Fish finders are effective devices when fishing in unknown waters. With a power drill, silicone sealant, and fish finder, wiring a fish finder to a fuse box can be a doable process. The following steps will help you wire your fish finder with ease.

Installing the Binnacle Mount

The binnacle mount is the mount of the fish finder. In order to install the binnacle, first, you need to consider several factors before deciding on its location. Keep the fish finder as close as possible to the helm of the ship for the best display as you steer. Placing it chest high will give you an easy, non-fatigue view. Make sure the location allows you to tilt or rotate the unit without obstructing other controls.

The helm station should also have enough clearance and sufficient room for protruding bolts and wires.  

Drilling Mounting Holes

Once you have chosen your location, use the binnacle template included with the fish finder, or the binnacle itself as a template and a pencil, to mark the location of the mounting holes. Using your power drill, make mounting holes running it at full throttle to attain a clean hole and also to prevent edges that cause the surface to splinter.

You will then have to drill an entry/exit point for the unit wires. Before you drill, place the binnacle and fish finder temporarily to ensure there is enough space between the mount and the wire holes to pass through without making sharp bends. This will prevent the wires from twisting unnaturally which may cause chaffing. Also, make sure there is no other hole from a prior gear installation. If there is none, drill the hole directly behind the binnacle mount. It should be large enough to contain the clump of wires.

Applying Silicone Sealant

After drilling the holes, apply silicone sealant around the base of the binnacle mount and around each wire hole. Put the binnacle in place and apply the stainless steel bolts with a dab of silicon on their ends before using them.  The bolt’s finish is important to prevent corrosion. Fasten the bolts to the helm with Nylock aircraft-style locking nut and a stainless steel washer that accompanied the fish finder. Afterward, apply more sealant to entirely seal them off from moisture.

Fuse Selection

To determine which fuse to use, you must first check the electricity draw of your fish finder. Most fish finders draw 1.5A thus requiring a 3A fuse. For a larger fish finder drawing 3.5 A, a 7A fuse is recommended.

Running the Power Leads

Depending on the length of the wires, you may need to lengthen or shorten the power leads. In case you have to lengthen them, ensure you stick with the proper color-coding and tinned-copper boat cable of the manufacturer’s recommended gauge. Ensure you don’t cut out the manufacturers included in-line fuse to prevent invalidating the warranty and also exploding the unit.  The fuse should be installed on the positive lead close to the battery. This will keep the unit safe in case the fuse is fried. 

Push the power leads through the drilled exit hole until the plug has enough freedom to reach the unit without extra wiring outside the helm. Then run the wire to your helms fuse block.  While minimizing droops and slack, secure the wires every 18 inches with tie –wraps or cushioned clamps. For a fuse block with male spade terminals, crease the female spade connectors to the ends of the leads and use heat shrink tubing to protect the connection. In the case of screw-type terminals, use ring connectors with the appropriate size. Don’t connect the terminal’s ends before completing the wiring. 

Mounting the Transducer

For you to have the perfect location of the transducer, stand behind the transom and check for an area deep, free from strakes, through aluminum hulls, or other protrusions interrupting the smooth hull in front of it. This will prevent turbulence which degrades the fish finder performance. It should also be stationed away from the propeller.

Hold the transducer bracket against the transom and adjust its position until its face is horizontal and slightly below the running face of the hull. Use your pencil to mark the location of the bracket’s mounting holes. To the dash, run the transducer’s wire. In case your boat has an old fish finder with a transom mount transducer, cut the transducer at the end and use the old wire to draw the new one. If not, pull the new transducer wire and plug it through.

Once all the wire is pulled to the helm, and routed up through the hole you made, coil any extra line inside the helm and preserve it with tie-wraps. Don’t cut the transducer wire to size. This causes resistance which impedes the sonar detection of the unit.

Referring to the marks you made earlier, drill pilot holes for the brackets mounting crews with your power drill. Use a sealant to coat the screws and the holes of the transom. Holding the bracket in place, screw in the mount. Use a lot of sealants to prevent holes in the transom through the transducer mounting.

Installing Your Fish Finder

Connecting the fish finder directly to the battery works effectively if you use the right cable to connect them. Ensure you protect the wires inside your helm by sealing off the wiring hole you made behind the binnacle mount. After making sure the battery is switched off, connect the power leads, then plug the power and wires into the back of the fish finder.

Test Run

Before you run a test, make sure the sealant you used to seal the transducer mounting holes is completely dry. For some conditions, it may take up to one week, be patient. You need to be sure water intrusion won’t take place.

If you follow all the steps correctly, your fish finder will work effectively. If it doesn’t, the transducer is probably not reaching underwater.


For a visualization of the tutorial above, please watch this short video.

Installing New Marine Electronics in Your Boat - Part One


In conclusion, wiring a fish finder is a simple doing it yourself activity. With the above steps, I hope everything works perfectly.  Now, go have a better experience with your new fish finder.


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