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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

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.

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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.

  • Eytan from Chestnut Hill

    Posted on 9/5/2019

    You mention a second battery for the audio system but how do you prevent said battery from depleting within an hour of connection of the radio system.

    Alexander H. from Crutchfield on 9/6/2019
    Eytan, they're typically deep-cell batteries, so their performance life is a little longer than the average battery. Check the Details tab on the battery you have in mind for amp hours yield. Keep in mind that the second battery will also be connected to the alternator so you'll be able to charge it up as needed, and as "second battery" you'll still have your primary battery in play.
  • Renee turner from Naperville

    Posted on 8/14/2019

    I am replacing a stereo in my 32 ft envision and the stereo is currently powered by a rocker switch in the mid cabin. Can I wire in the power of a 1000watt infinity amplifier to the same power wire I use for the stereo which is controlled by the rocker switch? I still plan on running the ground to the amp to the battery.

    Alexander H. from Crutchfield on 8/15/2019
    Renee, you'll need to run a new power and ground to the battery. Be sure to check the manual for the proper gauge for the wire or give us a call and we can help.
  • Dennis Habel from Kapuskasing

    Posted on 6/25/2019

    I have installed a bluetooth boss marine system in my bayliner. Everything works great but as soon as I crank my engine the music stops and it stays off until I turn my engine off. I have grounded it to the chassis I have a fuse I even connected just the stereo system to a separate battery and it's still happening ? Any ideas ?

    Alexander H. from Crutchfield on 6/27/2019
    Dennis, it could be that the stereo is not properly grounded. Try grounding it at the battery itself and see if the problem persists. Also, keep in mind that if you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.
  • EddieRock from Lake Minnetonka Area

    Posted on 6/18/2019

    I have a Sea Ray with a battery isolator (Battery switch/selector that says 1, 2 or Both). Typically, when I'm anchored, I switch to one of the batteries and run the stereo. Then if I run the battery dead, I switch to the other battery and start the boat. With that said, is there a place down stream from the isolator that I should hook the positive lead? I see that my negative is run to both batteries so it wouldn't matter which battery I should hook the ground (negative) to.

    Alexander H. from Crutchfield on 6/26/2019
    Eddie, we consulted Tech Support on this. A battery isolator generally allows toggling between two different batteries to power the same load. For instance, a starter and accessory panel in the craft which are both connected to the "Common" output of the isolator. These items will receive power regardless of the position selected on the isolator, assuming both batteries are charged. The answer to your question is really based on how you want the system operate. If you literally only want the stereo to operate as long as one specific battery has a charge, you would connect it between that battery and the isolator input. If you actually want to select the battery you want to wear down while you're anchored, then switch to the fresh battery to start and run, still enjoying your tunes, connect the system to the "Common" side of the isolator. Keep in mind that if you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.
  • Jonathon M from Columbus Ohio

    Posted on 5/21/2019

    I have a pontoon I'm getting ready to hook an amplifier into with a sub and speakers. However, I do have the two battery system. I typically alternate every time going out. Is there a way to hook up the amp to both batteries so it alternates just as everything else in my boat does when I alternate each boat session? The batteries are identical. Wondered if I could do some type of split or secondary wire. I didn't think it was good to run on "all" on my battery switch vs 1 or 2 which is why I always alternate each time.

    Alexander H. from Crutchfield on 5/24/2019
    Jonathon, I've passed along your idea to our Advisors. Someone will contact you soon to help find the right gear for the job if it's possible.
  • Nick Thomas from Johnsonville

    Posted on 5/20/2019

    Would it be best to run Power/Ground on opposite sides of the boat from each other to eliminate interference or should that not be a normal issue?

    Alexander H. from Crutchfield on 5/21/2019
    Nick, it'll be fine to run power and ground on the same side. Ideally, you'll want to run signal as far as you can from power — that's how unwanted noise could come into play.
  • Tegan Underwood from Aurora

    Posted on 5/14/2019

    Hi. I having issues hooking up speakerins in my boat. I have both power and ground ran back to my battery but when I try to connect the ground to the battery I am getting a lot of sparks. What could be causing this?

    Alexander H. from Crutchfield on 5/17/2019
    Tegan, have you secured the connection and is your amp powered? Or is that not happening? You'll see a spark when you connect the ground to the negative terminal, but you'll still secure the connection. Any sparking should stop. If it does not, disconnect from the battery and give our Tech Support a call. If you bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.
  • Knot Connected from Green Bay, WI

    Posted on 5/9/2019

    What about remote power-on relay? I'd like to be able to run the amp while on shorepower, so I don't want to wire the power-on relay to the ignition. Despite having a dedicated house bank, I'm still concerned about having a toggle switch to power up the amp and forgetting about it.

    Matt Freeman from Crutchfield on 5/17/2019
    Knot, if you're using an aftermarket stereo, it'll have a turn-on lead that connects to the amp, so that the amp only turns on when it receives signal in the turn-on lead. So, when you turn the house bank off, thus turning the stereo off, the amp will turn off as well because it isn't getting signal from the turn-on lead anymore. If you have further questions and bought your gear from Crutchfield, you can call Tech Support for free help troubleshooting your system. If you purchased your equipment elsewhere, you can still get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.
  • Max from Seattle

    Posted on 4/7/2019

    Installing a 1600 watt amp on my boat and battery is located about 20+feet from mounting location due to the weaving around compartments. Can I run power to the helm switch panel, and the ground to the buss bar rather than home runs to the battery?

    Alexander H. from Crutchfield on 4/8/2019
    Max, if you do so, let us know your results. In the same case, we'd still ground at the battery.
  • Ted Gifford from Lisbon

    Posted on 2/6/2019

    This is regarding the proper ground for my boats stereo. My boat currently has a stereo/4 speakers/2 batteries. I decided to upgrade and add an amp. So I have replaced all parts with new. I have read your comments and have seen your diagrams which i understand. But my install instructions say the ground for the amp should only be about 3 feet or so. Where you say run the ground wire to the battery.....Which is about 15' away. What is the correct or proper way to do it without damaging any components? If I do as the instructions say.....my question then would be.....would my bow rail be considered as a good ground source? There are ss bow rail bolts thru the hull that are close by.

    Alexander H. from Crutchfield on 2/11/2019
    Ted, the most reliable ground on a boat is typically going to be the battery. Even at that distance, you'll likely be better off.
  • John from Raleigh

    Posted on 1/3/2019

    Is there a maximum length of positive and negative cable from the amp to the battery? In my case the batteries are in the back of the boat but the amp is in the center console. Probably a distance of 12 feet + or -

    Alexander H. from Crutchfield on 1/4/2019 John, your amp manual should give recommendations on power/ground wire gauge, but you may want to step up the gauge. I've passed your question along to Advisors. Someone will contact you soon to help you get the best gear for the job.
  • 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.

  • 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.

  • 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.

  • 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!

  • 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.

  • 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!

  • 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

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