant

Instructions

Choose a Good Installation Location

1. Ensure that the transducer will operate in calm water.

2. Mount the transducer as close to the center of the boat as possible.

3. Mount the transducer where it is not likely to be struck when launching, hauling or storing.

4. Mount the transducer out of the way of the propeller on a single-engine boat. The transducer can cause cavitation, which can degrade the performance of the boat and even damage the propeller.

Mounting the Transducer on the Transom

1. Set your transducer mount at the selected transom location. Take the time to be sure the transducer is parallel with the water line.

2. Mark the center locations of each hole on the transducer mount, using a pencil.

3. Drill the pilot holes approximately 1 inch (25 mm) deep at the locations you previously marked, using the 5/32" (4 mm) bit.

4. Apply the marine sealant to the 5-by-30 mm screws.

5. Attach the transducer assembly to the transom using the 5-by-30 mm screws. Adjust the transducer assembly to extend beyond the bottom of the transom by approximately 1/8 inch (3 mm) on fiberglass hulls or 3/8 inch (10 mm) on aluminum hulls.

6. Adjust the transducer assembly so that it is aligned parallel with the water.

7. Tighten the 10-32 locking nut until it touches the mounting bracket, and then tighten one quarter turn more.

8. Place the first cable clamp on the transducer cable, approximately one-third of the distance between the transducer and the top of the transom.

9. Mark this location. Then, using a 1/8" (3.2 mm) bit, drill a pilot hole approximately 3/8 inch (10 mm) deep.

10. Attach the cable clamp using one of the 4-by-12 mm screws. Coat the screw with marine sealant before installation. Repeat steps 8 to 10 using the other cable clamp.

11. Route the transducer cable to the Fishfinder 300C. Do not cut the cable.

Tips & Warnings

• To avoid drilling installation holes too deep, wrap a piece of tape around the bit at 1 inch (25 mm) from the point of the bit, to help you see when to stop.

• Do not over-tighten locking nuts or other fasteners.

• Avoid routing the transducer cable close to electrical wires or other sources of electrical interference.

References

• Garmin: Fishfinder 300C Installation Instructions