Installing new equipment on a boat often requires new electrical wiring. Two tips for running that wiring in tight spaces.

Pulling Electrical Wires

Running new electrical wires on a boat generally is no fun. More often than not, where they need to go is hidden in the bowels of the boat, twisting and turning.

Last summer, we installed a new refrigerator. It runs on 12 volt electricity instead of propane as the previous one did. Overall, that would make it much more efficient.

There was just one problem: we had to run new wiring for it. There wasn’t any old wiring to even use as a guide – we were going from scratch.

It didn’t seem like it would be a big deal: straight line, it would be about an 8 foot run. The way it had to run, though? About 18. And all hidden behind panels that could not be removed. There were a couple of access points in the middle but they had very tight cut outs. No way would we be able to just snake a wire from one end and expect it to come out where it should.

NOTE: Read the comments for some more great tips from readers!

Tip 1: Electrician’s Fish Tape

Electrician’s fish tape is designed for just such things. It’s a springy, semi-flexible wire tape that comes on a reel in various lengths.

Feed it from the end with the more restricted opening (hopefully you can reach to it and wiggle the end of the tape through, then push it towards the other opening. The tape is rigid enough (unlike the wiring) that it will go straight and not just ball up when it hits an obstruction. Feeding the tape is easiest with two people, one to push it and then sweep it from side to side and the other to yell “stop” when they see it in the other opening and grab it. It’s possible to do by yourself, though – it just takes a lot of going back and forth, moving the fish tape just a little at a time.

In the past, we’ve always been able to pull the new wire through by simply taping it to the fish wire and gently pulling. Not this time! The opening was tight enough that joint would be pulled apart and we’d have to feed the fish tape all over again. It only took me two failed attempts to decide there had to be a better way.

Tip 2: Crimp on a Screw Connector

I needed a connection that wouldn’t come apart even when I tugged on it to get it through the tight spots. The fish tape had a nice eye on the end; I just needed a way to attach the wire to it. First I tried stripping a section of wire and then passing it through the eye and twisting it back together and taping it. Nope, it pulled apart again.

I finally decided to sacrifice a screw connector. I crimped it onto the wire, then used a cable tie to attach it to fish tape. I put a little wrap of electrical tape over the joint so that it was nice and smooth and wouldn’t snag. It held perfectly, even with me having to tug a fair amount to get it though one blind spot. I couldn’t believe how easily it worked. After the wire was run the whole way, I just cut it off

You can see both the end of the fish tape and the screw connector I crimped to the wire in the photo above. The big thing in buying fish tape is to get one that is stiff enough to push through a narrow opening. Because they’re made of stiff metal, it can be a bit of a chore both to unwind and wind the tape. Look at it as part of the onboard fitness program!

You can get fish tape at any hardware or home improvement store . . . or on Amazon if you just want it delivered to you:

  • Klein Tools Fish Tape – 4 different lengths; the end is slightly different than on ours (and I think this one is better)

On our boat, 25’ is sufficient and we’ve even used it to pull new reefing lines through the boom. If you’re running wires inside your mast, sometimes a longer fish tape is handy (sometimes you can do it with gravity; sometimes wires need some help if they have to pass through particular channels). NOTE: Fish tapes are made of mild steel (the ones made of nylon aren’t stiff enough to do the job) so it’s best to store it in a Ziploc with a dessicant pack to remove moisture from the air. If you have a microwave, Dry Tops work well as you can recharge them over and over.

Installing new equipment on a boat often requires new electrical wiring. Two tips for running that wiring in tight spaces.

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  • Tony
    Posted at 28 March 2016 Reply

    When you are running wire, you can attach a thin nylon line along with your wire and drag it through your wire run. The next time you need to run wire, just attach it to the nylon!

  • Bill Culbertson
    Posted at 28 March 2016 Reply

    Love the screw-connector/cable-tie idea. An alternative to traditional fish tape is a set of fiberglass rods. Centech makes a set using 33″ rods but on the boat I use their set of 12″ rods. Amazon has them here:
    -bill culbertson

  • Liz Aloha
    Posted at 28 March 2016 Reply

    Two more things to try when you’re having trouble running a wire:
    1) Take a long piece of thread and insert it at the beginning of the wiring run. Secure one end and leave the other end free. Put the hand nozzle of your ShopVac at the far end of the wiring run and suck the free end of the thread through. Use the thread as a leader to pull a stronger string through. Use the string to pull the wire through. Note that if the thread is light weight enough, the ShopVac will suck it through even if you can’t make a vacuum-seal at the far end of the run…you just need enough auction to get an air current flowing through there.

    2) Try spraying some sail-track lubricant or silicone lubricant on the exterior of things you’re having trouble shoving through: the fish itself, the wire, any leader strings, etc.

  • Pamela Douglas Webster
    Posted at 28 March 2016 Reply

    Easier, but still not a job I’m looking forward to. 🙂

    Mike Webster

    • Allan
      Posted at 20 December 2016 Reply

      running wires is always better than running pipes, IMHO

  • Raquel Hernandez
    Posted at 28 March 2016 Reply

    Brian Liddy

  • Will Klein
    Posted at 28 March 2016 Reply

    Armour All will make the plastic coating on the wire slippery and let it slide through more easily.

  • Paul
    Posted at 29 March 2016 Reply

    I’m not a big fan of metal fish tapes on the boat, corrosion the biggest issue as mentioned.
    I have had to run both new electrical wires and hoses (installed Air Conditioning) and found the best tool to feed the lines was a Fiberglass Multi part rod similar to the one used in Deflecto Dryer Duct Cleaning Kit, 12′ (amazon about $20) Easily stored and the kit I purchased had a end piece with a hole in it that I could secure a tie to the hose/wire.

    Totally agree with the idea of a Messenger line that can be used for future runs.


  • Stuart & Virginia
    Posted at 29 March 2016 Reply

    I use a length of plastic shroud cover (which are split all down one side). If the wire is small enough in diameter, open the split and insert a few inches of wire. That is usually tight enough to hold the wire but a tight wrap of electrical tape will also help. I pre-fish the shroud cover to find the best route for the wire. Even if the wire is larger than the diameter of the shroud cover, the split will still grip the electrical wire quite well…

  • Terry
    Posted at 31 March 2016 Reply

    Great idea.
    If you want to know our pro secret….get some 10mm by 3mm for 99% of the world or 3/4 inch by an 1/8th for the other 1% (joke)
    It’s plastic epansion joint holder for large wooden sections of board in houses….ask any electrician. It is solid side to side, yet flexible around bends.
    A small hole in one end allows you to push it through, connect cable and pull it back. I use it all the time. (Unless charging by the hour) 🙂
    like i said, this is a pro secret….so don’t tell anyone.

  • Michelle Rene
    Posted at 29 April 2017 Reply

    Great info and appreciate the comments of your followers. It’s always a hard job, these tips will make it less frustrating

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