How to Install Fish Finder Transducer

Fish Finder Guides

If you’ve just purchased a fish finder and have trouble figuring out how to install it, keep reading for the most straightforward techniques. This article mainly deals with the installation of fish finder transducer. Refer to our article for the installation of fish finder head unit here: Fish Finder Mounting Ideas.

Where to Install Fish Finder Transducer

There are several ways to install the fishfinder transducer. Each nethod comes with its advantages and challenges. We’ve included the most common methods to install a transducer and a few tips you need to know to choose the best site on your vessel.

Transducer Installation types:

  • Trolling motor hunt
  • Transom mount
  • Thru-Hull mount
  • Pole mount
  • In-hull mount

While each method is viable, generally, the trolling motor and the transom are the most commonly used options. The other choices are excellent for specific circumstances.

Installing Transom Mount Transducer

The first thing you want to do when installing a transom mount transducer is to determine the best location on the boat. The placement will try, for example, if you’re installing it on a single-drive boat versus a twin-drive boat.

best trasnducer mounting location on the transom

Useful tips:

  • The best mounting height for the transducer is the bottom edge of the transom. The bottom surface of the transducer should protrude between 1/32″ and 1/16″ past the bottom of the vessel. 
  • Install the transducer on the right side of the boat, where the outboard propeller strokes downward. 

Ensure that the transducer should not be in a downstream location of any struts, fittings, strakes, discharge ports, or water intake. Essentially, nothing that causes turbulence or air bubbles should be near the transducer. Because the fish finder will have depth reading problems when the transducer has propeller wash or air bubbles on it.

Mount your transducer in a position parallel to the waterline. Be mindful of the transducer height on a plane at high speed, as it should be below the water level so that it doesn’t lose depth when planing. You’ll need to apply a marine sealant to all screw threads to prevent leakage into the transom. 

transducer mounting angle guide

On twin-drive boats, install the transducer in the middle of the motors, which is generally the best location in relation to the downward swing of the propellers. 

Installation:

  1. Dry fit the transducer.
  2. Drill pilot holes after dry fitting the transducer.
  3. Use a marine sealant with your screws to secure the transducer. Ensure that you allow an ample amount of time to dry thoroughly. 
  4. Install the transducer cable cover high enough above the waterline. It should extend ⅜” below an aluminum hull and ⅛” past a fiberglass hull.
  5. Run your cable to verify that they fit correctly. 
  6. At this point, you can add your ferrite beads. 

Installing Transducer on Trolling Motor 

When you install the transducer on the trolling motor, you’ll start by deciding where precisely on the motor to place the device.

If you have a standard transducer with side or down imaging, it goes on the bottom of the trolling motor, allowing it to face down underneath the boat.

standard trunsducer mounted on trolling motor

A live sonar generally goes on the same side as the shaft. The best positioning is downward facing for the most accurate readings. 

live sonar mounting on trolling motor

If you have a mounting kit, then you will start by assembling the mounting clamp and the bracket onto the transducer using bushings, screws, and bolts. 

  1. Start by sliding the transom bracket through the transducer adapter in the kit. 
  2. Put the bushings on the right and left sides of the adapter. 
  3. Use the bolts to tighten both sides until it’s at the desired angle. 
  4. Slide the clamp through the port on the bracket while ensuring the transducer is facing straight down.
  5. Ensure that the wire does not get hung up on the cradle. You do not want the cable to hang near the propeller as it can get caught between the fin or the blade.
  6. Tighten the clamp until the transducer fits snugly but not too tight. You may have to cut off any excess clamp that hangs over, as you don’t want it to interfere with the movement of the propeller. 

You’ll be able to adjust the transducer as necessary (forward or backward), depending on the type of bracket you purchase and your preference. It should always be in contact with the water but not able to slide forward or backward. Whichever position you choose, it should be locked into place. 

Be sure that you leave some slack in the cable when you run it along the top, so it doesn’t get hung up anywhere when shifting.

In-Hull Transducer Installation 

In-hull transducer works well in a single thickness fiberglass boat. Beware that in-hull transducer doesn’t perform optimally in wooden or metal hulls.

in hull transducer installation illustration

The best location to install inside the hull are the areas that are free of turbulent water. You should avoid ribs, stakes and other protrusions as these areas create turbulence. The transducer should be located as close to centerline of the hull and to the stern as possible in order to remain in contact with water at the high speed.

You will not be able to change the position of the transducer after it is installed. It’s best to do a trial installation first and check the transducer performance at various speeds of the boat.

Installation Instructions:

  1. Clean the work area for installation and make sure that the area is clear of any wires or obstructions before you begin working.
  2. Locate the best possible place for the transducer. Keep in mind that ideally, you want the transducer to be on the flattest surface possible. 
  3. Use a power drill with a scotch Brite pad or 80 grit sandpaper to rub the surface if you have one to make this process quicker and easier.
  4. Take a rag or a cloth and use some acetone to clean the abraded area.
  5. Expose the adhesive side of the guide ring by removing the backing and installing the ring in the exact spot where the transducer will rest.
  6. Be sure the epoxy mixtures have been mixed well to allow all of it to cure. When the mixture becomes cloudy, you’re all set. 
  7. Fill the guide ring until it’s full with the epoxy mixture. 
  8. Determine how the transducer should be placed inside the hull by identifying its shape and place it faced down.
  9. When installing the transducer, make sure that the wire is facing towards the back. Additionally, hold the transducer in place for the recommended wait time to make sure that the epoxy cures completely. 
  10. Don’t forget to clean your work area and run all the wires back to the unit where they will connect.

Thru-Hull Transducer Installation

Before you start, keep in mind that you’ll be cutting a hole through the bottom of the boat, so you shouldn’t attempt this project until your vessel is up for the winter or needs maintenance. 

Additional guidelines to know:

  • The flowing water located under the hull has to be smooth with a minimum amount of turbulence and bubbles, especially at high speeds.
  • The transducer must be in a position where it’s continually submerged in water.
  • The transducer beam must not be obstructed by the propeller shaft(s) or the keel.

Installing the Transducer

  1. Guide the cable through the hole where the transducer will be mounted, from outside the hull. 
  1. Next, push the transducer’s stem through the mounting hole while twisting it simultaneously to squeeze any excess sealant. Be sure to line up the transducer with the blunt/arrow/button, facing frontwards in the direction of the bow. Be sure that the centerline of the boat and the long side of the boat are parallel with one another.
  1. If you have a stainless steel transducer and you’re installing it inside a metal hull, make sure that the isolation sleeve is positioned between the hull and the transducer stem. 
  1. Prevent the sleeve from interfering with tightening the nut by positioning the isolation sleeve below the hull nut.
  1. While you’re inside the hull, slide the hull nut and the backing block onto the cable. 
  1. Against the hull, place any backing block; furthermore, make sure that the arrow end is facing frontwards in the direction of the bow. 
  1. Next, twist on the hull nut before tightening it with pliers. 

Check for Leaks

Once you’ve placed the boat in the water, check for leaks around the transducer immediately. Be mindful that some small leaks may not be apparent at first. Furthermore, do not allow the boat to stay in the water for three hours or more before checking for leaks again.

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