How to Install Fish Finder: Clear Instructions

How to Install a Fish Finder Feature Image

Installing a fish finder in your boat is a great way to increase your fishing effectiveness and they are great tools that will undoubtedly help you on the water, but all boats are different, and the methods to install a fish finder can vary.

Let’s take a look at the methods you can take to install your new fish finder.

How To Mount A Fish Finder: Mounting the Display

Where to position it and correct height

Where you choose to mount your fish finder is the first and one of the most important considerations.

Typically, you will have a fish finder at your steering console, or in the case of a tiller boat, in the rear on the rail of the boat, or mounted to the interior wall as is the case for fiberglass boats.

Using mounts that swivel or gimbal will make this process easy, and the positioning can be less precise due to being able to adjust the angles, allowing for you to see the screen from different parts of the boat.

Flush or Dash Mount

Flush mounting is a nice and clean way to mount a fish finder.

Many boats with consoles have a built-in dash mount, but depending on the age of the boat, the size of the mount may be far smaller than modern fish finders.

You might have the option to cut open the dash to accommodate a much larger fish finder, but this is a best-case scenario.

In many cases for an older boat, that may even include an old outdated fish finder, many anglers will instead just leave their dash as is, and add a gimbal mount on the console, or mount it elsewhere on the dash using the provided mounting system that comes with the unit.

For new boats, the manufacturer will most likely have a dash design that will accommodate a wide variety of fish finders and screen sizes, and the wiring system will easily allow for the installation of a sonar unit.

Gimbal Mount

Gimbal mounts allow you to swivel the sonar unit so that you can see it from the front or middle of the boat.

Gimbal mounts are probably the most popular method to mount a sonar fish finder, and this is true for both aluminum and fiberglass boats regardless of their age.

Gimbal mounts can be mounted almost anywhere, from a bench seat on an old aluminum boat, the top rail space on the side of a boat, the inside wall of a fiberglass boat (not the hull wall) or on the floor of a deck.

Gimbal mounts allow you to swivel the sonar unit so that you can see it from the front or middle of the boat, and if your screen is big enough, possibly from one end of the boat to the other, depending on boat size.

How to Mount a Fish Finder: Mounting the Transducer

Types of Transducers and Cable Setup

Cable setup varies greatly from one boat to the next, and it can be a challenge to run the cable through the hull and out of sight.

In many cases, your boat will have a hole near the top rear of the boat for you to run your transducer cable to the interior of the boat without requiring any drilling.

For the power wiring to your boat batteries, as well as with the transducer and unit link cables, you will have to find a way to run there in the interior of the boat.

Some boats will have dedicated channels or tubes to run the cables and you will have to use an electrician’s fish cable to chase the wires through, and that’s the hard part.

Some boats do not have dedicated channels or tubes to run your electronics cables, and this is typically the case with older boats, you will have to get creative and run them through storage compartments or rod lockers.

Zip ties will be your best friend in these adhoc situations and you should try to make them as secure as possible to prevent wires from pulling loose, or from getting hooked and tangled on fishing rods or gear.

Transom Mount Transducers

When mounting a transducer to your transom, you need to choose the location that is closer to the bottom edge of the boat, close to the outboard engine.

Transom mount transducers are by far the most popular transducer used by anglers in freshwater and they are very common among saltwater boats under 30 feet in length as well.

When mounting a transducer to your transom, you need to choose the correct location, and in most cases, this location will be closer to the bottom edge of the boat, close to the outboard engine.

Down imaging transducers can also be mounted in the “cubby hole” area where the water intakes for your live wells are located, directly behind the motor itself.

The location also needs to be level with the bottom of the boat or just above the bottom edge of the boat to prevent your transducer from contacting the bottom of sandbars or timber, thus getting damaged.

For side imaging transducers, your location is very important. The transducer may work in the same location as a standard sonar transducer, but in many cases, it should be mounted to the side and perfectly level.

Side imaging transducers need to be clear of obstructions such as the boat motor itself, or the sonar signal will be blocked and you won’t see any readings on your fishfinder.

Fishfinders will come with all the hardware needed to mount the transducer in most cases unless otherwise noted by the manufacturer, and you will need to use some type of marine silicone to ensure that the holes you drill to mount the transducer are watertight and will not leak.

Through-Hull Transducers

In-hull transducers used to be more common among freshwater anglers before side imaging came along, but some anglers still use them today. Saltwater anglers still probably use in-hull transducers more extensively than freshwater anglers.

In-hull transducers do have a major con. Since in-hull transducers have to read through the hull of the boat, your returns can be inaccurate, especially in deeper water.

The inaccuracies depend on the thickness of your hull, and while you will likely be fine when using one in a bass boat or standard aluminum boat, very large boats with hulls that are .5 to 1 inch thick will likely have these issues when fishing.

When mounting an in-hull transducer, you will need to purchase a mount that allows the transducer to sit level and shoot straight down on what is normally an angled hull.

One of the pros of using an in-hull transducer is that you don’t need to drill any holes, and unlike the transom of a boat, drilling holes in the bottom of your boat is never a good idea.

Using an angle finder or an angle finder app on your phone, you can determine the angle or pitch of your hull, and on most mounts, they will have marked around the circular mount numbers and lines for different angles.

Using silicone, you place the mount onto the hull and line up the number for your boat hull angle so that is it parallel with the transom.

Once the mount is installed you need to fill the mount with fluid so that there is no air to disrupt the signal, and you can do this using standard antifreeze for your car or vehicle.

Be sure to fill the cavity close to full, so that when you do the final installation of the transducer to the mount antifreeze comes gushing out, this will ensure there is no air in the mounting cavity, and push the unit until it is fully seated and locked.

Through Hull Transducers

Through-hull transducer fish finders aren’t really used in common fishing boats, with the exception being large saltwater fishing boats.

The reason for this is that the installation is much more complicated, and you have to drill holes in the hull of your boat to mount them.

Through-hull transducers are commonly found on sailboats to help the operators to determine the depth and keep the boat from running aground.

To mount a through-hull transducer, you need to drill a hole through the bottom of the mount and insert the threaded insert, and also ensure that the mount is leakproof and will last.

From there you can insert the actual transducer by screwing it into the threaded female insert that you installed in the hull.

Some through-hull transducers have a fairing block that mounts to the outside of the hull and extends out from the bottom of the hull by an inch or so, but as mentioned earlier, these transducers are commonly found on large saltwater boats that are rarely trailered and spend most of their lives in a harbor or boatyard when not in use.

Final Tips on How to Mount a Fish Finder

In most cases, mounting a fish finder transducer mount and the fish finder itself is not very complicated. You just need to be sure that the transducer location is correct and that you are happy with the positioning of your units in the boat for easy viewing.

The work will be worth it in the end, and you will never want to fish without a fish finder in your boat ever again.

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Shawn Chapin is an experienced fishing writer and guide based in Wisconsin, where he loves targeting muskie and a range of other species. Shawn's fished extensively for pike, largemouth bass, smallmouth and panfish species. He's developing a passion for chasing trout on the fly rod.
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