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Installing an amp on a boat: running power and ground wires

It's simple — just run the wires to the battery

A circuitous path, involving England, New York, rural Michigan, Indiana, and lots of parts in between brought Matthew Freeman to Charlottesville, where he's been writing about mobile audio/video for Crutchfield off and on since early 2000. He fosters an eclectic taste in film, and is fond of a wide range of music. A native of Albuquerque, New Mexico, he found his way to the University of Notre Dame, where, in an act of charity unsurpassed in the history of Western civilization, he was given a B.A. in English.

More from Matt Freeman

An amp on a boat

"Where the heck do I ground this thing?" I can neither confirm nor deny that I said something to that effect the first time I installed an amplifier on a boat.

Boats are not the same as cars

You see, I was used to installing amps in cars, and when you do that, you run power wire directly to the car battery, and secure the ground wire to bare metal somewhere on the vehicle's chassis. But on a vessel made primarily of fiberglass and wood, this just isn't an option.

[Give your boat's stereo system a power boost it needs with a new marine amplifier]

The ground wire goes to the battery

Luckily, the solution is simple: you run both wires directly to the battery. Well, to the secondary batttery, that is. All boats will have a primary battery for ignitiion and critical electronics, and a second battery for everything else that needs power. "Everything else" includes your stereo system. 

Marine amplifier wiring

So just like with automotive applications, you connect the power wire directly to the positive battery terminal, and include a fuse and fuse holder no more than 18" from the battery. But unlike a car, instead of hunting for a factory bolt that touches bare chassis metal, you simply run the ground wire along the same path and attach it directly to the negative battery terminal. Finish the signal and speaker wiring, mount the amp, and you're ready to rock.

[Check out our selection of marine-rated wiring for your amps and speakers]

Crutchfield — we're here to help

If you're on the fence about whether or not your boat needs an amplifier, read our Marine Amplifier Buying Guide for more information. If you're new to the idea that your boat can have a great-sounding stereo system or aren't sure what your options are, take a look at our library of marine audio articles.

And remember, when you buy your gear from Crutchfield, you get free lifetime tech support. Over the phone, our Virginia-based techs can offer you the guidance you need to successfully install your new gear on your boat.

  • ME

    Posted on 3/13/2017

    What if your boat only has one battery. can you still hook the amp straight up to that and run your system? or what do you suggest to do

  • Dave

    Posted on 5/25/2017

    Perfect! Just what I need to hear! New amp is due today- now I'll be ready to install!

  • Matt Freeman from Crutchfield

    Posted on 7/25/2017

    ME, sorry for the delayed response! If you're planning to run a sound system on your boat, you'll want to buy and install a secondary battery and its attendant wiring. The last thing you want when you're out on the water is to drain your main battery by running your stereo and be unable to start your boat. So a secondary battery is a must for anyone who wants to run a sound system. These batteries often also provide power to things like fishfinders, depth gauges, and other fun accessories, leaving the main battery free to power just the ignition and select other critical electronics.

  • RJ Harding from Jenks

    Posted on 8/17/2017

    On a Cruiser, Can you hook up the positive and ground, on the amp, to the 12v lead and ground coming into the cabin panel? That would make life much easier!

  • Ryan

    Posted on 8/20/2017

    What can you do if you're getting lots of feedback from the engine? Tried thicker gauge wiring. It's tight and secure. Tried switching the hookup to different battery, still lots of engine feedback when running. Sounds great with engine off.

  • Robert Ferency-Viars from Crutchfield

    Posted on 8/21/2017

    RJ, do those power and ground leads go back to a secondary battery? If so, the yes! The main point is that you don't want to connect power-hungry components (like an amplifier) to the battery that is also responsible for starting your engine when it's time to go home.

  • Matt Freeman from Crutchfield

    Posted on 8/22/2017

    Ryan, a few questions for you to work through: 1) Where is the amp grounded? 2) Is the ground wire making contact with bare metal? (No paint, no coatings of any kind.) 3) Are the power wires and preamp RCA cables running down the same side of the vehicle? If so, the power cables could be bleeding noise into the RCA cables. Routing these cables down opposite sides could be the solution.

    But before doing that, the next step is to figure out where the noise is coming from: Test the RCA cables at the amp's inputs. Unplug each one one at a time, leaving the others plugged in. If the noise goes away when a given cable end is unplugged, you've found the culprit. Try rerouting the cables to get as much separation between the power wires and the RCA cables as possible.If the patch cables aren't the problems, you can do a similar diagnostic test with the speaker wires.

    Lots of things can contribute to noise in the car, but most likely, it's the ground connection that's the issue. It's worth checking the receiver's ground connection as well. For more info on noise diagnostics, check out this article.

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