How to Install a Fish Finder on a Boat

How to install a fish finder on a boat breaks into four jobs: pick a spot for the display where you can see it and reach the keys, fasten the mount (a tilting bail mount, a swivel base, or a flush cutout in the dash), install the transducer and run its cable to the back of the unit, then connect power exactly as your unit’s installation instructions describe. A short setup on the screen finishes the job.

This guide is general product information, not repair or electrical safety advice. Follow the installation, wiring, and charging instructions in your product’s manual, stop using any battery, charger, or electronics that overheat, swell, or smell of burning, and contact the manufacturer.

Your own model’s instructions always come first. The steps here follow Garmin’s ECHOMAP UHD2 5x/7x installation instructions, which warn that a poor install can cause injury, vessel or device damage, or poor performance.

Before You Start: Parts, Tools, and Ground Rules

Lay out what came in the box. Garmin’s STRIKER 4 product page, for example, lists the unit, a dual-beam transducer, transom and trolling motor mounts, a tilt/swivel mount, a power cable, and documentation. Match the parts to your manual’s list before you start.

The ECHOMAP UHD2 instructions also set ground rules worth following on any boat:

• Install on land or at a calm dock. Garmin says to install the device only when the vessel is on land, or properly secured and docked in calm water.
• Disconnect the boat’s power first. The instructions say to disconnect the vessel’s power supply before beginning the installation.
• Protect yourself when drilling. Garmin calls for safety goggles, ear protection, and a dust mask when drilling, cutting, or sanding.
• Look behind the panel. Always check what is on the opposite side of a surface before drilling or cutting.

Choosing Where the Display Goes

Plan the whole layout before anything becomes permanent. Garmin’s ECHOMAP UHD2 instructions and its ECHOMAP Plus mounting considerations list the same four requirements:

1. A clear view of the screen and access to the keys. On a bass boat, check the console unit from the driver’s seat, not from the dock.
2. A surface sturdy enough to support the device and the mount.
3. Cables long enough to reach. The cables must be long enough to connect the components to each other and to power, so trace the transducer cable’s route before you commit.
4. Distance from a magnetic compass. To avoid interference with a magnetic compass, Garmin says not to install the device closer to a compass than the compass-safe distance in the product specifications. For the ECHOMAP UHD2 5x models that figure is 3 in.; for the 7x models it is 5 in.

The STRIKER Vivid owner’s manual adds that a GPS unit needs a clear view of the sky, so one mounted inside a cabin should be close to a window.

How to Install a Fish Finder on a Boat: Mounting the Display

Garmin describes three ways to mount the ECHOMAP UHD2 5x/7x. The bail mount lets you tilt the device, the swivel base and bail mount together let you swivel and tilt it, and a flush mount sets the device into the dashboard for a more integrated installation. The ECHOMAP Plus page notes the swivel mount is not available on ECHOMAP Plus 9x models.

Bail Mount (Tilt)

The ECHOMAP UHD2 steps: use the bracket as a template to mark pilot holes, drill them with a bit sized for hardware suited to your surface, fasten the bracket, loosely fit the knobs, set the device in the bracket, and tighten the knobs. On fiberglass, Garmin recommends using a countersink bit to drill a clearance counterbore through only the top gel-coat layer, which helps avoid cracking the gel coat when the screws are tightened.

Swivel Base (Tilt and Swivel)

A swivel base sits under the bail mount so you can turn the screen. For the ECHOMAP UHD2 5x/7x, Garmin has you use the base as a template for three pilot holes drilled with a 1/8 in. bit, seat the lock nut under the base, screw the base down, then bolt the bail bracket on top without over-tightening. Garmin warns that only pan-head machine bolts or self-tapping screws should secure the swivel base, because countersunk screws can damage the bracket.

Flush Mount (In the Dash)

A flush mount means cutting a hole you cannot undo. In outline, Garmin’s ECHOMAP UHD2 5x/7x sequence is:

1. Trim the flush-mount template and confirm it fits where you want the unit, then secure it to the panel.
2. Drill starter holes inside the corners of the solid line (Garmin specifies a 3/8 in. bit for this model), then cut along the inside of the line with a jigsaw or rotary tool.
3. Check the fit, refine the opening with a file and sandpaper if needed, then line up the mounting holes with the template and drill the pilot holes.
4. If you will not be able to reach the back of the device once it is mounted, connect the power and transducer cables now.
5. Fit the adhesive rubber gasket pieces to the back of the device, place it in the cutout, fasten it with the included screws, and snap the trim caps in place.

Garmin notes there is only a small amount of clearance between the case and the mounting holes, so cutting the hole too large could compromise the stability of the device. And a metal pry tool can damage the trim caps, so Garmin suggests a plastic one. Check the depth behind the dash, too: Garmin lists the clearance needed behind the chartplotter as 2 1/4 in. for the 5x models and 2 7/16 in. for the 7x models.

Installing the Transducer and Running the Cable

The display is only half the system. Garmin’s ECHOMAP UHD2 instructions say to follow the instructions provided with your transducer to install it on your boat; those instructions hold the placement rules for your hull and motor. Placement on the hull is a separate job from mounting the screen, and a trolling motor mount has its own clamp and cable routing.

The cable run back to the display follows a few rules:

• Keep it away from noisy wiring. Garmin says to route the transducer cable to the back of the device away from sources of electrical interference. Its transom and trolling mount transducer instructions name ignition wires, house and trolling motor batteries and wires, and high-energy wires such as radar, audio amplifier, and autopilot pump wires.
• Do not shorten it. The same instructions say cutting the transducer cable voids the warranty; coil the spare length instead.
• Match the plug to the port. The ECHOMAP UHD2 5x/7x has a 4-pin transducer port marked XDCR. If an existing transducer’s plug does not match, Garmin says a transducer cable adapter may let you connect it.
• Seat the connector fully. Align the divot on the connector with the keying on the port and push firmly until it is fully seated. Garmin warns that misaligned pins could damage the device.

Power: What to Know Before You Connect

This guide does not walk through wiring a fish finder to a battery or a switch panel. Follow the power section of your unit’s installation instructions, written for that model. Three principles from Garmin’s ECHOMAP UHD2 instructions explain why:

• The fuse stays in. Garmin warns not to remove the in-line fuse holder when connecting the power cable, and says the appropriate fuse must be in place as indicated in the product specifications to prevent injury or product damage caused by fire or overheating. Connecting without it also voids the warranty.
• Grounding comes before power. The instructions say to make sure the device is properly grounded, following the guide, before applying power.
• Extending wires has rules. If the power and ground wires need to be longer, the instructions set a minimum wire size for that model. Do not guess it from another unit.

If your boat’s battery layout, switch panel, or existing wiring is not clear to you, or if the instructions do not match what you find under the console, have a qualified marine electrician make the power connection.

First Power-On: Setup Checks

With everything connected, run through the setup:

1. Update the software. The ECHOMAP UHD2 instructions say you may need to update the chartplotter software after installation, and Garmin’s transom and trolling mount transducer instructions say you must update it when you install that transducer.
2. Confirm the transducer type. The STRIKER Vivid manual says that if you connect a transducer that was not included with the unit, you may need to set the transducer type, and that Auto Detect lets the unit find it. Garmin warns that manually selecting a transducer could damage it or reduce its performance.
3. Decide how depth should read. The same manual describes a keel offset that adjusts the depth reading for where the transducer is installed, so you can see either the depth below the keel or the true water depth.

On the water, start slow. Garmin’s transducer instructions explain that the transducer must be in the water to work, so you cannot get a depth reading on the trailer. Confirm a steady depth and a solid bottom line at idle, then raise speed gradually and note where the bottom drops out, if it does. Garmin’s transom-mount instructions treat a signal lost at speed as a transducer position problem. If there is no sonar at all, the STRIKER Vivid manual says to make sure the sonar cable’s locking ring is secured, sonar is enabled, and the correct transducer type is selected; for a noisy screen, it says correcting installation issues is the best way to eliminate interference. Check for leaks around any new screw holes below the water line before leaving the boat in for long.

A permanent install isn’t for everyone. If you fish from rental or borrowed boats, a portable kit skips the drilling. For networked systems or a thru-hull transducer, a dealer or marine installer is the cautious choice. For units and the transducers they ship with, see our Fish Finders section; for brackets and transducer mounts, the Mounts & Transducers section; and for how we score products, How We Review.

Frequently Asked Questions

How do I install a Garmin fish finder on my boat?

Follow the installation instructions for your exact model: choose the location, fasten the mount, install the transducer by its own instructions, connect its cable and power as described, then update the software.

Can I install a fish finder myself?

Garmin’s instructions say to contact Garmin Product Support if you experience difficulty during the installation. Hand the power connection to a qualified marine electrician if your boat’s wiring is unclear, and use an installer for any job that cuts into the hull.

Do I have to drill holes to install a fish finder?

For a fixed install, usually yes: the bail mount and swivel base are screwed down, and a flush mount needs a cutout. A portable kit, such as the STRIKER 4 Portable Bundle that Garmin’s STRIKER 4 page lists with a suction cup mount, is one way to skip drilling.

Why won’t my fish finder turn on after installing it?

The STRIKER Vivid manual ties this to the power supplied to the device. Its first checks are whether the power source is working (other devices on it running, for example) and whether the correct fuse, as shown on the cable label or in the installation instructions, is in the power cable’s holder. If power looks right, the manual says to contact Garmin product support; anything beyond those checks belongs with a marine electrician.

About the author